factors influencing whakaraup - whaka-ora healthy...

Factors influencing the water quality of Lyttelton Harbour/ Whakaraupō Report No. R11/49 ISBN 978-1-927161-77-7 (printed) ISBN 978-1-927161-78-4 (web)

Lesley Bolton-Ritchie August 2011

Report R11/49 ISBN 978-1-927161-77-7 (printed) ISBN 978-1-927161-78-4 (web) PO Box 345 Christchurch 8140 Phone (03) 365 3828 Fax (03) 365 3194 75 Church Street PO Box 550 Timaru 7940 Phone (03) 687 7800 Fax (03) 687 7808 Website: www.ecan.govt.nz Customer Services Phone 0800 324 636

Factors influencing the water quality of Lyttelton Harbour/ Whakaraupō

Environment Canterbury Technical Report i

Easy to read summary The report is based on data collected by Environment Canterbury between 1992 and 2008 from sites in Lyttelton Harbour/Whakaraupō. The data are used to evaluate differences in water quality between sites and over time. They are also used to investigate the impact of wastewater discharges, stream inputs and sediment inputs on harbour water quality. The concentration of total phosphorus (TP), dissolved reactive phosphorus (DRP) and total suspended solids (TSS) and turbidity decreased with distance down the harbour. There were significant differences in water quality between sites in the harbour. The nutrient concentrations at the inner port entrance were variable and typically higher than at other sites in the harbour. There are numerous sources of nutrients to the inner port entrance including stormwater and stream flows, activities within the port and wastewater from the Lyttelton outfall. Total phosphorus and dissolved reactive phosphorus concentrations in harbour water have decreased over time. The total nitrogen concentration at the inner port entrance has increased over time. This increase results from an increase in the concentration of total organic nitrogen including particulate (living plankton and dead particulate matter) and dissolved organic nitrogen. In 2002-2003 nutrient concentrations were more similar between sites than they were in the other years. There was less rainfall in 2002-2003 than the other years. Around the harbour there are continually flowing streams as well as streams that dry up in summer. There were differences in nutrient and total suspended solids concentrations between streams and in each stream over time. Fresh water flowing from the streams influences the quality of the water in the harbour. Elevated nitrite-nitrate concentrations occur in harbour water after very heavy rainfall. Treated wastewater is discharged into the harbour via three outfalls. There was no indication that the wastewater results in elevated concentrations of indicator bacteria in sea water 10-20 m away from the Governors Bay outfall and 50 m away from the Diamond Harbour outfall. The wastewater may account for the occasional higher ammonia nitrogen concentration at sites 382-1530 m from an outfall. Soil erosion with rainfall and/or stirred up seabed sediments cause elevated harbour water TSS concentrations. The quantity of soil entering the harbour each year is not known. Soil input to the harbour could have an impact on marine life and is likely a significant ecological issue for the harbour. Around a third of the collected samples had a dissolved oxygen % saturation just below the guideline trigger value. It is uncertain whether the ecological health of the harbour will be affected by dissolved oxygen saturations less than the trigger value. Harbour water ammonia nitrogen concentrations were well below concentrations that could be toxic to marine life. The water in the areas classified as managed for contact recreation, meets the criteria for this classification. The water in the areas classified as managed for shellfish gathering applies to Rapaki Bay and the outer or eastern area of the harbour. The 2009 results from flesh testing of shellfish indicate this classification is being met. However, results from the routine monitoring of overlying water faecal coliform concentrations in Rapaki Bay indicate the classification is not typically met. The following recommendations have been made.

1. Undertake monthly water quality sampling at sites throughout the harbour, for a year every five years.

2. Undertake investigations to determine the sources of nutrients to Living Springs Creek and Rapaki Stream and the sources of faecal contamination to Living Springs Creek, Teddington Stream, Te Wharau Stream and Purau Stream.

3. Stricter on-land erosion control measures are required to reduce the quantities of soil entering harbour water.


ii Environment Canterbury Technical Report


Environment Canterbury Technical Report iii

Executive summary Water quality data collected by Environment Canterbury from sites in Lyttelton Harbour/Whakaraupō over four time periods between 1992 and 2008 were used to evaluate the state of nutrient, soil/sediment and micro-organism concentrations within harbour water. The data were also used to provide an indication of the impact of wastewater discharges, stream inputs and sediment inputs on the water quality of Lyttelton Harbour/Whakaraupō. There were significant differences in ammonia nitrogen (NH3N), nitrate-nitrite nitrogen (NNN), total nitrogen (TN), dissolved reactive phosphorus (DRP), total phosphorus (TP), total suspended solids (TSS), turbidity and chlorophyll-a concentrations between sites. Typically TP, DRP, turbidity and TSS concentrations decreased with distance down the harbour but NNN, NH3N and TN concentrations did not. At one or more sites TN, DRP and TP concentrations but not NH3N and NNN concentrations were significantly different over time. For DRP and TP there was a significant decrease, but for TN there was a significant increase, in concentration over time. An increase in the mean TN concentration occurred at the inner port entrance with this increase attributed to an increase in the total organic nitrogen (TON) concentration. This TON could be from a combination of particulate (living plankton and dead particulate matter) and dissolved (simple (amino acids) to complex nitrogen compounds), organic nitrogen. The 1993-1994 and 2002-2003 nutrient concentrations were similar while the 2007-2008 nutrient concentrations were more similar to those from 1992-1993 than from the other two time periods. The 2002-2003 nutrient concentrations were more similar between sites than they were in the other years. There was less rainfall in 2002-2003 than the other years which may account for this result.

There are continually flowing and ephemeral waterways around the harbour. There were differences in nutrient and total suspended solids concentrations between waterways and over time. The influence of rainfall quantity and hence stream flows on NNN, TN and DRP concentrations at five harbour sites was investigated. For TN and DRP there was no increase in harbour water concentrations as rainfall volume increased. For NNN the highest concentrations appear to result from very heavy rainfall, i.e. 50 mm prior to sampling. The variation in salinity between sites in the harbour indicates that inputs from the waterways have a considerable influence on harbour water. Treated wastewater is discharged into the harbour via three outfalls, with the maximum consented wastewater volume being 15,196 m3/day. High faecal indicator organism concentrations in treated wastewater did not result in high concentrations in sea water 10-20 m away from the Governors Bay outfall and 50 m away from the Diamond Harbour outfall. There were no data available for the Lyttelton outfall. NH3N concentrations were used to assess the influence of wastewater on harbour water. NH3N concentrations at sites 382 - 2300 m away from an outfall were not notably higher than those at other harbour sites. However, wastewater may account for the occasional higher NH3N concentration at sites 382 – 1530 m from an outfall. At the inner port entrance there were peaks in nutrient concentrations at times and significantly higher NNN, NH3N, DRP and TP concentrations at this site than at two or more of the other harbour sites. These results suggest nearby sources of nutrients e.g. stormwater and stream flows, activities within the port and wastewater from the Lyttelton outfall. Soil erosion and/or re-suspension of fine seabed sediments as a result of shallow water in combination with wind generally account for elevated TSS concentrations at sites. It is difficult to separate out the effect of soil erosion due to rainfall, and re-suspension of seabed sediments because rainfall is typically accompanied by moderate to high winds. There are no data on the actual quantity of soil entering the harbour each year, but there are concerns it is increasing. Soil input to the harbour has the potential to impact the ecological health of marine life and is likely a significant ecological issue for the harbour.


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Thirty percent of samples had a dissolved oxygen saturation of less than the guideline trigger value of 90% with the lowest value being 85% saturation. Saturations of less than 90% could be a function of the impact of water temperature rather than oxygen depletion by micro-organisms and animals. It is uncertain whether there is potential for the ecological health of the harbour to be affected by the lower than trigger value dissolved oxygen saturations. All harbour water NH3N concentrations were below the ANZECC (2000) trigger value providing protection for 99% of species. Wastewater discharged into the harbour needs to be diluted up to 54 times to achieve NH3N concentrations providing protection for 99% of marine species. The water quality class of water managed for contact recreation, which applies to the western part of Lyttelton Harbour/Whakaraupō is being met. The water quality class of water managed for shellfish gathering applies to Rapaki Bay and the outer or eastern part of Lyttelton Harbour/Whakaraupō. The results from flesh testing of shellfish in 2009 indicate this classification is being met. Results from the routine monitoring of overlying water faecal coliform concentrations in Rapaki Bay indicate the classification is not typically met. Faecal coliform concentrations in Rapaki Bay are influenced by rainfall and wind with land runoff, stormwater and seabed sediments the likely sources. The following recommendations have been made.

1. Undertake routine water quality sampling at sites throughout the harbour, at, at least a monthly frequency for a year every five years.

2. For any future assessment of the influence of wastewater effluent and freshwater flows on harbour water quality, the waterways (water quality and flows), wastewater quality and harbour water quality sampling should either be on the same day, or the waterways and wastewater should be sampled the day prior to harbour sampling.

3. Undertake investigations to determine the sources of nutrients to Living Springs Creek and Rapaki Stream and the sources of faecal contamination to Living Springs Creek, Teddington Stream, Te Wharau Stream and Purau Stream.

4. While data could be collected to determine the quantities of soil/sediment that are entering the harbour via the streams, stricter on-land erosion control measures are required to reduce these quantities.


Environment Canterbury Technical Report v

Table of contents

Easy to read summary ............................................................................................... i

Executive summary .................................................................................................. iii

1 Introduction ..................................................................................................... 1

1.1 Background ..................................................................................................................... 1

1.2 Objectives ....................................................................................................................... 4

2 Water quality through the harbour and over time ........................................ 6

2.1 Introduction and background .......................................................................................... 6 2.2 Data collection and analysis ........................................................................................... 6

2.2.1 Sampling sites and sampling frequency ............................................................ 6 2.2.2 Sample collection and laboratory analyses ....................................................... 9 2.2.3 Data analyses .................................................................................................... 9

2.3 Parameter concentrations through the harbour ............................................................10

2.4 Parameter concentrations between sites .....................................................................18 2.5 Seasonality ...................................................................................................................20

2.6 Nutrient concentrations at each site over time .............................................................25

2.7 Parameter concentrations between years ....................................................................27

2.8 Factors affecting harbour water quality ........................................................................27 2.8.1 Rainfall .............................................................................................................29 2.8.2 Wind .................................................................................................................29

2.9 Discussion .....................................................................................................................30

3 Nutrient inputs to harbour water ................................................................. 33

3.1 Streams/creeks flowing to the harbour .........................................................................33 3.1.1 Nutrient concentrations in harbour streams .....................................................34 3.1.2 Impacts of stream/creek inputs on harbour water salinity................................36 3.1.3 Impact of stream inputs on harbour water nutrient concentrations ..................36

3.2 Wastewater discharges ................................................................................................39 3.2.1 Details of the discharge from each wastewater outfall ....................................40 3.2.2 Effluent mixing and distribution ........................................................................44 3.2.3 Influence of wastewater discharges on harbour water quality .........................45

3.3 Discussion .....................................................................................................................52

4 Total suspended solids concentrations in harbour water ......................... 54

4.1 Water depth and TSS concentrations ...........................................................................54 4.1.1 Water depths at the sampling sites ..................................................................55 4.1.2 Total suspended solids concentrations ............................................................55 4.1.3 Total suspended solids and water depth .........................................................55 4.1.4 Seabed sediments at sites shallower than 5 metres .......................................56

4.2 Factors influencing total suspended solids concentrations ..........................................57 4.3 Increase in suspended solids concentrations ...............................................................59


vi Environment Canterbury Technical Report

4.4 Total suspended solids concentrations following heavy rainfall ...................................59

4.5 Other influences on TSS concentrations ......................................................................60

4.6 Discussion .....................................................................................................................60

5 Microbiological water quality ....................................................................... 62

5.1 Introduction ...................................................................................................................62

5.2 Sources of micro-organisms to harbour water ..............................................................62 5.2.1 Wastewater discharges ....................................................................................62 5.2.2 Waterways .......................................................................................................63 5.2.3 Stormwater .......................................................................................................63 5.2.4 Birds .................................................................................................................64

5.3 Concentrations of faecal indicator organisms in harbour water ...................................65 5.3.1 In proximity to wastewater outfalls ...................................................................65 5.3.2 Swimming beaches ..........................................................................................65 5.3.3 Water overlying shellfish ..................................................................................66

5.4 Micro-organisms in shellfish flesh .................................................................................67

5.5 Discussion .....................................................................................................................69

6 Overall assessment of harbour water quality ............................................. 70

6.1 Water quality for ecological health ................................................................................70 6.1.1 Oxygen concentrations ....................................................................................70 6.1.2 Nutrient concentrations ....................................................................................70 6.1.3 Chlorophyll-a concentrations ...........................................................................72 6.1.4 Total suspended solids concentrations ............................................................73

6.2 Water quality for contact recreation and shellfish gathering .........................................74 6.2.1 Water managed for the maintenance of aquatic ecosystems (Coastal AE) ....74 6.2.2 Water managed for contact recreation (Coastal CR).......................................75 6.2.3 Water managed for shellfish gathering (Coastal SG) ......................................75

7 Future investigations and monitoring ......................................................... 75

8 Acknowledgements ...................................................................................... 76

9 References ..................................................................................................... 77

Appendix 1: Sampling sites .................................................................................... 79

Appendix 2: Description of parameters ................................................................. 80

Appendix 3: Nutrient analyses and detection limits ............................................. 82

Appendix 4 Summary data for parameters............................................................ 83

Appendix 5: Between site comparison of nutrient concentrations in surface water .................................................................................................... 87

Appendix 6: Wind direction and speed in each year of sampling ....................... 90

Appendix 7: Parameter concentrations in six harbour streams/creeks ............. 92

Appendix 8: Rainfall at Coopers Knob .................................................................. 95


Environment Canterbury Technical Report vii

Appendix 9: Details of harbour sampling sites and adjacent streams/creeks ... 96

Appendix 10: Volume of treated wastewater (m3/day) discharged from each of the outfalls in the five days prior to water quality sampling ...... 97

Appendix 11: Total suspended solids ................................................................... 98

Appendix 12: Faecal coliform and enterococci concentrations in the discharged wastewater and the receiving environment ................. 99

Appendix 13: Suitability for recreation grades ................................................... 101

Appendix 14: Relationship between DO %saturation and water temperature in harbour water ............................................................................... 104

List of Figures Figure 1-1: Lyttelton Harbour/Whakaraupō, its catchments, roading and urbanised areas ................ 2 Figure 1-2: Looking down the harbour from the hilltop above Governors Bay .................................... 3 Figure 2-1: Location of harbour sampling sites.................................................................................... 7 Figure 2-2: View of the inner port; the inner port entrance sampling site is between the

breakwaters ....................................................................................................................... 8 Figure 2-3: View of Lyttelton and the inner port with the northern head in the distance ..................... 8 Figure 2-4: Ammonia nitrogen concentrations (mg/L) at sites in Lyttelton Harbour/Whakaraupō in

four time periods ..............................................................................................................11 Figure 2-5: Nitrite-nitrate concentrations (mg/L) at sites in Lyttelton Harbour/Whakaraupō in four

time periods .....................................................................................................................12 Figure 2-6: Total nitrogen concentrations (mg/L) at sites in Lyttelton Harbour/Whakaraupō in four

time periods .....................................................................................................................13 Figure 2-7: Dissolved reactive phosphorus concentrations (mg/L) at sites in Lyttelton

Harbour/Whakaraupō in four time periods ......................................................................14 Figure 2-8: Total phosphorus concentrations (mg/L) at sites in Lyttelton Harbour/Whakaraupō in

four time periods ..............................................................................................................15 Figure 2-9: Chlorophyll-a concentrations (µg/L) at sites in Lyttelton Harbour/Whakaraupō in two

time periods .....................................................................................................................16 Figure 2-10: Total suspended solids concentrations (mg/L) at sites in Lyttelton

Harbour/Whakaraupō in 2007- 2008 (T4) .......................................................................16 Figure 2-11: Turbidity (NTU) at sites in Lyttelton Harbour/Whakaraupō in two time periods ..............17 Figure 2-12: Salinity (ppt) at sites in Lyttelton Harbour/Whakaraupō in 2007- 2008 (T4) ...................17 Figure 2-13: Dissolved oxygen (% saturation) at sites in Lyttelton Harbour/Whakaraupō in 2007-

2008 (T4) .........................................................................................................................18 Figure 2-14: Seasonality of nitrite-nitrate nitrogen concentrations ......................................................21 Figure 2-15: Seasonality of dissolved reactive phosphorus concentrations ........................................22 Figure 2-16: Seasonality of total phosphorus concentrations ..............................................................23 Figure 2-17: Seasonal differences in chlorophyll-a concentrations .....................................................24 Figure 2-18: Differences in TN, DRP and TP concentrations (mg/L) over time ..................................26


viii Environment Canterbury Technical Report

Figure 2-19: MDS ordination of mean nutrient concentrations for each season, in each year at each site ..........................................................................................................................28

Figure 2-20: MDS ordination of mean nutrient concentrations for each season, in each year at each site ..........................................................................................................................28

Figure 3-1: Harbour streams with stream and adjacent harbour sampling sites marked ..................33 Figure 3-2: Te Wharau Stream and its catchment, Charteris Bay .....................................................34 Figure 3-3: Salinity (ppt) at harbour sites, 2007-2008 .......................................................................36 Figure 3-4: The influence of pre-sampling rainfall quantity on NNN, TN and DRP concentrations

at five harbour sites .........................................................................................................38 Figure 3-5: Location of wastewater outfalls (green circles) and the closest water quality sampling

sites ................................................................................................................................39 Figure 3-6: Daily wastewater discharge volumes, Lyttelton outfall, January 2007-June 2008 ..........40 Figure 3-7: Daily wastewater discharge volumes, Governors Bay outfall, January 2007-June

2008 .................................................................................................................................41 Figure 3-8: Nutrient concentrations (mg/L) in effluent discharged from the Governors Bay outfall,

January 2007- June 2008 ................................................................................................41 Figure 3-9: Daily wastewater discharge volumes, Diamond Harbour outfall, January 2007-June

2008 .................................................................................................................................43 Figure 3-10: Nutrient concentrations (mg/L) in effluent discharged from the Diamond Harbour

outfall, January 2007- June 2008 ....................................................................................43 Figure 3-11: Water circulation in Lyttelton Harbour/Whakaraupō .......................................................45 Figure 3-12: View of Church Bay and the Diamond Harbour wastewater treatment plant ..................46 Figure 3-13: Box and whisker plots of the ammonia nitrogen concentrations at each site in .............47 Figure 3-14: The influence of state of the tide and wind direction at the time of sampling on

ammonia nitrogen concentrations (mg/L) at the Governors Bay site ..............................49 Figure 3-15: The influence of state of the tide and wind direction at the time of sampling on

ammonia nitrogen concentrations (mg/L) at the Quail-Rapaki site .................................49 Figure 3-16: The influence of state of the tide and wind direction at the time of sampling on

ammonia nitrogen concentrations (mg/L) at the Church Bay site ...................................50 Figure 3-17: The influence of state of the tide and wind direction at the time of sampling on

ammonia nitrogen concentrations (mg/L) at the inner port entrance site .......................51 Figure 3-18: The influence of state of the tide and wind direction at the time of sampling on

ammonia nitrogen concentrations (mg/L) at the Ripapa-Battery site ..............................51 Figure 4-1: Aerial view of the upper harbour, January 2009. Head of the Bay in the foreground

and Governors Bay and the northern shoreline are in the background. Pegasus Bay in the distance at the top of the picture ...........................................................................54

Figure 4-2: Surface water total suspended solids concentrations (mg/L) in relation to water depth .56 Figure 4-3: Total suspended solids concentrations (mg/L) at harbour sites in 2007-2008 ...............57 Figure 5-1: Percentage of samples containing less than 140 enterococci/100 mL ...........................66 Figure 5-2: Location of shellfish collection sites ................................................................................68 Figure 6-1: Dissolved oxygen saturation (%) at harbour sites in 2007- 2008 ....................................71 Figure 6-2: N:P ratio in all samples collected from each of the harbour sites ...................................72 Figure 6-3: Lyttelton Harbour/Whakaraupō water quality classes .....................................................74


Environment Canterbury Technical Report ix

List of Tables

Table 1.1: Harbour water contaminants and their potential sources .................................................. 4 Table 2.1: Water quality parameters .................................................................................................. 9 Table 2.2: Total rainfall (mm) at Coopers Knob over each year of sampling ...................................29 Table 3.1: Summary of nutrient concentrations in six harbour streams, September 2007 –

December 2008 ...............................................................................................................35 Table 3.2: Mass loads of ammonia nitrogen, total nitrogen and dissolved reactive phosphorus

discharged into the harbour from the Governors Bay outfall ..........................................42 Table 3.3: Mass loads of ammonia nitrogen, total nitrogen and dissolved reactive phosphorus

discharged into the harbour from the Diamond Harbour outfall ......................................44 Table 3.4: Summary of ammonia nitrogen concentrations at each site in 2002-2003 and 2007-

2008 .................................................................................................................................46 Table 4.1: Summary of water depth (m) at the time of sampling .....................................................55 Table 4.2: Percentage composition of the seabed sediment ...........................................................56 Table 4.3: Summary of possible explanations for the total suspended solids concentrations of >

20 mg/L at five sites ........................................................................................................58 Table 4.4: Relative increases in total suspended solids concentrations at the shallower sites .......59 Table 5.1: Faecal indicator organism concentrations in each wastewater discharge ......................63 Table 5.2: E. coli concentrations (MPN/100mL) in six harbour streams/creeks ..............................64 Table 5.3: Faecal coliform concentrations (cfu/100mL) in Rapaki Bay water over the last five

summers ..........................................................................................................................67 Table 5.4: Faecal indicator organism concentrations in blue mussel and pipi flesh from harbour

sites .................................................................................................................................68 Table 6.1: Chlorophyll-a concentrations > 5 μg/L at harbour sites, 2007-2008 ................................72


x Environment Canterbury Technical Report


Environment Canterbury Technical Report 1

1 Introduction

1.1 Background Lyttelton Harbour/Whakaraupō was formed through the eruption of the now dormant Miocene volcano Mt Lyttelton approximately 2 million years before present. The harbour basin is 1.35 - 5.5 km wide and at high tide approximately 15 km long, covering an area of about 44 km2 (Spigel, 1993). The hillsides around the harbour basin are generally steep and cover an area of about 9968 ha. The hillside soils are primarily basaltic mantle substrates beneath greywacke loess (≤ 20 m) and loess colluviums (volcanic detritus) (Hart, 2004). Due to the high proportion of loess and steep slopes of the harbour margin, the soils are highly susceptible to erosion, particularly where there is no vegetation cover (Hart, 2004). The tangata whenua of the harbour area are Te Hapū o Ngāti Wheke (Rāpaki rūnunga) of Ngāi Tahu. They have a history of settlement around the harbour with Rāpaki on the northern shore of the harbour (Figure 1-1), the present day hub for Rāpaki rūnunga. This harbour provides for their cultural and spiritual well being and as tangata whenua they take responsibility as kaitiaki (guardians) to protect Lyttelton Harbour/Whakaraupō. Of particular importance to their cultural and traditional relationship with the harbour is their ability to harvest kaimoana (shellfish and fish) from the harbour for customary manaakitanga (hospitality toward guests); this maintains the mana of the hapū. The township of Lyttelton is the largest urbanised area of the harbour (population 3075 in 2006; Environment Canterbury, 2008). Many of the bays accessible by road now have urbanised areas (Figure 1-1). These include Corsair Bay, Cass Bay, Rapaki, Governors Bay, Church Bay, Diamond Harbour and Purau. In 2006 there was a population of 1089 in Diamond Harbour and 870 in Governors Bay. The scenic harbour environs and microclimates of the bays coupled with their accessibility from Christchurch City make the bays a popular location to live. Hence subdivision developments are now occurring on steeper slopes within the bays and on headlands. In early 2007 ten subdivision developments were underway (Environment Canterbury, 2008). With increasing urbanisation comes increasing volumes of sewage (wastewater), stormwater and more roading. Reticulated sewerage systems are in place in Governors Bay, Diamond Harbour/Church Bay and Lyttelton, with the Lyttelton system servicing the communities of Lyttelton, Corsair Bay, Cass Bay and Rapaki. From the reticulated systems the sewage is discharged into the harbour through outfalls off Diamond Harbour (Pauaohinekotau Head), Governors Bay and Lyttelton (Sticking Point). Households in Ohinetahi, Allandale, Teddington, Head of the Bay, Charteris Bay and Purau rely on septic tanks or more modern on-site systems for sewage treatment. The stormwater, which is untreated, typically flows into waterways which then discharge into the harbour. Stormwater is a source of rubbish, sediments, pathogens, organic matter, chemical contaminants such as heavy metals and organic compounds, and possibly nitrogen and phosphorus compounds to harbour water (Morrisey, 1997; Vincent and Thomas, 1997). The roads are a drainage pathway for soil and stormwater runoff from the hillsides and the metals and other contaminants from vehicles that travel along it. From the road surfaces the contaminants end up in roadside drains and culverts and from there are transported down slope into waterways and eventually the sea. In addition many of the roads are cut into the hillside with the road cuttings being exposed bare soil. Soil from these exposed cuttings is eroded by rainfall. As a consequence of historic deforestation by Māori and European settlers, the steep slopes of the harbour margin are now typically covered with pasture grasses (Figure 1-2). However, there are pockets of native and exotic forest and scrub, as well as bare vertical rock faces. Historic and active erosion scars are a feature of the deforested hillsides with soil runoff into the harbour a significant issue. Eroded hillside has in-filled the harbour basin with sediment up to a maximum depth of 47 m (Hart, 2004). Through thousands of years of soil erosion, extensive tidal flats have accreted at Governors Bay, Head of the Bay, and Charteris Bay. These flats cover a combined area of 11 km2 at mean low water spring (MLWS) tide (Hart, 2004). There is evidence of a number of periodic soil erosion events and accretion of sediment within the harbour over the period 1849 to the present day (Curtis, 1985, Goff, 2005).


2 Environment Canterbury Technical Report

Figure 1-1: Lyttelton Harbour/Whakaraupō, its catchments, roading and urbanised areas



Figure 1-2: Looking down the harbour from the hilltop above Governors Bay

Continuous earthworks for subdivision development, exposed roadside cuttings and the active erosion scars on the hillsides mean that soil erosion and hence sediment accretion in the harbour basin will always occur. However, human influences have modified the natural rate of erosion around the harbour. The Port of Lyttelton, located about midway down the northern side of the harbour (Figure 1-1), is a busy commercial port that has serviced Canterbury for over 150 years. The present day port facilities include: container, oil tanker and roll-on roll-off facilities; coal storage and loading facilities; a dry dock; a cattle wharf; general shipping, fishing boat and cement shipping berths; and yacht moorings. From time to time there are spillages of fuel and cargo, e.g. fertiliser, into the harbour affecting the water quality. The quality of the water within the inner port is also influenced by stormwater from Lyttelton township and the port facilities. Many of the changes and activities described above have the potential to add contaminants to Lyttelton Harbour/Whakaraupō water (Table 1.1). The potential sources and hence type and quantity of contaminants entering harbour water, differ with location around the harbour. Given that these contaminants affect the quality of harbour water, there is potential for the water quality to differ between locations in the harbour and to change over time. The input of any of these contaminants to harbour water is of concern. However, the local community is particularly concerned about the following specific contaminant sources and their impact on harbour water quality:

• the impact of wastewater discharges on harbour water nutrient concentrations and potential for algal blooms, and microbial water quality for swimming and shellfish gathering.

• the impact of stream inputs on harbour water nutrient concentrations and potential for algal blooms, and microbial water quality for swimming and shellfish gathering.

• the input of soil/sediment on harbour water suspended sediment concentrations. Environment Canterbury has collected water quality data from sites within Lyttelton Harbour/Whakaraupō since 1992. The focus has been on nutrient concentrations but total suspended solids concentrations (an indication of soil/sediment concentration) were measured over 2007-2008. Micro-organism concentrations have not been measured at sites throughout the harbour, but for some years there has been routine summer sampling of faecal indicator micro-organism concentrations at popular swimming sites. Environment Canterbury has not measured dissolved metal and hydrocarbon concentrations in sea water. Metals adsorb to sediment particles and settle to the seabed. To assess metal contamination it is advisable to measure concentrations in seabed sediments rather than in sea water. Hydrocarbons are expensive to measure, and the less volatile components settle to the sea bed. That is, like metals it is advisable to measure concentrations in seabed sediments rather than in sea water.



Table 1.1: Harbour water contaminants and their potential sources

These collected data allow for an evaluation of the present nutrient, soil/sediment and micro-organism concentrations at sites within the harbour. They also allow for an assessment of the impact of wastewater discharges, stream inputs and sediment inputs on the water quality of Lyttelton Harbour/Whakaraupō. However, it is important to note that sampling sites and sampling design were established to determine if there were differences in water quality between sites and over time for the purposes of monitoring the effectiveness of the Regional Council’s policies and plans. The assessment of the impact of wastewater discharges, stream inputs and sediment inputs is based on the routinely collected data. No specific data, such as at sites positioned at set distances away from a wastewater discharge, or sampling during different rainfall and wind conditions, were collected to assess these specific inputs. This means that the assessment of impacts based on these data can at best provide an indication of impacts rather than definitive answers.

1.2 Objectives The objectives of this report were to:

1. Use Environment Canterbury water quality data, collected over time from sites throughout

The harbour, to assess harbour water quality. This includes the evaluation of: • water quality parameter concentrations down the harbour. • differences in water quality parameter concentrations between sites. • water quality parameter concentrations at each site over time. • differences in water quality parameter concentrations between sites over time.

This assessment will make it possible to determine whether the water quality of Lyttelton Harbour/Whakaraupō has declined over time.

Contaminant Potential sourcesSewage effluent (wastewater discharges)StormwaterStreamsRunoff from landHistoric and active erosion scarsSubdivision developmentRoad cuttingsStormwaterStreamsRunoff from landSewage effluent (wastewater discharges)StormwaterStreamsRunoff from landBirdsStormwaterRoadsStormwaterRoads

Hydrocarbons

Micro-organisms

Nutrients

Soil/sediment

Metals



2. Use water quality data to investigate the impacts of: • wastewater discharges • freshwater flows • soil/sediment runoff from the land

on Lyttelton Harbour/Whakaraupō water quality (nutrients, soil/sediment and micro-organism concentrations).

3. Use Environment Canterbury water quality data to assess whether:

• the water quality in the harbour is a cause for ecological concern • the standards for Regional Coastal Environment Plan water quality classes

within the harbour are being met. To achieve these objectives this report is divided into the following chapters:

1. Water quality through the harbour and over time 2. Nutrient inputs to harbour water 3. Total suspended solids concentrations in harbour water 4. Microbial water quality 5. Assessment of harbour water quality.

By using this reporting format specific concerns on factors influencing Lyttelton Harbour/Whakaraupō water quality are investigated and at the same time nutrients, soil/sediment and micro-organism concentrations and inputs to the harbour are investigated.



2 Water quality through the harbour and over time

2.1 Introduction and background The objective of this chapter is to describe the water quality in Lyttelton Harbour/Whakaraupō. Water quality data collected over time have been analysed to evaluate:

1. the concentrations of water quality parameters down the harbour, i.e. from the upper to outer harbour;

2. the differences in water quality parameter concentrations between sites; 3. the concentrations of water quality parameters at each site over time; 4. the differences in water quality parameter concentrations between sites over time.

In addition seasonality of water quality parameter concentrations and differences in rainfall and wind between the years sampled are examined as they are potential causes of differences in parameter concentrations over time. These analyses will make it possible to determine whether the water quality has declined over time. This evaluation of the water quality through the harbour and over time incorporates the most recently collected data, i.e. 2007-2008, with that collected since 1992. The data collected prior to 2007-2008 were analysed and reported in 2004 (Bolton-Ritchie, 2004). Some of the results from the 2004 report are incorporated into the evaluation of water quality parameters at each site to determine if there are obvious and consistent patterns. The historic data have also been used to assess changes in parameter concentrations over time. In 2004 it was found that:

1. nitrite-nitrate nitrogen concentrations were generally higher at the inner port entrance than at other sites.

2. dissolved reactive phosphorus and total phosphorus concentrations were generally higher at upper harbour sites (Charteris Bay, Governors Bay and Corsair Bay) and the inner port entrance than at outer harbour sites (harbour entrance, Purau Bay and Ripapa).

3. there was no obvious pattern to differences in ammonia nitrogen and total nitrogen concentrations between sites.

4. there was no overall trend of a decrease or increase in nutrient concentrations in Lyttelton Harbour/Whakaraupō over time.

2.2 Data collection and analysis

2.2.1 Sampling sites and sampling frequency Water quality sampling was undertaken at sites in Lyttelton Harbour/Whakaraupō (Figure 2-1) (Appendix I). When routine water quality sampling of Lyttelton Harbour/Whakaraupō was initiated (1988) by the North Canterbury Catchment Board and Regional Water Board, the sites selected were the same as those sampled in 1976 (Millhouse, 1977). For continuity six of the sites initially sampled have remained in the sampling programme over time. These six sites are Charteris Bay, Governors Bay, Corsair Bay, inner port entrance, Purau Bay and harbour entrance. However, prior to the start of the 2007-2008 sampling, some site changes were made. Three new sites, Quail-Rapaki, Church Bay and Battery-Ripapa were added and the Ripapa site was dropped. Sampling in Church Bay began as a result of concerns raised by local residents on the impact of discharged Diamond Harbour sewage effluent on the water quality in this bay. The location of the outer harbour site was changed from Ripapa to Battery-Ripapa in order to sample mid harbour water rather than water closer to one shore than another. The Quail-Rapaki site was added in order to obtain more water quality data from the upper harbour.



Figure 2-1: Location of harbour sampling sites Black dot – sampled July 1992 - June 2008 Blue dot – sampled July 1992 - June 2003 Red dot – sampled July 2007 - June 2008

This report includes data collected approximately monthly over a year-long period during:

• 1992-1993 (on 11 occasions between 16 July 1992 and 17 June 1993) • 1993-1994 (on 12 occasions between 12 July 1993 and 30 May 1994) • 2002-2003 (on 11 occasions between 29 July 2002 and 16 June 2003) • 2007-2008 (on 12 occasions between 9 July 2007 and 3 June 2008)

The sampling in the 90s was in line with the sampling programme initiated in 1988. However, in 2000-2001 the sampling programme, and particularly the frequency of sampling, was changed. At that time Environment Canterbury initiated a coastal water quality monitoring programme to support the then proposed Regional Coastal Environment Plan for the Canterbury region (RCEP). For the purposes of this monitoring programme the Canterbury coast was divided into five areas; Lyttelton Harbour/Whakaraupō is one of these areas. The monitoring programme consists of routine water sampling at sites in each area over a year, every five years. To this end sites in Lyttelton Harbour/Whakaraupō sites were sampled in 2002-2003 and again in 2007-2008.



Figure 2-2: View of the inner port; the inner port entrance sampling site is between the breakwaters

Photo supplied by Robyn Croucher, Environment Canterbury

Figure 2-3: View of Lyttelton and the inner port with the northern head in the distance



2.2.2 Sample collection and laboratory analyses The samples were collected by Environment Canterbury staff. All sampling was carried out from a boat. At each site surface water (0 – 0.5 m water depth) was collected. All water was collected in specially prepared bottles provided by the laboratory undertaking the analyses, and kept cooled in chilly bins until delivery to the laboratory. In the field the water temperature, salinity and dissolved oxygen were measured using field meters and general weather observations were recorded at the time of sampling. In the laboratory water samples were analysed for a range of parameters (Table 2.1). A detailed description of these parameters is given in Appendix 2. Laboratory analyses of the 1992-1994 harbour samples were carried out by the Cawthron Institute. All other analyses were carried out by Environment Canterbury. The details of analytical methods for the N and P-based parameters are given in Appendix 3.

Table 2.1: Water quality parameters

2.2.3 Data analyses The data were analysed to investigate whether there were significant differences in parameter concentrations between sites and over time. The details of all analyses are described below. Parameter concentrations between sites To determine if there was a significant difference in the concentration of each parameter between sites in each sampling period the non-parametric Wilcoxon two-tailed signed rank test was used. Seasonality of parameter concentrations To determine if there is seasonality of ammonia nitrogen (NH3N), nitrite-nitrate nitrogen (NNN), total nitrogen (TN), dissolved reactive phosphorus (DRP), total phosphorus (TP) and chlorophyll-a concentrations, data collected over time from each site were grouped by season. Winter – June, July, August; Spring – September, October, November; Summer – December, January, February; Autumn – March, April, May. Sites sampled in more than one sampling period, i.e. Governors Bay, Charteris Bay, Corsair Bay, the inner port entrance, Purau Bay and the harbour entrance, were used for this analysis. To determine if there was a significant difference in the concentration of each parameter between seasons the non-parametric Kruskal-Wallis ANOVA (Analysis of Variance) (Statistica v7) was used. Differences in nutrient concentrations at each site over time To determine if there was a significant difference in the concentration of each parameter over time the nonparametric Kruskal-Wallis ANOVA (Analysis of Variance) (Statistica v7) was used. Because there are large temporal gaps in the data, a between sampling years comparison could be skewed by

Parameter UnitAmmonia nitrogen (NH3N) mg/L

Nitrite-nitrate nitrogen (NNN) mg/L

Total nitrogen (TN) mg/L

Dissolved reactive phosphorus (DRP) mg/L

Total phosphorus (TP) mg/L

Turbidity NTU

Total suspended solids (TSS) mg/L

Dissolved oxygen saturation (DO sat.) %

Salinity ppt

Water Temperature °C



differences in weather and other climatic influences. Hence a big picture evaluation was undertaken with the data grouped by decade - the 1990s (1992-1994) and 2000s (2002-2003 and 2007-2008). Only sites sampled over all four years were used for this analysis. These sites were Governors Bay, Charteris Bay, Corsair Bay, the inner port entrance, Purau Bay and the harbour entrance. The time definition also restricted the parameters that could be analysed to NH3N, NNN, TN, DRP and TP.

Nutrient concentrations between years Nutrient concentrations were used to investigate similarities and differences in water quality at and between sites over time. The data were used to produce MDS ordinations. On an MDS ordination sites are plotted in a spatial array, and the closer together the sites the more similar they are with regard to the parameters used to generate the ordination. MDS ordinations were used to investigate:

Similarities and differences in nutrient concentrations between years Similarities and differences in nutrient concentrations between seasons within years

Nutrient data from the six sites sampled in each of the four time periods were used. The mean concentration of each nutrient for each season in each time period was for each site (six sites, four seasons and four years of sampling) was used. The data were log10(x+1) transformed then the Euclidean distance measure was applied to produce a similarity matrix. From this similarity matrix an MDS ordination was generated. Primer (v 6), Statistica (v 7) and Microsoft Excel were used for data analyses and production of graphs.

2.3 Parameter concentrations through the harbour The summary data for the parameters are presented in Appendix 4. For all parameters except water temperature, all data were used to construct box and whisker graphs for each time period at each site (Figures 2-4 – 2-13). In these graphs the sites, positioned along the x-axis, grade from upper harbour sites on the left to outer harbour sites on the right. A line of fit of the medians is shown on each plot. This line of fit provides an indication only in the change in parameter concentration with location from upper to outer harbour. The box and whisker plots show:

1. NH3N and NNN concentrations varied between sites. There was no pattern in NH3N and NNN concentrations down the harbour, i.e. from the upper harbour to the harbour entrance.

2. TN concentrations were lower at the harbour entrance than at other sites. 3. DRP, TP, turbidity and TSS concentrations typically decreased with increasing distance down

the harbour from the upper harbour to the harbour entrance. 4. chlorophyll-a concentrations varied between sites. However, concentrations were typically

lower at the upper harbour sites than at sites in the mid to outer harbour. 5. salinity was higher in the outer harbour and at the harbour entrance than at the upper most

harbour sites. 6. DO % saturation varied between sites. DO % saturation was higher at the harbour entrance

that at sites in the harbour.

Factors influencing the water quality of Lyttelton H

arbour/ Whakaraupō

Environment C

anterbury Technical Report

11

Gove

Gove

Gove

Gove

Charte

Charte

Charte

Charte

Quail-R

Corsair B

Corsair B

Corsair B

Corsair B

Church B

In

In

In

In

Purau Bay

Purau Bay

Purau Bay

Purau Bay

Ripapa T1

Ripapa T2

Ripapa T3 R

ipap

Ha

Ha

Ha

Ha

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

NH

3N (mg/L)

Figure 2-4: Ammonia nitrogen concentrations (mg/L) at sites in Lyttelton Harbour/Whakaraupō in four time periods box = interquartile range, whisker ends = % and 95%iles, = outlier values, = extreme values, dashed line = line of fit of medians

T1 = 1992-1993

T2 = 1993-1994

T3 = 2002-2003

T4 = 2007-2008

12 Environm

ent Canterbury Technical R

eport


arbour/ Whakaraupō

Gove

Gove

Gove

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Charte

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Charte

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Quail-R

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Church B

In

In

In

In

Purau Bay

Purau Bay

Purau Bay

Purau Bay

Ripapa T1

Ripapa T2

Ripapa T3 R

ipap

Ha

Ha

Ha

Ha

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

NN

N (m

g/L)

Figure 2-5: Nitrite-nitrate concentrations (mg/L) at sites in Lyttelton Harbour/Whakaraupō in four time periods box = interquartile range, whisker ends = % and 95%iles, = outlier values, = extreme values, dashed line = line of fit of medians

NOTE Extreme value at Purau Bay T1 not shown

T1 = 1992-1993

T2 = 1993-1994

T3 = 2002-2003

T4 = 2007-2008


arbour/ Whakaraupō

Environment C


13

Gove

Gove

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Charte

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Charte

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Quail-R

Corsair B

Corsair B

Corsair B

Corsair B

Church B

In

In

In

In

Purau Bay

Purau Bay

Purau Bay

Purau Bay

Ripapa T1

Ripapa T2

Ripapa T3 R

ipap

Ha

Ha

Ha

Ha

0.0

0.1

0.2

0.3

0.4

0.5

TN (m

g/L)

Figure 2-6: Total nitrogen concentrations (mg/L) at sites in Lyttelton Harbour/Whakaraupō in four time periods box = interquartile range, whisker ends = % and 95%iles, = outlier values, = extreme values, dashed line = line of fit of medians

T1 = 1992-1993

T2 = 1993-1994

T3 = 2002-2003

T4 = 2007-2008

14 Environm


eport


arbour/ Whakaraupō

Gove

Gove

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Church B

In

In

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In

Purau Bay

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Purau Bay

Purau Bay

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Ripapa T2

Ripapa T3 R

ipap

Ha

Ha

Ha

Ha

0.00

0.01

0.02

0.03

0.04

0.05

DR

P (mg/L)

Figure 2-7: Dissolved reactive phosphorus concentrations (mg/L) at sites in Lyttelton Harbour/Whakaraupō in four time periods box = interquartile range, whisker ends = % and 95%iles, = outlier values, = extreme values, dashed line = line of fit of medians

T1 = 1992-1993

T2 = 1993-1994

T3 = 2002-2003

T4 = 2007-2008


arbour/ Whakaraupō

Environment C


15

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In

In

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Ha

Ha

Ha

0.00

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0.04

0.06

0.08

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0.16

TP (mg/L)

Figure 2-8: Total phosphorus concentrations (mg/L) at sites in Lyttelton Harbour/Whakaraupō in four time periods box = interquartile range, whisker ends = % and 95%iles, = outlier values, = extreme values, dashed line = line of fit of medians

T1 = 1992-1993

T2 = 1993-1994

T3 = 2002-2003

T4 = 2007-2008



Figure 2-9: Chlorophyll-a concentrations (µg/L) at sites in Lyttelton Harbour/Whakaraupō in two time periods

box = interquartile range, whisker ends = % and 95%iles, = outlier values, = extreme values, dashed line = line of fit of medians T3 = 2002-2003 T4 = 2007-2008

Figure 2-10: Total suspended solids concentrations (mg/L) at sites in Lyttelton Harbour/Whakaraupō in 2007- 2008 (T4)

box = interquartile range, whisker ends = % and 95%iles, , = outlier values, = extreme values, dashed line = line of fit of medians

Gove

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Charte

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Church B

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Chlorophyll-a (ug/L)

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a

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TSS (mg/L)



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In

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Purau Bay

Ripapa T3 R

ipap

Ha

Ha

0

10

20

30

40

50

60

Turbidity (NTU

)

Figure 2-11: Turbidity (NTU) at sites in Lyttelton Harbour/Whakaraupō in two time periods box = interquartile range, whisker ends = % and 95%iles, = outlier values, = extreme values, dashed line = line of fit of medians T3 = 2002-2003 T4 = 2007-2008

Figure 2-12: Salinity (ppt) at sites in Lyttelton Harbour/Whakaraupō in 2007- 2008 (T4) box = interquartile range, whisker ends = % and 95%iles, = outlier values, = extreme values,

dashed line = line of fit of medians

Gove

Charte

Quail-R

Corsair B

Church B

In

Purau Bay

Ripap

Ha

28

29

30

31

32

33

34

35

36

Salinity (ppt)



Figure 2-13: Dissolved oxygen (% saturation) at sites in Lyttelton Harbour/Whakaraupō in 2007- 2008 (T4)

box = interquartile range, whisker ends = % and 95%iles, = outlier values, = extreme values, dashed line = line of fit of medians

2.4 Parameter concentrations between sites The Wilcoxon two-tailed sign test was used to investigate whether there were significant differences in parameter concentrations between sites in each time period. The results of the Wilcoxon two-tailed sign test are presented in Appendix 5. The results from the 2004 report (Bolton-Ritchie, 2004) are combined into one table in Appendix 5 while the results for 2007-2008 are in a separate table.

Nitrite-nitrate nitrogen (NNN) NNN concentrations were significantly higher at the inner port entrance than at a number of other sites in 1992-1993, 2002-2003 and 2007-2008 but not over 1993-1994 (refer Appendix 5). The other significant differences in NNN concentrations between sites were:

• higher concentrations in Charteris Bay than in Governors Bay in 1993-1994; • higher concentrations in Corsair Bay than in Governors Bay, Purau Bay and at Ripapa in

2002-2003; • higher concentrations in Purau Bay than at Quail-Rapaki in 2007-2008; • higher concentrations at the harbour entrance than at Quail-Rapaki, Church Bay and Ripapa-

Battery in 2007-2008.

Gove

Charte

Quail-R

Corsair B

Church B

In

Purau Bay

Ripap

Ha

80

85

90

95

100

105

110

DO

%saturation



Ammonia nitrogen (NH3N) NH3N concentrations were significantly higher at the inner port entrance than at some of the other sites in 1993-1994 and 2007-2008 (refer Appendix 5). The other significant differences in NH3N concentrations between sites were:

• higher concentrations in Charteris Bay and Corsair Bay than in Purau Bay in 1993-1994; • higher concentrations at the harbour entrance than at Ripapa in 2002-2003; • higher concentrations in Charteris Bay, Church Bay and Purau Bay than in Governors Bay in

2007-2008. Total nitrogen (TN) TN concentrations were significantly higher at upper harbour sites than at the harbour entrance in 1992-1993 and 2007-2008 (refer Appendix 5). However, in 1993-1994 TN concentrations at the harbour entrance were significantly higher than in Charteris Bay, at the inner port entrance and Purau Bay. Concentrations at the upper harbour sites of Governors Bay and Corsair Bay were also significantly higher than those at Ripapa in 1992-1993 and 2002-2003 and in 2007-2008 concentrations at Governors Bay were significantly higher than those at Ripapa-Battery. The other significant differences in TN concentrations between sites were:

• higher concentrations in Charteris Bay than in Purau Bay in 2007-2008; • higher concentrations in Corsair Bay than in Charteris Bay, at the inner port entrance and

Purau Bay in 1993-1994. Dissolved reactive phosphorus (DRP) DRP concentrations were significantly higher in Governors Bay than at many of the other sites in 1992-1993, 2002-2003 and 2007-2008 (refer Appendix 5). They were also higher in Governors Bay than at Purau and Ripapa in 1993-1994. The other significant differences in DRP concentrations between sites were:

• lower concentrations in Purau Bay, Ripapa/Ripapa-Battery and the harbour entrance than in Corsair Bay and at the inner port entrance over all sampling periods;

• higher concentrations at Charteris Bay than in Purau Bay and at Ripapa in 1993-1994 and 2002-2003. Concentrations were also higher in Charteris Bay than in Purau Bay in 2007-2008;

• higher concentrations in Governors Bay, Quail-Rapaki and Corsair Bay than in Church Bay in 2007-2008;

• lower concentrations at the harbour entrance than at all other sites in 2007-2008. Total phosphorus (TP) TP concentrations in Governors Bay were significantly higher than at all other sites in 1993-1994 and almost all other sites in 2007-2008 (refer Appendix 5). They were also higher than those at a number of other sites in both 1992-1993 and 2002-2003. The other significant differences in TP concentrations between sites were:

• higher concentrations in Corsair Bay than at Ripapa in 1993-1994; • higher concentrations at the inner port entrance than in Purau Bay and Ripapa in 1993-1994; • higher concentrations in Charteris Bay than at many other sites in 2007-2008; • higher concentrations at Quail-Rapaki than in Purau Bay and at Ripapa-Battery in 2007-2008; • lower concentrations at the harbour entrance than at all other sites in 2007-2008.

Chlorophyll-a (measured in 2002-2003 and 2007-2008) Chlorophyll-a concentrations at the inner port entrance were significantly higher than those at many of the other sites in 2002-2003 while in 2007-2008 they were only significantly higher than those in Church Bay (refer Appendix 5). Concentrations in Corsair Bay were significantly higher than those at some of the other sites in both 2002-2003 and 2007-2008. The other significant differences in chlorophyll-a concentrations between sites were:

• higher concentrations at the harbour entrance than in Purau Bay in 2002-2003; • higher concentrations at Ripapa-Battery than in Charteris Bay, Church Bay, Purau Bay and at

the harbour entrance in 2007-2008; • higher concentrations at Quail-Rapaki than in Charteris Bay in 2007-2008.



Turbidity (measured in 2002-2003 and 2007-2008) Water turbidity at upper harbour sites was typically significantly higher than at the inner port entrance and the harbour entrance in both sampling periods (refer Appendix 5). The upper harbour sites were also more turbid than Purau Bay in 2007-2008 but this was not the case in 2002-2003. Charteris Bay and Governors Bay were significantly more turbid than Ripapa in 2002-2003 while in 2007-2008 Governors Bay and Corsair Bay were more turbid than Ripapa-Battery. Total suspended solids (TSS) (measured in 2007-2008) Total suspended solids concentrations at upper harbour sites were significantly higher than at the inner port entrance, Purau Bay and the harbour entrance (refer Appendix 5). Ripapa-Battery TSS concentrations were also significantly higher than at the inner port entrance and the harbour entrance but not in Purau Bay. Ripapa-Battery TSS concentrations were not significantly different to concentrations in Charteris Bay, Quail-Rapaki and Corsair Bay but significantly lower than those in Governors Bay and Church Bay. Dissolved oxygen saturation (DO sat.) (measured in 2007-2008) DO saturation at the harbour entrance was significantly higher than at Quail-Rapaki, Corsair Bay, Church Bay, Purau Bay and Ripapa-Battery (refer Appendix 5).

2.5 Seasonality Seasonality is the change in parameter concentration with the seasons. For NNN, DRP, TP and chlorophyll-a there was a significant difference in concentration between seasons at one or more sites. Nitrite-nitrate nitrogen There was a significant difference in NNN concentrations between seasons in Governors Bay, Corsair Bay, at the inner port entrance, Purau Bay and the harbour entrance but not in Charteris Bay. Concentrations were highest in winter and lowest in summer (Figure 2-14). Dissolved reactive phosphorus There was a significant difference in DRP concentrations between seasons at all six sites. Concentrations were higher in autumn and winter than in spring and summer; the lowest concentrations occurred in spring (Figure 2-15). Total Phosphorus There was a significant difference in TP concentrations between seasons at Charteris Bay, the inner port entrance, Purau Bay and the harbour entrance but not at Governors Bay and Corsair Bay. Concentrations were higher in autumn and winter than in spring and summer; the lowest concentrations occurred in spring (Figure 2-16). Chlorophyll-a There was a significant difference in chlorophyll-a concentrations between seasons at the inner port entrance only. This seasonality consisted of higher concentrations in summer than in the other seasons (Figure 2-17). Although there were not significant differences in chlorophyll-a concentrations between seasons at the other five sites, the concentrations at Governors Bay, Charteris Bay, Corsair Bay and Purau Bay were typically higher in summer than in the other seasons (Figure 2-17). This difference did not occur at the Harbour entrance.



Figure 2-14: Seasonality of nitrite-nitrate nitrogen concentrations horizontal bar = median , box = interquartile range, whisker ends = % and 95%iles o = outlier values, = extreme values

winter spring summer autumn

Season

0.00

0.05

0.10

0.15

0.20

NN

N c

once

ntra

tion

(mg/

L)

Governors Bay *


Season

0.00

0.05

0.10

0.15

0.20

NN

N c

once

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tion

(mg/

L)

Corsair Bay **


Season

0.00

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N c

once

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tion

(mg/

L)

Inner port entrance **


Season

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0.25

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N c

once

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tion

(mg/

L)Purau Bay *


Season

0.00

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N c

once

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tion

(mg/

L)

Harbour entrance ***

* significant difference between seasons at p<0.05 ** significant difference between seasons at p<0.01 *** significant difference between seasons at p<0.001




Season

0.00

0.01

0.02

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0.05

DR

P co

ncen

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ion

(mg/

L)

Governors Bay *


Season

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DR

P co

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Season

0.00

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P co

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(mg/

L)Inner port entrance **


Season

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Purau Bay **


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P co

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Harbour entrance ***


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0.00

0.01

0.02

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0.04

0.05

DR

P co

ncen

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ion

(mg/

L)

Charteris Bay **

Figure 2-15: Seasonality of dissolved reactive phosphorus concentrations horizontal bar = median , box = interquartile range, whisker ends = % and 95%iles o = outlier values, = extreme values

* significant difference between seasons at p<0.05 ** significant difference between seasons at p<0.01 *** significant difference between seasons at p<0.001




Season

0.00

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0.12

0.16

TP concentra


Season

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TP concentra


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0.04

0.08

0.12

0.16

TP concentra


Season

0.00

0.04

0.08

0.12

0.16TP

concentratio

Figure 2-16: Seasonality of total phosphorus concentrations horizontal bar = median , box = interquartile range, whisker ends = % and 95%iles o = outlier values, = extreme values

* significant difference between seasons at p<0.05 ** significant difference between seasons at p<0.01

Harbour entrance *

Charteris Bay * Inner port entrance **

Purau Bay **




Season

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Charteris Bay

Figure 2-17: Seasonal differences in chlorophyll-a concentrations horizontal bar = median , box = interquartile range, whisker ends = % and 95%iles o = outlier values, = extreme values * significant difference between seasons at p<0.05



2.6 Nutrient concentrations at each site over time Nutrient data were analysed to investigate if there were increases or decreases in concentration at a site between time periods (1990s and 2000s). There were no significant differences in NH3N and NNN concentrations between the 1990s and the 2000s, at any of the sites. There were significant differences (at p<0.05) in TN, DRP and TP concentrations between time periods at one or more of the sites. Total nitrogen TN concentrations at the inner port entrance were significantly higher (p = 0.04) in the 2000s than in the 1990s (Figure 2-18). At the inner port entrance the mean TN concentration in the 1990s was 0.170 mg/L and in the 2000s it was 0.227 mg/L. There were no significant differences in TN concentrations over time at the other five sites. Dissolved reactive phosphorus DRP concentrations at the harbour entrance were significantly lower (p = 0.035) in the 2000s than in the 1990s (Figure 2-18). At the harbour entrance the mean DRP concentration in the 1990s was 0.016 mg/L and in the 2000s it was 0.012 mg/L. There were no significant differences in DRP concentrations over time at the other five sites. Total phosphorus TP concentrations were significantly lower in the 2000s than in the 1990s at Governors Bay (p = 0.03), the inner port entrance (p = 0.04), Purau Bay (p = 0.04) and the harbour entrance (p = 0.003) (Figure 2-18). At Governors Bay the mean TP concentration in the 1990s was 0.055 mg/L and in the 2000s it was 0.041 mg/L. At the inner port entrance the mean TP concentration in the 1990’s was 0.040 mg/L and in the 2000’s it was 0.031 mg/L. At Purau Bay the mean TP concentration in the 1990s was 0.034 mg/L and in the 2000s it was 0.030 mg/L. At the harbour entrance the mean TP concentration in the 1990s was 0.035 mg/L and in the 2000s it was 0.024 mg/L. There were no significant difference in TP concentrations over time at Charteris Bay and Corsair Bay.



1990's 2000's0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

TP c

once

ntra

tion

(mg/

L)

1990's 2000's0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16TP

con

cent

ratio

n (m

g/L)

1990's 2000's0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

TP c

once

ntra

tion

(mg/

L)

1990's 2000's0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

TP c

once

ntra

tion

(mg/

L)

Figure 2-18: Differences in TN, DRP and TP concentrations (mg/L) over time horizontal bar = mean , box = Standard error , whisker ends = Standard Deviation = outlier values, = extreme values

1990's 2000's0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

TN concentr

1990's 2000's0.000

0.005

0.010

0.015

0.020

0.025

0.030

DR

P concen

TP Purau Bay

TP Governors Bay TP Inner port entrance

TP Harbour entrance

TN Inner port entrance DRP Harbour entrance



2.7 Parameter concentrations between years Nutrient data were used to investigate similarities and differences in water quality at and between sites over time. The data were used to produce MDS ordinations. On an MDS ordination sites are plotted in a spatial array, and the closer together the sites the more similar they are with regard to the parameters used to generate the ordination. The resulting MDS ordination has been presented using two groupings (year and yearseason) of the same data (Figure 2-19 – 2-20). The stress value is provided on each plot. Stress is a measure of the accuracy of the 2-dimensional ordination of points on the MDS plot in representing the actual values in the similarity matrix (Clarke and Warwick, 2001). The stress value of 0.09 indicates that the ordination is a good representation of the similarities between sites. Grouping by year The grouping of the points by years allows for the assessment of the overall similarity of nutrient concentrations between years (Figure 2-19). For each year there are 24 points, that is, six sites with the four seasons at each site. The plot shows that:

in 2002-2003 nutrient concentrations at the sites were more similar than they were in the other years, i.e. less of a spread of points on the plot.

the 1993-1994 and 2002-2003 nutrients concentrations were similar the 2007-2008 nutrient concentrations were more similar to those from 1992-1993 than from

the other two time periods. Grouping by year and season The grouping of points by year and season allows for an assessment of the similarity of nutrient concentrations between years for different seasons (Figure 2-20). The plot shows the following:

similarity in nutrient concentrations in winter between 1993-1994 and 2002-2003 and between 1992-1993 and 2007-2008

Spring nutrient concentrations in 2002-2003 were different to those in the other three years Spring nutrient concentrations in 2007-2008 were similar to those in 1992-1993 Summer nutrient concentrations in 2007-2008 were different to those in the other three years Autumn nutrient concentrations in 1992-1993 and 1993-1994 were similar Autumn nutrient concentrations in 2007-2008 were typically different to those in the other three

years

2.8 Factors affecting harbour water quality There were significant spatial and temporal differences in parameter concentrations. The following factors may account for differences in parameter concentrations between sites.

• Freshwater inputs and sampling site proximity to an input • Wastewater discharges and sampling site proximity to a discharge point • Proximity of a site to the shore • Water depth at the time of sampling • Seabed sediment type • Inputs from the inner port and sampling site proximity to the port

These factors are addressed in the following chapters. The weather, i.e. rainfall and wind conditions (wind direction and wind speed) could account for differences in parameter concentrations over time. Differences in the volumes and quality of wastewater discharged into the harbour and changes in land use over time could also have an influence.



YearSeason1winter1spring1summer1autumn2winter2spring2summer2autumn3winter3spring3summer3autumn4winter4spring4summer4autumn

2D Stress: 0.09

Figure 2-19: MDS ordination of mean nutrient concentrations for each season, in each year at each site, points grouped by year Year 1 – 1992-1993, Year 2 – 1993-1994, Year 3 – 2002-2003, Year 4 – 2007-2008

Figure 2-20: MDS ordination of mean nutrient concentrations for each season, in each year at each site, points grouped by seasons within years

Year 1 – 1992-1993, Year 2 – 1993-1994, Year 3 – 2002-2003, Year 4 – 2007-2008

Year1234

2D Stress: 0.09



2.8.1 Rainfall Rainwater is freshwater than can dissolve soluble compounds including nutrients and entrain soil particles as it flows across the land surface. The rainwater eventually ends up in the sea either via the waterways or as flows directly off the land. The total volume of rainfall does vary from year to year and hence the quantity of land derived nutrients that reaches the sea likely varies from year to year. The total rainfall, recorded by Environment Canterbury at Coopers Knob, for each of the years of sampling is given in Table 2.2. Coopers Knob is on the summit of the harbour rim between Governors Bay and Head of the Bay (Figure 1-1). The data from this site provides a general picture of the difference in rainfall volume between years. However, it is acknowledged that rainfall around the harbour varies with location.

Table 2.2: Total rainfall (mm) at Coopers Knob over each year of sampling

2002-2003 was a comparatively dry year with only 72% of the rainfall of 1992-1993. 2007-2008 had 82% of the rainfall of 1992-1993. The influence of rainfall on harbour water quality is presented in chapter 3.

2.8.2 Wind Wind speed influences the evaporation of water from the sea surface. Wind direction and speed influence the water mixing processes within the harbour. Within Lyttelton Harbour/Whakaraupō tides, wind and long-term equilibrium mixing processes drive the water circulation patterns (Spigel, 1993). The wind data collected by NZ Metservice at a recorder located in the inner port (Map reference M36:878 332) for each of the years of sampling are summarised in Appendix 6. Wind direction Within the harbour east-north-easterly and south-westerly winds predominate with some easterlies and wind from other directions. The frequency of wind from any particular direction varied between years with the wind direction plot for 2007-2008 notably different from those for the other three sampling periods. Wind speed The percentage occurrence of wind speeds varied between sampling years. However, wind speeds in 2007-2008 were considerably different from those in the other years. The wind patterns for 2007-2008 were different from those in the other time periods. As a consequence water circulation within the harbour in 2007-2008 may have been different from that in other sampling years. A detailed analysis of data was carried out to investigate the influence of wind speed and direction on nutrient concentrations. There was no evidence that wind speed and wind direction accounted for the differences in nutrient concentrations between sites. It is likely that wind influences turbidity and TSS concentrations through wind generated wave disturbance of the seabed. This influence is explored in detail in chapter 4.

Total rainfall (mm)

1992-1993 912

1993-1994 867.7

2002-2003 658

2007-2008 751.5



2.9 Discussion Water quality through the harbour There were significant differences in NH3N, NNN, TN, TP, DRP, chlorophyll-a and TSS concentrations and turbidity and DO % saturation between sites. For NH3N and NNN there was no down-the-harbour pattern in concentrations. However, for both nutrients there were significant differences in concentrations between sites. There was no pattern to the differences between sites in the different years of sampling except for higher concentrations at the inner port entrance than at other harbour sites. Freshwater inputs via the streams and stormwater discharges are considered the source of much of the NNN while the wastewater discharges are a significant source of NH3N to harbour water. Freshwater and wastewater inputs are investigated in Chapter 3 of this report. For TN there were also significant differences in concentrations between sites with no pattern to the differences between sites in the different years of sampling. However, in two of the years TN concentrations at upper harbour sites were significantly higher than at the harbour entrance while on one of the years concentrations at the harbour entrance were significantly higher than at one of the upper harbour sites. That is, there is considerable variability in TN concentrations within the harbour. There were significantly higher concentrations of NNN, NH3N at the inner port entrance than at other sites in different sampling periods. The results suggest inputs of these nutrients to this site with the potential sources being the Port of Lyttelton, the adjacent marina, stormwater and wastewater effluent from the Sticking Point outfall. Year-long monitoring at sites within the inner port in 1999-2000 showed that nutrient concentrations were higher, and the range in concentration of each nutrient was larger than at sites in greater Lyttelton Harbour/Whakaraupō (Bolton-Ritchie, 2004). This variation in nutrient concentrations indicates site-specific sources of nutrients, and irregular nutrient inputs at various locations, within the inner port. The potential source of irregular inputs includes:

• Washing down of boat decks; • Settling of dust (including phosphate, fertiliser, gypsum, sulphur and cement) from the

bulk cargo handling area of the port; • Spillage events in the port, e.g. spillage of fertiliser; • Illegal discharges from vessels within the harbour.

There are at least eight stormwater outlets around the port and two just outside the western breakwater at the inner port entrance (Paul Kelly, Lyttelton Port Company, pers. com.). The water discharged via these outlets is stormwater from Lyttelton township, stormwater from the operational area of the port, and water from channelised streams in the immediate area. For TP and DRP concentrations typically decreased with increasing distance down the harbour, i.e. from the upper harbour to the harbour entrance. This pattern suggests that there are more inputs of phosphorus in the upper, than further down the, harbour. These inputs will be from streams, general land runoff and discharges. There are more streams and there will be more general runoff from land in the upper harbour, where there is land on three sides, than in the mid and outer harbour. The volcanic rock of Banks Peninsula is phosphorus rich and a source of phosphorus to stream water and hence harbour water (Lynn, 2005). Treated wastewater is also a source of phosphorus. It should also be noted that the water in the upper harbour is shallower than in the mid to outer harbour. That is, there is less water to dilute the inputs from streams, land runoff and discharges, than occurs in the mid to outer harbour. For turbidity and TSS, concentrations typically decreased with distance down the harbour. Turbidity is a relative measure of the light scattering by suspended particles in water and indicates cloudiness or visual clarity of the water. Water in the upper harbour is typically not as clear as water in the mid to outer harbour. Total suspended solids (TSS) are a measure of the quantity of particles in water. Such particles include stirred up seabed sediment, soil from the land, detritus, i.e. dead plant or animal material and live organisms. The quantity of particles in harbour water decreases with distance down the harbour. The clearest or least turbid water and the water containing the least amount of particles occurred at the harbour entrance. With land on three sides there are more sources of soil particles and more streams transporting soil particles to the harbour, in the upper part of, than to the mid and outer harbour. There is also less water to dilute the inputs from streams and land runoff into the upper, than into the mid to outer, harbour. The upper harbour is shallower than the mid to outer harbour. In shallow



water wind driven waves re-suspend seabed sediments into the water column. The deeper the water the less likely that seabed sediments will be re-suspended by wind forcing and the less likely re-suspended sediment will be in surface water. Chlorophyll-a concentrations varied between sites, but were typically lower at the upper most harbour sites than at sites in the mid to outer harbour. With chlorophyll-a concentration a measure of phytoplankton (plant plankton) abundance these results indicate phytoplankton are less abundant in the upper most part of the harbour than in the mid and outer harbour. Phytoplankton require adequate light to function and grow. The turbid upper Lyttelton Harbour//Whakaraupō water with its elevated TSS concentrations could be limiting the abundance of phytoplankton in this part of the harbour. The DO % saturation of the water varied between sites with water at the harbour entrance being significantly more saturated with DO than that at many of the sites within the harbour. The primary source of DO in surface water is oxygen from the atmosphere with the release of oxygen by phytoplankton and seaweeds another source. Micro-organisms and animals living in the water column, and in and on the seabed, use the oxygen. The results indicate that either more oxygen is entering the water at the harbour entrance than at other sites or more oxygen is being used by micro-organisms and other animals at sites within the harbour than at the harbour entrance. However, this is an oversimplified explanation as DO saturation is also influenced by water temperature (colder water has higher % saturation than warmer water), plant productivity and may vary with depth in the water column. For example the lower DO % saturation at shallow upper harbour sites than at the harbour entrance may be due to:

• warmer water at the shallower sites than the deeper sites, particularly in summer. • less DO production by phytoplankton at upper harbour sites than at the harbour entrance as a

consequence of the higher TSS concentrations in upper harbour water. • DO consumption by seabed dwelling organisms affects the surface water at shallow sites but

not deep sites. At the deep sites such as the harbour entrance the influence of seabed dwelling organisms on DO % saturation may extend several meters into the water column above the seabed but not to the sea surface.

Water quality over time It is well recognised that the dissolved nutrients NNN and DRP have a seasonal pattern and this was the case at many of the Lyttelton Harbour//Whakaraupō sites. However, these seasonal patterns occurred over some but not all of the years of sampling. The seasonality of these nutrients is likely a consequence of their use by phytoplankton. However, the quantity of these nutrients flowing into the harbour from the streams also has a seasonal component. This is because the quantities discharged are influenced by rainfall with typically more rainfall over winter than summer months. With respect to phytoplankton use of NNN and DRP, the phytoplankton takes up these dissolved nutrients and uses them for growth and productivity in spring when water temperatures and sunlight hours and intensity increase. With declining water temperatures and sunlight hours and intensity in mid-late autumn, the phytoplankton die thereby releasing NNN and DRP back into the water. Chlorophyll-a concentration (phytoplankton abundance) exhibited seasonality at sites in the harbour. The seasonal difference consisted of higher concentrations in summer than the other seasons. The absence of phytoplankton seasonality at the harbour entrance may be a consequence of the influence of water from various sources, that is, oceanic water or water from the Waimakariri River or water exiting the harbour, on phytoplankton abundance at this site. There were significant differences in TN, DRP and TP concentrations but not NH3N and NNN concentrations between the 1990’s and 2000’s at one or more of the sites. For DRP and TP there was a significant decrease in concentration over time but for TN there was a significant increase in concentration at the inner port entrance between the 1990’s and 2000’s which suggests a decline in water quality over time. The mean TN concentration at this site in the 1990’s was 0.170 mg/L and in the 2000s it was 0.227 mg/L. Total nitrogen is the sum of ammonia nitrogen, nitrate-nitrite nitrogen and total organic nitrogen (TON). There was no significant increase in NH3N or NNN at this site over time which suggests a significant increase in TON over time. Total organic nitrogen consists of dissolved and particulate organic forms. Particulate organic nitrogen is a measure of the nitrogen in living plankton and dead particulate matter while dissolved organic nitrogen can consist of simple (amino



acids) to complex nitrogen compounds. As no organic nitrogen analyses were undertaken it is not possible to determine if the increase in TON over time was as a result of an increase in dissolved or particulate or both, over time. The 1993-1994 and 2002-2003 nutrients concentrations were similar while the 2007-2008 nutrient concentrations were more similar to those from 1992-1993 than from the other two time periods. Differences in annual rainfall do not account for the between-year differences in nutrient concentrations. For example, there was 912 mm rain in 1992-1993 and 751.5 mm in 2007-2008, an overall difference of 110.5 mm between years. However, the analysis of annual rainfall does not take into account rainfall volume in the days prior to water sampling and the intensity of rainfall events. These two aspects of rainfall could well be those that are relevant to nutrient concentrations in harbour water. The 2002-2003 nutrient concentrations were more similar between sites than they were in the other years. There was less rainfall in 2002-2003 than in the other years sampled which may account for this result. There was no evidence that wind speed and wind direction accounted for differences in nutrient concentrations between sites.



3 Nutrient inputs to harbour water This chapter presents information on nutrient concentrations in stream water and wastewater discharges and their impacts on harbour water nutrient concentrations. The impact of the input of stream water on harbour water salinity is also investigated. Inputs of total suspended solids and micro-organisms are dealt with in later chapters of this report.

3.1 Streams/creeks flowing to the harbour The streams flowing into Lyttelton Harbour/Whakaraupō are shown in Figure 3-1. Many of these are ephemeral but a number have water flows all year round, albeit with low flows over summer months.

Figure 3-1: Harbour streams with stream and adjacent harbour sampling sites marked Black dot - harbour sampling site

Green dot – stream sampling site



3.1.1 Nutrient concentrations in harbour streams There are limited nutrient data for the Lyttelton Harbour/Whakaraupō streams. However, six (Rapaki Stream, Zephyr Stream, Living Springs Creek, Teddington Stream, Te Wharau Stream (Figure 3-2) and Purau Stream) (Figure 3-1) have been sampled by Environment Canterbury since September 2007. Sites were sampled quarterly between September 2007 and March 2008 sites then monthly between July and December 2008. The summary results are given in Table 3.1. Nutrient concentrations over time in each of the streams are shown in Appendix 7 while details of the rainfall volumes in the five days preceding each sampling run are presented in Appendix 8.

Figure 3-2: Te Wharau Stream and its catchment, Charteris Bay

The data show that:

1. the highest median concentrations of: • NH3N, NNN and TN occurred in Livings Spring Creek; • DRP and TP occurred in Rapaki Stream.

2. the highest maximum concentrations of: • NH3N, TN and DRP occurred in Livings Spring Creek; • NNN occurred in the Zephyr Stream; • TP occurred in Rapaki Stream.

3. the median NH3N, NNN and TN concentrations in Livings Spring Creek are about twice that in any of the other waterways.

4. the maximum TP concentration in Rapaki Stream is about twice that in any of the other waterways.

5. peaks in NNN and TN concentrations occurred at all sites on one or more sampling occasion (Appendix 7). The peaks in concentration on 20 August 2008 are likely a result of the 14 mm of rainfall on the day prior to sampling. The peak in TN concentration on 19 December 2007 at all sites likely result from the 15 mm of rainfall on the day prior to sampling.

The results indicate that rainfall volume on the day prior to sampling can, but did not always, result in elevated concentrations of some nutrients in stream/creek water. However, while there were marked differences in nutrient concentrations between some sites with rainfall there were not:



• peaks in concentrations on 19 September, 2008 following 18 mm of rainfall. • peaks in concentrations of most nutrients on 19 December 2007 following 15 mm of

rainfall. It is possible that rainfall intensity has an influence on nutrient concentrations. There was 14 mm of rain on 19 August 2008 with 10.5 mm over a two hour period. On the 18th of September there was 18 mm of rain but the highest intensity was 4 mm over a two hour period. Stream water flows were not measured in tandem with water quality sampling. Hence the mass load of nutrients discharged into the harbour per day and per year from each stream could not be calculated.

Table 3.1: Summary of nutrient concentrations in six harbour streams, September 2007 – December 2008

n = number of samples

Rap

aki S

trea

m

Zeph

yr S

trea

m

Livi

ng S

prin

gs

Cre

ek

Tedd

ingt

on

Stre

am

Te W

hara

u St

ream

Pura

u St

ream

Minimum < 0.005 0.005 0.03 0.01 0.009 < 0.005Mean 0.016 0.013 0.064 0.029 0.015 0.013SD 0.011 0.007 0.035 0.018 0.006 0.006Median 0.013 0.011 0.050 0.023 0.015 0.012Maximum 0.037 0.024 0.15 0.065 0.028 0.026

Minimum < 0.005 0.04 0.27 0.066 0.069 0.023Mean 0.167 0.293 0.528 0.197 0.271 0.195SD 0.254 0.303 0.183 0.210 0.240 0.211Median 0.029 0.290 0.475 0.110 0.175 0.125Maximum 0.76 1 0.83 0.66 0.77 0.7

Minimum 0.12 0.18 0.49 0.28 < 0.08 0.04Mean 0.534 0.529 0.909 0.551 0.389 0.282SD 0.340 0.383 0.366 0.233 0.279 0.258Median 0.45 0.44 0.825 0.45 0.345 0.2Maximum 1.2 1.4 1.5 1 0.81 0.77

Minimum 0.008 0.02 0.021 0.013 0.015 0.011Mean 0.035 0.027 0.038 0.023 0.023 0.020SD 0.017 0.008 0.016 0.009 0.010 0.009Median 0.035 0.022 0.033 0.020 0.021 0.017Maximum 0.056 0.042 0.069 0.037 0.044 0.037

Minimum 0.077 0.041 0.071 0.045 0.027 0.021Mean 0.203 0.061 0.109 0.078 0.045 0.033SD 0.154 0.021 0.035 0.026 0.019 0.014Median 0.12 0.051 0.0975 0.084 0.0375 0.025Maximum 0.46 0.096 0.18 0.11 0.088 0.059n 10 9 10 7 10 10

Total phosphorus

Ammonia nitrogen

Nitrite-nitrate nitrogen

Total nitrogen

Dissolved reactive phosphorus



3.1.2 Impacts of stream/creek inputs on harbour water salinity Fresh water flowing into the harbour dilutes sea water; a measure of the amount of dilution is shown by the salinity data. Salinity was only measured over 2007-2008. The salinity data for this time period are summarised in Appendix 4 and presented in Figure 3-3. In 2007 salinity at all sites was lowest in winter and early spring, increased in late spring to be highest in December (Figure 3-3). High salinities occurred through until May 2008 at all sites.

28

29

30

31

32

33

34

35

36

1-Ju

l-07

16-J

ul-0

7

31-J

ul-0

7

15-A

ug-0

7

30-A

ug-0

7

14-S

ep-0

7

29-S

ep-0

7

14-O

ct-0

7

29-O

ct-0

7

13-N

ov-0

7

28-N

ov-0

7

13-D

ec-0

7

28-D

ec-0

7

12-J

an-0

8

27-J

an-0

8

11-F

eb-0

8

26-F

eb-0

8

12-M

ar-0

8

27-M

ar-0

8

11-A

pr-0

8

26-A

pr-0

8

11-M

ay-0

8

26-M

ay-0

8

10-J

un-0

8

Date

Salin

ity (p

pt)

Charteris BayGovernors BayQuail-RapakiCorsair BayChurch BayInner port entrance Purau BayRipapa-Battery Harbour entrance

Figure 3-3: Salinity (ppt) at harbour sites, 2007-2008

The variability in salinity between sampling sites on a given day ranged between 0.5 and 2.2 ppt. There was a salinity variability of more than 1.1 ppt between sites on 9 July, 6 August, 8 October, and 3 December 2007 and 23 January and 12 May 2008. These differences in salinity were likely as a result of rainfall, stream water volumes and water depth. For example differences on 6 August were likely due to the rainfall events in the days prior to sampling (On 30 July 28 mm, on 4 August 12.5 mm and on 5 August 10 mm of rain was recorded at Coopers Knob.). However, on 8 October salinity variability between sites was as a consequence of low salinity at the harbour entrance. This suggests a freshwater plume from a large river, such as the Waimakariri, affected the water at this site on this occasion.

3.1.3 Impact of stream inputs on harbour water nutrient concentrations Nutrient concentrations at the Charteris Bay, Governors Bay, Corsair Bay, Church Bay and Purau Bay sites have the potential to be influenced by water flowing out of one or more nearby streams (Figure 3-1). The distance from these harbour sites to nearby streams is provided in Appendix 9. To investigate the influence of rainfall and hence increased freshwater flows on nutrient harbour concentrations, nutrient concentrations at the five sites were plotted against pre-sampling rainfall quantity. This analysis was limited to NNN, TN and DRP concentrations in harbour water. Ammonia nitrogen and TP were not included because:

• wastewater discharges are a significant contributor of NH3N to harbour water and are in proximity to two of the harbour sites.



• TP concentration in harbour water is highly correlated to TSS concentration. TP concentrations in the water could be as a result of re-suspension of seabed sediment or inputs from land.

The total rainfall at Coopers Knob in the four days and the hours prior on the day of sampling were used.

For TN and DRP there was no increase in harbour water concentrations as rainfall quantity increased (Figure 3-4). For NNN the highest concentrations appear to result from very heavy rainfall, i.e. 50 mm prior to sampling. There was no correlation between NNN concentration and rainfall for rainfall quantities less than 20 mm. Due to a lack of data it was not possible to determine if there was a relationship between NNN concentration and rainfall for rainfall quantities between 20 and 50 mm. An analysis of the data determined that distance from a waterway did not appear to account for differences in TN, NNN and DRP concentrations between sites.



Figure 3-4: The influence of pre-sampling rainfall quantity on NNN, TN and DRP concentrations at five harbour sites

0 10 20 30 40 50Rainfall (mm)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

NN

N c

once

ntra

tion

(mg/

L)

Corsair Governors Charteris Purau Church

0 10 20 30 40 50Rainfall (mm)

0.0

0.1

0.2

0.3

0.4

0.5

TN c

once

ntra

tion

(mg/

L)


0 10 20 30 40 50Rainfall (mm)

0.00

0.01

0.02

0.03

0.04

0.05

DR

P c

once

ntra

tion

(mg/

L)




3.2 Wastewater discharges Treated wastewater is discharged into Lyttelton Harbour/Whakaraupō via three outfalls, Lyttelton, Governors Bay and Diamond Harbour (Figure 3-5). The Governors Bay and Diamond Harbour communities are predominantly residential and hence the wastewater is mostly household sewage and grey water. The wastewater discharged via the Lyttelton outfall is from the residential, the port and service areas of the township. Wastewater is, in particular, a source of nutrients, micro-organisms and freshwater to harbour water. There is potential for low concentrations of heavy metals and other chemicals to also be discharged.

Figure 3-5: Location of wastewater outfalls (green circles) and the closest water quality

sampling sites (blue circles)



3.2.1 Details of the discharge from each wastewater outfall Lyttelton (Sticking Point) outfall The maximum volume of wastewater allowed to be discharged from the Lyttelton outfall is 12,096 m3 per day. The actual volume discharged is variable (Figure 3-6) with elevated volumes during heavy rainfall. Elevated volumes during wet weather are due to stormwater entry from surface flooding, ground water infiltration, low gulley traps on private property and from illegal connections of stormwater pipes on private properties (M. Bourke, CCC, pers.com.). There are no consent requirements for the measurement of wastewater nutrient concentrations. Therefore, there are no data on the concentrations of nutrients and hence quantities of nutrients discharged via the Lyttelton outfall into harbour water.

Figure 3-6: Daily wastewater discharge volumes, Lyttelton outfall, January 2007-June 2008

Data provided by Christchurch City Council

Governors Bay outfall The maximum volume of effluent allowed to be discharged from the Governors Bay outfall is 600 m3 per day. The actual volume discharged is variable (Figure 3-7) with elevated volumes during heavy rainfall. Elevated volumes during wet weather are due to stormwater entry from surface flooding, ground water infiltration, low gulley traps on private property and from illegal connections of stormwater pipes on private properties (M. Bourke, CCC, pers.com.). The consent requires the measurement of DRP, NH3N and TN concentrations in the effluent before discharge. While there are no limits on the discharge concentration for any of these nutrients the measurements provide information on the quality of the effluent. Nutrient concentrations in the effluent are variable (Figure 3-8). Between January 2007 and June 2008 NH3N concentrations ranged from <1 – 18.2 mg/L, TN concentrations ranged from 2 – 23 mg/L and DRP concentrations ranged from 0.29 – 9.9 mg/L. The NH3N typically accounted for most of the nitrogen present.

0

500

1000

1500

2000

2500

3000

3500

1-Ja

n-07

15-J

an-0

729

-Jan

-07

12-F

eb-0

726

-Feb

-07

12-M

ar-0

726

-Mar

-07

9-Ap

r-07

23-A

pr-0

77-

May

-07

21-M

ay-0

74-

Jun-

0718

-Jun

-07

2-Ju

l-07

16-J

ul-0

730

-Jul

-07

13-A

ug-0

727

-Aug

-07

10-S

ep-0

724

-Sep

-07

8-O

ct-0

722

-Oct

-07

5-N

ov-0

719

-Nov

-07

3-D

ec-0

717

-Dec

-07

31-D

ec-0

714

-Jan

-08

28-J

an-0

811

-Feb

-08

25-F

eb-0

810

-Mar

-08

24-M

ar-0

87-

Apr-

0821

-Apr

-08

5-M

ay-0

819

-May

-08

2-Ju

n-08

16-J

un-0

830

-Jun

-08

Dis

char

ge v

olum

e (m

3 /day

)



Figure 3-7: Daily wastewater discharge volumes, Governors Bay outfall, January 2007-June

2008 Data provided by Christchurch City Council

Figure 3-8: Nutrient concentrations (mg/L) in effluent discharged from the Governors Bay outfall, January 2007- June 2008 Data provided by Christchurch City Council

0

50

100

150

200

250

300

350

400

450

500

1-Ja

n-07

15-J

an-0

729

-Jan

-07

12-F

eb-0

726

-Feb

-07

12-M

ar-0

726

-Mar

-07

9-Ap

r-07

23-A

pr-0

77-

May

-07

21-M

ay-0

74-

Jun-

0718

-Jun

-07

2-Ju

l-07

16-J

ul-0

730

-Jul

-07

13-A

ug-0

727

-Aug

-07

10-S

ep-0

724

-Sep

-07

8-O

ct-0

722

-Oct

-07

5-N

ov-0

719

-Nov

-07

3-D

ec-0

717

-Dec

-07

31-D

ec-0

714

-Jan

-08

28-J

an-0

811

-Feb

-08

25-F

eb-0

810

-Mar

-08

24-M

ar-0

87-

Apr-

0821

-Apr

-08

5-M

ay-0

819

-May

-08

2-Ju

n-08

16-J

un-0

830

-Jun

-08

Dis

char

ge v

olum

e (m

3 /day

)

0

5

10

15

20

25

30

Jan-

07

Mar

-07

May

-07

Jul-0

7

Sep

-07

Nov

-07

Jan-

08

Mar

-08

May

-08

Month

Con

cent

ratio

n (m

g/L)

dissolved reactive phosphorustotal nitrogenammonia-nitrogen



Nutrient concentration data, collected since January 2005, in combination with effluent volume data were used to calculate the mass loads discharged into the harbour per day and per year (Table 3.3). The annual mass load was calculated using both the mean and median daily mass load values. These calculated mass loads are a best a crude estimate of the annual loads discharged into the harbour because they are based on 46 data points. The total weight of each nutrient discharged into the harbour is variable as a consequence of the variation in both effluent nutrient concentration and volume discharged per day.

Table 3.2: Mass loads of ammonia nitrogen, total nitrogen and dissolved reactive phosphorus discharged into the harbour from the Governors Bay outfall n = number of samples used in the calculations Calculated from data provided by Christchurch City Council

Diamond Harbour outfall (Pauaohinekotou Heads) The maximum volume of effluent allowed to be discharged from the Diamond Harbour outfall is 2500 m3 per day. The actual volume discharged is variable (Figure 3-9) with elevated volumes during heavy rainfall. Elevated volumes during wet weather are due to stormwater entry from surface flooding, ground water infiltration, low gulley traps on private property and from illegal connections of stormwater pipes on private properties (M. Bourke, CCC, pers.com.). The consent requires the measurement of DRP, NH3N and TN concentrations in the effluent before discharge. While there are no limits on the discharge concentration for any of these nutrients the measurements provide information on the quality of the effluent. Between January 2007 and June 2008 NH3N concentrations ranged from <0.5 - 12 g/m3. TN concentration ranged from 1 - 28 g/m3 and DRP concentrations ranged from 3.3 - 9.3 g/m3 (Figure 3-10). The NH3N did not typically account for most of the nitrogen present, that is, oxidised and/or organic nitrogen are present in the effluent. The nutrient concentration data collected since January 2005 in combination with effluent volume data were used to calculate the mass loads discharged into the harbour (Table 3-3). The annual mass load was calculated using both the mean and median daily mass load values. These calculated mass loads are a best a crude estimate of the annual loads discharged into the harbour because they are based on 43 data points. The total weight of each nutrient discharged into the harbour is variable as a consequence of the variation in both effluent nutrient concentration and volume discharged per day.

NH3N kg/day TN kg/day DRP kg/day

Minimum 0.06 0.26 0.03

Median 1.08 1.53 0.45

Mean 1.39 1.98 0.51

SD 1.41 1.46 0.36

Maximum 5.80 6.35 1.45

n 46 46 46

NH3N kg/year TN kg/year DRP kg/year

Median 394.02 557.39 163.72Mean 508.71 723.22 187.57



Figure 3-9: Daily wastewater discharge volumes, Diamond Harbour outfall, January 2007-

June 2008 Data provided by Christchurch City Council

Figure 3-10: Nutrient concentrations (mg/L) in effluent discharged from the Diamond Harbour outfall, January 2007- June 2008 Data provided by Christchurch City Council

0

200

400

600

800

1000

12001-

Jan-

0715

-Jan

-07

29-J

an-0

712

-Feb

-07

26-F

eb-0

712

-Mar

-07

26-M

ar-0

79-

Apr-

0723

-Apr

-07

7-M

ay-0

721

-May

-07

4-Ju

n-07

18-J

un-0

72-

Jul-0

716

-Jul

-07

30-J

ul-0

713

-Aug

-07

27-A

ug-0

710

-Sep

-07

24-S

ep-0

78-

Oct

-07

22-O

ct-0

75-

Nov

-07

19-N

ov-0

73-

Dec

-07

17-D

ec-0

731

-Dec

-07

14-J

an-0

828

-Jan

-08

11-F

eb-0

825

-Feb

-08

10-M

ar-0

824

-Mar

-08

7-Ap

r-08

21-A

pr-0

85-

May

-08

19-M

ay-0

82-

Jun-

0816

-Jun

-08

30-J

un-0

8

Dis

char

ge v

oum

e (m

3 /day

)

0

10

20

30

40

Jan-

07

Mar

-07

May

-07

Jul-0

7

Sep

-07

Nov

-07

Jan-

08

Mar

-08

May

-08

Month

Con

cent

ratio

n (m

g/L)

dissolved reactive phosphorustotal nitrogenammonia-nitrogen



Table 3.3: Mass loads of ammonia nitrogen, total nitrogen and dissolved reactive phosphorus discharged into the harbour from the Diamond Harbour outfall n = number of samples used in the calculations Calculated from data provided by Christchurch City Council

NH3N kg/day TN kg/day DRP kg/day

Minimum 0.02 0.22 0.32Median 0.27 2.18 1.17Mean 0.89 2.90 1.22SD 1.61 2.63 0.63Maximum 7.72 15.45 4.57n 43 43 43

NH3N kg/year TN kg/year DRP kg/yearMedian 100.12 794.24 425.59Mean 324.83 1059.43 445.08

3.2.2 Effluent mixing and distribution The discharged treated effluent will mix and circulate with harbour water through the tidal and wind driven circulation patterns and long-term equilibrium mixing processes that occur in this harbour (Spigel, 1993). Within the harbour water circulation is typically asymmetric and tidally driven; the water does not simply flow up and down the harbour. The tide appears to flood more strongly on the south side of the harbour and ebb more strongly on the north side (Garner and Ridgeway, 1955). Deduced, but not directly measured, are large scale tidal gyres that flow clockwise on the ebb tide and counter-clockwise on the flood tide in the outer half of the harbour (Curtis, 1985) (Figure 3-11). These gyres do not influence the water circulation patterns within the upper harbour (Curtis, 1985). Mixing of water in the upper harbour is more restricted and tidal ‘excursions’ are smaller than in the outer half of the harbour (Spigel, 1993). Mean tidal velocities of 0.15 ms-1 west of the port, up to 0.23 ms-1 in the central harbour, and up to 0.27 ms-1 near the harbour entrance have been reported (Curtis, 1985). These speeds equate to a distance travelled of 3.35 km west of the port, 5.03 km in the central harbour and 5.92 km near the harbour entrance in one half of an average tidal cycle (6.21 hours) (Spigel, 1993). The above information indicates that the direction of flow of an effluent plume and mixing of the discharged effluent will be variable. Dye release studies have been carried out to investigate the effluent plumes from the Lyttelton outfall (Spigel, 1993) and the Diamond Harbour outfall (MWH, 2003). Lyttelton outfall Vertical mixing was completed within 500 m to 1 km from the discharge point. Dye was detected along an east-west axis and up to 3.5 km west and 5 km east of the outfall. The dye mixed across the width of the entire harbour within two tidal cycles (1 day). The mixing patterns observed fitted with the tidal circulation patterns described above. Spigel (1993) determined that advection by tidal currents in combination with turbulent diffusion dominated the mixing of discharged effluent with sea water. Diamond Harbour outfall On an outgoing tide the dye dispersed to the east from the outfall. On an incoming tide the dye dispersed as a long narrow plume in a generally south-west direction towards the southern headland of Church Bay (Black Point). The mixing patterns observed fitted with the tidal circulation patterns described above. It was estimated in the worst case situation there would be 300 fold dilution of the effluent within 10 m of the surface point directly above the outfall.



Figure 3-11: Water circulation in Lyttelton Harbour/Whakaraupō (from Curtis, 1985)

3.2.3 Influence of wastewater discharges on harbour water quality Sewage is a known source of ammonia nitrogen (NH3N). To assess the influence of the discharged wastewater on harbour water quality, NH3N concentrations at all sampling sites were compared. Particular interest was paid to the results for Governors Bay, Quail-Rapaki, Church Bay, the inner port entrance and Ripapa-Battery which are in proximity to outfalls (Figures 3-5 and 3-12). Only the most recent data, i.e. 2002-2003 and 2007-2008 were used. The rationale being that wastewater discharge volumes would be higher in the 2000s than the early 1990s as a result of the increase in the human population around the harbour.



Figure 3-12: View of Church Bay and the Diamond Harbour wastewater treatment plant

Comparison of ammonia nitrogen concentrations between sites The minimum, median and maximum values at each site in 2002-2003 and 2007-2008 are given in Table 3.5 and shown in Figure 3-13.

Table 3.4: Summary of ammonia nitrogen concentrations at each site in 2002-2003 and 2007-2008

Church Bay

Diamond Harbour WTP

Cha

rter

is B

ay

Gov

erno

rs B

ay

Qua

il-R

apak

i

Cor

sair

Bay

Chu

rch

Bay

Inne

r Por

t en

tran

ce

Pura

u B

ay

Rip

apa

Rip

apa-

Bat

tery

Har

bour

en

tran

ce

Minimum < 0.005 < 0.005 < 0.005 < 0.005 < 0.005 < 0.005 < 0.005Median 0.007 0.008 0.009 0.005 0.0025 0.005 0.011Maximum 0.033 0.025 0.025 0.055 0.033 0.021 0.028

Minimum 0.029 0.021 0.020 0.025 0.026 0.032 0.031 0.023 0.015Median 0.045 0.038 0.045 0.043 0.046 0.059 0.046 0.043 0.045Maximum 0.093 0.054 0.12 0.091 0.1 0.1 0.06 0.088 0.064

2002-2003 (n = 11)

2007-2008 (n = 12)



Figure 3-13: Box and whisker plots of the ammonia nitrogen concentrations at each site in

A: 2002-2003

B: 2007-2008 horizontal bar = median , box = interquartile range, whisker ends = % and 95%iles = outlier values, = extreme values

A

B

Charte

Gove

Corsair B In

Purau Ba

Ripapa

Ha

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

NH

3N concentration (mg/L)

Charte

Gove

Quail-R

Corsair B

Church B In

Purau Ba

Ripap

Ha

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

NH

3N concentration (mg/L)



The summary data and the box and whisker plots indicate that: • in both time periods the NH3N concentrations at the Governors Bay site did not have the

largest range or highest median; • in 2002-2003 the highest median concentration was at the harbour entrance while the

highest maximum concentration was at the inner port entrance; • in 2007-2008 the highest median concentration was at the inner port entrance while the

maximum concentration at this site was higher than that at six sites; • in 2007-2008 the highest maximum concentration was at the Quail-Rapaki site.

The Wilcoxon two-tailed sign test was used to determine if, over 2002-2003 and 2007-2008, there was a significant difference in NH3N concentration between sites. This found:

• in 2002-2003 concentrations at the harbour entrance were significantly higher than at Ripapa; • in 2007-2008 concentrations at the inner port entrance were significantly higher than at all

other sites except Charteris Bay; • in 2007-2008 concentrations in Charteris Bay, Church Bay and Purau Bay were higher than in

Governors Bay. These results indicate that the wastewater outfalls are not a major contributor of NH3N to the Governors Bay, Quail-Rapaki, Church Bay and Ripapa-Battery sites such that the concentrations at these sites are notably higher than those at the other sampled sites. However, the occasional high NH3N concentration at these sites may result from diluted wastewater effluent. The NH3N concentrations at the inner port entrance could result from diluted wastewater effluent as well as other sources. Is there any detectable influence of the effluent from each outfall? The track of the effluent plume from each outfall is influenced by the water circulation patterns in the harbour, i.e. tide and wind. To assess the influence of the tide and wind, and hence discharged wastewater on NH3N concentrations at the Governors Bay, Quail-Rapaki, Church Bay, inner port entrance and Ripapa-Battery water quality sampling sites, NH3N concentrations were plotted against state of the tide and wind direction. The state of the tide was determined as either high, low, incoming (with the number of hours given) and outgoing (with the number of hours given). Governors Bay outfall Governors Bay site The water quality sampling site is 1,590 m SW of the wastewater outfall. The discharged wastewater will potentially influence NH3N concentrations at the site on an incoming tide and/or when there is a north-easterly to easterly wind. At a tidal velocity of 0.15 m/s it would theoretically take around 3 hours for the effluent plume to reach this site. Ammonia nitrogen concentrations on an incoming tide were not higher than those on an outgoing tide (Figure 3-14). In both 2002-2003 and 2007-2008 the highest NH3N concentrations occurred when the wind was north-easterly to easterly. However, there are insufficient data to conclude that these higher concentrations were caused by wind driven effluent from the Governors Bay outfall. More data are required to assess whether or not effluent from the Governors Bay outfall is having an influence on NH3N concentrations at this site.



Figure 3-14: The influence of state of the tide and wind direction at the time of sampling on ammonia nitrogen concentrations (mg/L) at the Governors Bay site

Quail-Rapaki site The Quail-Rapaki water quality sampling site is 790 m NE of the wastewater outfall. The discharged wastewater will potentially influence NH3N concentrations at this site on an outgoing tide and/or when there is a southerly to south westerly wind. At a tidal velocity of 0.15 m/s it would theoretically take 1½ hours for the effluent plume to reach this site. The highest NH3N concentration occurred on an incoming tide (Figure 3-15). Apart from this high value, some concentrations 1.25 hours or more into the outgoing tide were 0.005 – 0.01 mg/L higher than those on an incoming tide. These results suggest that effluent from the Governors Bay outfall may have an influence on NH3N concentrations at this site. However, more data are required to assess whether or not effluent from the Governors Bay outfall is resulting in higher NH3N concentrations at the Quail-Rapaki site on an outgoing than an incoming tide.

Figure 3-15: The influence of state of the tide and wind direction at the time of sampling on ammonia nitrogen concentrations (mg/L) at the Quail-Rapaki site

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

outg

oing

0.5

outg

oing

1ou

tgoi

ng 1

.25

outg

oing

1.5

outg

oing

2ou

tgoi

ng 2

.5ou

tgoi

ng 3

.5ou

tgoi

ng 4

.25

outg

oing

5ou

tgoi

ng 5

.5ou

tgoi

ng 5

.5 low

low

low

low

inco

min

g 1

inco

min

g 2.

5in

com

ing

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inco

min

g 3

inco

min

gin

com

ing

5.5

inco

min

g

State of the tide

NH

3N c

once

ntra

tion

(mg/

L)2002-2003

2007-2008

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 30 60 90 120 150 180 210 240 270 300 330 360

Wind direction (degrees)

NH

3N c

once

ntra

tion

(mg/

L)

2002-20032007-2008

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

outg

oing

5

outg

oing

4.2

5

outg

oing

1.7

5

outg

oing

1.5

outg

oing

1.2

5

outg

oing

0.7

5

outg

oing

0.5 low

inco

min

g 2.

5

inco

min

g 2.

5

inco

min

g 3

high

State of tide

Nh3

N c

once

ntra

tion

(mg/

L)

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0 30 60 90 120 150 180 210 240 270 300 330 360


NH

3N c

once

ntra

tion

(mg/

L)



The highest NH3N concentration was recorded when the wind was from the NE. Apart from this high concentration, the concentrations recorded during NE-E winds were similar to those during SW-W winds. More data are needed to assess whether or not wind direction has an influence on the dispersal of effluent from the Governors Bay outfall.

Diamond Harbour outfall

Church Bay site

The Church Bay water quality sampling site is 711 m SSW of the wastewater outfall. The discharged wastewater will potentially influence NH3N concentrations at the site on an incoming tide and/or when there is a NE to NW wind. At a tidal velocity of 0.15 m/s it would theoretically take 1½ hours for the effluent plume to reach this site.

The three highest NH3N concentrations occurred either on the incoming tide or at high tide (Figure 3-16). The wind was NE on the day the highest NH3N concentration was recorded in Church Bay. These results suggest that effluent from the Diamond Harbour outfall may influence NH3N concentrations at this site.

Figure 3-16: The influence of state of the tide and wind direction at the time of sampling on

ammonia nitrogen concentrations (mg/L) at the Church Bay site

Lyttelton outfall Inner port entrance site The inner port entrance water quality sampling site is 1530 m west of the wastewater outfall. The discharged wastewater will potentially influence NH3N concentrations at the site on an incoming tide and/or when there is a NE to easterly wind. At a tidal velocity of 0.23 m/s it would theoretically take about 2 hours for the effluent plume to reach this site. In 2002-2003 the highest NH3N concentration occurred when the tide had been incoming for three hours (Figure 3-17) and the wind was WNW. In 2007-2008 the highest concentrations occurred 1 hour into the incoming tide and the wind was E-NE. These results suggest that effluent from the Lyttelton outfall may influence NH3N concentrations at this site.

0

0.02

0.04

0.06

0.08

0.1

0.12

outg

oing

4.7

5

outg

oing

4

outg

oing

2 low

inco

min

g 2

inco

min

g 2.

25

inco

min

g 2.

5

inco

min

g 4.

25

high

high

high

hig

h

State of tide

NH

3N c

once

ntra

tion

(mg/

L)

0

0.02

0.04

0.06

0.08

0.1

0.12

0 30 60 90 120 150 180 210 240 270 300 330 360


NH

3N c

once

ntra

tion

(mg/

L)




ammonia nitrogen concentrations (mg/L) at the inner port entrance site

Ripapa-Battery site

The Ripapa-Battery water quality sampling site is 1080 m east of the wastewater outfall. The discharged wastewater will potentially influence NH3N concentrations at the site on an outgoing tide and/or when there is a SW to westerly wind. At a tidal velocity of 0.23 m/s it would theoretically take about 1½ hours for the effluent plume to reach this site. Ammonia-nitrogen concentrations on an outgoing tide were not higher than those on an incoming tide (Figure 3-18). The highest NH3N concentration occurred on an incoming tide and ENE wind. Two of the higher NH3N concentrations occurred when there was a westerly and NW wind. There are insufficient data to conclude that these higher concentrations are caused by wind driven effluent from the Lyttelton outfall. More data are required to assess whether or not effluent from the Lyttelton outfall is having an influence on NH3N concentrations at this site.


ammonia nitrogen concentrations (mg/L) at the Ripapa-Battery site

0

0.02

0.04

0.06

0.08

0.1

outg

oing

5

outg

oing

3.7

5

outg

oing

3

outg

oing

1

outg

oing

1

outg

oing

0.5

inco

min

g 1

inco

min

g 1

inco

min

g 1.

5

inco

min

g 4.

5

inco

min

g 5.

5

high

State of tide

NH

3N c

once

ntra

tion

(mg/

L)

0

0.02

0.04

0.06

0.08

0.1

0 30 60 90 120 150 180 210 240 270 300 330 360


NH

3N c

once

ntra

tion

(mg/

L)

0

0.02

0.04

0.06

0.08

0.1

0.12

outg

oing

5.5

outg

oing

5.2

5ou

tgoi

ng 5

outg

oing

4.7

5ou

tgoi

ng 4

.25

outg

oing

3.5

outg

oing

3.5

outg

oing

3.2

5ou

tgoi

ng 3

outg

oing

1.2

5ou

tgoi

ng 1

.25

outg

oing

1.2

5ou

tgoi

ng 0

.5 low

inco

min

g 0.

75in

com

ing

1in

com

ing

1in

com

ing

3in

com

ing

3.5

inco

min

g 4.

25in

com

ing

5hi

gh

State of tide

NH

3N c

once

ntra

tion

(mg/

L)

2002-20032007-2008

0

0.02

0.04

0.06

0.08

0.1

0.12

0 30 60 90 120 150 180 210 240 270 300 330 360


NH

3N c

once

ntra

tion

(mg/

L)

2002-20032007-2008



3.3 Discussion The streams and wastewater discharges as sources of freshwater and nutrients, influence harbour water salinity and nutrient concentrations. These influences are shown by the data presented in this chapter and are discussed below. In 2007 salinity at all sites was lowest in winter and early spring then increased in late spring to be highest in December. These differences in salinity are attributed to temporal differences in the volume of freshwater flowing into the harbour which result from temporal differences in rainfall. There was also between site differences in salinity. These differences are attributed to differences in the distance from, and number of, streams in proximity to, the harbour sites. The temporal and spatial differences in salinity indicate that rainfall and hence freshwater flows into the harbour have a considerable influence on harbour water. On one occasions salinity at the harbour entrance was lower than that at sites within the harbour. This suggests that the water at this site contained freshwater from a source outside of the harbour, with the Waimakariri River the most likely source. The streams are, in particular, a contributor of NNN, DRP and TP to harbour water. The volcanic rock of Banks Peninsula is phosphorus rich and a source of phosphorus to stream water and hence harbour water. This is highlighted by the comparison of median TP and DRP concentrations in Lyttelton Harbour/Whakaraupō streams to that in the Ashburton River. The median concentrations in the streams are about an order of magnitude higher than in the Ashburton River (Croucher, 2010). The evaluation of the influence of rainfall volume and hence stream flows on harbour water nutrient concentrations found that the highest concentrations of NNN appeared to result from very heavy rainfall, i.e. 50 mm prior to sampling. The harbour water concentrations of other nutrients at sites 320 m or more from a stream mouth were not found to be influenced by high rainfall volumes prior to sampling. Treated wastewater is discharged into Lyttelton Harbour/Whakaraupō via three outfalls. The maximum consented wastewater volume is 15 196 m3/day. As wastewater is a source of NH3N, TN and DRP to harbour water, the operator of two of the wastewater treatment plants is required to routinely measure the concentration of these nutrients in the discharge. There is currently no such requirement for the Lyttelton outfall. The NH3N, TN and DRP concentrations in the Governors Bay and Diamond Harbour wastewater are variable over time. The NH3N in the Governors Bay wastewater typically accounted for most of the nitrogen present, this was not the case for the Diamond Harbour wastewater. Most of the nitrogen in the Diamond Harbour wastewater exists as either NNN or organic nitrogen. Harbour water NH3N concentrations at sites closed to the outfalls were examined to assess the influence of discharged wastewater. NH3N concentrations at the sites closest to each wastewater discharge, i.e. 382 - 2300 m away were not notably higher than those at other harbour sites. However, wastewater entrained by tide and/or wind driven currents could account for the occasional higher ammonia-nitrogen concentrations at sites 382 – 1530 m from an outfall. It was not possible to compare the quantity of nutrients discharged into the harbour via wastewater discharges and the streams. Quantity is calculated using nutrient concentration and flow data collected on the same day. Flows and nutrient concentrations were recorded on the same day for the Governors Bay and Diamond Harbour wastewater discharges but no such data were available for the Lyttelton wastewater discharge. For the streams, nutrient concentrations were measured but stream flows were not. The annual mass load of NH3N, TN and DRP discharged into the harbour from the Governors Bay and Diamond Harbour wastewater outfalls was calculated. More NH3N is discharged into the harbour annually in the Diamond Harbour than the Governors Bay wastewater. However, more TN and DRP are discharged into the harbour annually in the Governors Bay than the Diamond Harbour wastewater. Based on mean loads per day, around 834 kg of NH3N, 1783 kg of TN and 633 kg of DRP are discharged into the harbour per year via the Diamond Harbour and Governors Bay outfalls. A potential impact of stream and outfall nutrient inputs on harbour water is enhanced aquatic plant, i.e. phytoplankton (plant plankton), and algae growth. In sea water the critical limiting nutrient for phytoplankton growth is considered to be dissolved inorganic nitrogen (DIN) (DIN = NNN+NH3N) (NRC, 2001). Although high DIN concentrations can lead to excessive phytoplankton growth (which can result in an algal bloom), the relative availability of nitrogen and phosphorus, the flushing, light regime, temperature and the availability of other chemicals such as silica and iron are also important (ANZECC, 2000; NRC, 2001). There is more likely to be enhanced aquatic plant growth as a



consequence of inputs of nutrients to harbour water in spring and summer rather than late autumn and winter. It is not possible to evaluate the relative influence of stream inputs and wastewater inputs on harbour water DIN concentrations in each of the seasons. However, the following is an outline of what likely happens based on the information gathered. Nutrients are discharged continuously through the year via the outfalls. The concentrations are variable as are wastewater flows, with elevated flows during heavy rainfall. Nutrient inputs via the streams depend on stream flows which are influenced by rainfall. Hence flows are typically lower in summer than in winter. The streams more than likely contribute more nutrients to harbour water over the winter than over the summer. Based on the above information it is estimated that in the wetter months the streams contribute more nutrients to harbour water than the discharged wastewater while in the drier months the discharged wastewater contributes more nutrients than do the streams. The implication of this is that when water temperature and light regimes are optimal for plant growth it is the nutrient inputs from outfalls that are more likely to cause excessive phytoplankton growth rather than inputs from the streams.



4 Total suspended solids concentrations in harbour water

Total suspended solids (TSS) include inorganic (non living) particles such as the sand and mud stirred up from the seabed and soil washed off the land, and organic (from living things) particles like detritus (dead plant or animal material) and live organisms. TSS concentrations in Lyttelton Harbour/Whakaraupō water will be influenced by water depth, wind speed, rainfall, land use within the catchments and distance from shore.

Figure 4-1: Aerial view of the upper harbour, January 2009. Head of the Bay in the foreground and Governors Bay and the northern shoreline are in the background. Pegasus Bay in the distance at the top of the picture

Photo supplied by Robyn Croucher, Environment Canterbury

4.1 Water depth and TSS concentrations The water depth at the time of sampling has the potential to influence the quantity of suspended solids in the water. In shallow water wind-driven waves can re-suspend seabed sediments into the water column. The depth of such influence is dependent on the strength of the wind. In addition at shallow sites the re-suspended sediment will be present in the surface water, i.e. the water that was sampled. The deeper the water the less likely that seabed sediments will be re-suspended by wind forcing and the less likely re-suspended sediment will be in the surface water.



4.1.1 Water depths at the sampling sites A summary of the water depths (calculated) at the time of sampling, at sampling sites, is given in Table 4.1.

Table 4.1: Summary of water depth (m) at the time of sampling

Cha

rter

is B

ay

Gov

erno

rs B

ay

Qua

il-R

apak

i

Cor

sair

Bay

Chu

rch

Bay

inne

r por

t en

tran

ce

Pura

u B

ay

Rip

apa

Rip

apa-

Bat

tery

Har

bour

ent

ranc

e

Minimum 1.0 0.3 1.0 12.0 2.3 8.6 13.3Median 2.2 1.4 1.9 12.8 3.4 9.7 14.0Maximum 2.7 2.0 2.8 13.7 3.9 10.1 14.6Minimum 1.2 0.5 1.2 12.0 2.4 8.7 13.2Median 2.4 1.7 2.4 13.5 3.5 9.8 14.1Maximum 2.8 2.2 2.9 13.9 4.0 10.3 14.8Minimum 0.9 0.2 1.4 12.0 2.1 8.4 13.0Median 1.4 0.7 2.0 12.6 2.6 9.0 13.5Maximum 2.8 2.1 3.3 13.9 4.0 10.3 14.9Minimum 1.1 0.4 2.5 1.6 1.1 12.1 2.4 11.1 13.2Median 2.0 1.4 3.5 2.5 2.0 13.3 3.4 12.1 14.3Maximum 3.0 2.3 4.3 3.4 3.0 13.9 4.2 12.8 14.9

1992-1993

1993-1994

2002-2003

2007-2008

4.1.2 Total suspended solids concentrations Total suspended solids (TSS) concentrations were only measured in 2007-2008. On each sampling occasion one TSS measurement was recorded from each site. A summary of TSS concentrations at sampling sites is given in Appendix 4 and shown in Figure 2-8.

4.1.3 Total suspended solids and water depth The highest TSS concentrations occurred at the shallowest site with a general decrease in concentration with increasing water depth (Figure 4-2). The range in TSS concentrations also decreased with increasing water depth. At the shallowest site the range in TSS concentrations was 6.1 – 100 mg/L while at the deepest site it was 3.5 - 14 mg/L.



Figure 4-2: Surface water total suspended solids concentrations (mg/L) in relation to water

depth

4.1.4 Seabed sediments at sites shallower than 5 metres At shallow sites seabed sediments are re-suspended by wind-driven wave action. The effect of this wave action will in part be influenced by the size of the particles that make up the seabed; the finer the particles the less wave energy required for re-suspension. The finer particles also remain suspended in the water column for longer than coarser particles, i.e. the coarser sand particles quickly settle to the seabed while finer clay particles remain suspended in water for a considerable period of time. The seabed sediments of the upper harbour were mapped in 2008 (Hart et al, 2008). The sediment grain size results for the sites closest to the water quality sampling sites are presented in Table 4.2.

Table 4.2: Percentage composition of the seabed sediment

Gravel Sand Silt Clay

64 - 2 mm 2000 - 0.063 µm 0.063 - 0.0036 µm <0.0036 µmCharteris Bay 0.11 10.08 75.31 14.5

Governors Bay 4.16 68.69 27.15

1.64 32.88 48.6 16.88

2.68 59.12 38.2

Corsair Bay 1.87 59.97 38.16

Church Bay 27.35 29.21 28.01 15.43

Purau Bay 0.2 53.53 39.55 6.73

Quail-Rapaki

0

20

40

60

80

100

120

0 2 4 6 8 10 12 14 16

Water depth (m)

TSS

conc

entr

atio

n (m

g/L)



The Quail-Rapaki site was about midway between two sites with different seabed grain size distributions hence the results for both sites are given. The seabed sediment at this site could either be similar to that at one or other of the sites or somewhere in between, i.e. 18% sand, 54% silt and 28% clay. The seabed sediment in proximity to: - the Charteris Bay, Governors Bay and Corsair Bay sites was predominantly silt-clay; - the Quail-Rapaki site was slightly more sandy that that at the above three sites; - the Church Bay site was a mix of gravel sand and silt; - the Purau Bay site was silty sand.

4.2 Factors influencing total suspended solids concentrations Total suspended solids concentrations at five sites - Charteris Bay, Governors Bay and Quail-Rapaki and to a lesser extent Corsair Bay and Church Bay, differed between sampling occasions (Figure 4-3). In particular there were peaks in TSS concentration at one or more sites on a number of occasions.

0

20

40

60

80

100

120

1-Ju

l-07

15-J

ul-0

7

29-J

ul-0

7

12-A

ug-0

7

26-A

ug-0

7

9-S

ep-0

7

23-S

ep-0

7

7-O

ct-0

7

21-O

ct-0

7

4-N

ov-0

7

18-N

ov-0

7

2-D

ec-0

7

16-D

ec-0

7

30-D

ec-0

7

13-J

an-0

8

27-J

an-0

8

10-F

eb-0

8

24-F

eb-0

8

9-M

ar-0

8

23-M

ar-0

8

6-A

pr-0

8

20-A

pr-0

8

4-M

ay-0

8

18-M

ay-0

8

1-Ju

n-08

15-J

un-0

8

Date

Tota

l sus

pend

ed s

olid

s (m

g/L)

Charteris BayGovernors BayQuail-RapakiCorsair BayChurch BayInner port entrance Purau BayRipapa-Battery Harbour entrance

Figure 4-3: Total suspended solids concentrations (mg/L) at harbour sites in 2007-2008

To investigate the factors that may account for the peaks in TSS concentrations at these five sites TSS concentrations, total daily rainfall, maximum wind speeds and water depths were tabulated (Appendix 11). These data were examined in combination with the seabed sediment grain size data to determine the likely cause/s for the peaks in TSS concentration (Table 4.4). The results indicate that soil erosion with rainfall and/or re-suspension of fine seabed sediments as a result of shallow water in combination with wind typically account for elevated TSS concentrations. It is difficult to separate out the effects of rainfall and seabed re-suspension because rainfall is typically accompanied by moderate to high winds. The actual impact of any particular weather event on the TSS concentration varied between sites. That is, water depth, wind speed and direction, rainfall volume, distance from shore, and likely water circulation patterns all have a part to play.



Soil erosion as a result of 10.5 mm of rain on the day prior to sampling, in combination with re-suspension of seabed sediments by winds of up to 15.44 m/s on the day prior to, and winds of 5-6 m/s on the day of, sampling likely accounts for TSS concentrations of 100 mg/L at Governors Bay and 88 mg/L at Charteris Bay on 23 January 2008. There are two possible explanations for the higher concentration at Governors Bay than at Charteris Bay.

1. There were more re-suspended seabed sediments in the water at the Governors Bay than the Charteris Bay site. At both sites the seabed sediments are predominantly silt clay and would be easily re-suspended by wave action. However, the water depth at the time of sampling was 0.39 m at Governors Bay and 1.11 m at Charteris Bay and hence the wind could have re-suspended more seabed sediment at the Governors Bay than the Charteris Bay site.

2. The Governors Bay site was 325 m from land and 710 m from the closest stream (Zephyr Stream) while the Charteris Bay site was 880 m from land and 1035 m from the closest stream (an ephemeral stream). That is, soil erosion as a result of the rainfall on the day prior to sampling would dilute with distance from the source and thus be more diluted at Charteris Bay than Governors Bay.

Table 4.3: Summary of possible explanations for the total suspended solids concentrations of > 20 mg/L at five sites

TSS (mg/L) Possible explanation

88 Rainfall of 10. 5 mm and max. wind speed of 15.44 m/s 1 day prior to sampling, Water depth 1.11 m

46 Rainfall of 12.5 mm 2 days prior and 10 mm 1 day prior to sampling

27 Rainfall of 7.5 mm in hours prior to sampling, max. wind speeds of > 10m/s in the three days prior to sampling

27 indeterminate

100 Rainfall of 10. 5 mm and max. wind speed of 15.44 m/s 1 day prior to sampling, water depth 0.39 m

42Rainfall of 7.5 mm in hours prior to sampling, max. wind speeds of > 10m/s in the three days prior to sampling, water depth of 1.01 m

37 indeterminate

34 wind speeds of > 10m/s in the two days prior to sampling


21 Rainfall of 14 mm 1 day prior to sampling, max wind speed of > 10m/s two days prior to sampling

20 Water depth of 0.96 m

67 Rainfall of 10. 5 mm and max. wind speed of 15.44 m/s 1 day prior to sampling

20 indeterminate

20 indeterminate


26 indeterminate

23 Maximum wind speed of > 10 one day prior to sampling


38 Water depth of 1.33 m




20 Maximum wind speed of > 10 one day prior to sampling

Charteris Bay

Governors Bay

Quail-Rapaki

Church Bay

Corsair Bay

At the Quail-Rapaki site soil from rainfall runoff rather than re-suspension of seabed sediments likely accounts for the elevated TSS concentration on 23 January 2008 (Figure 4-3, Table 4.4). This assessment takes into account the fact that on this day the TSS concentration at the shallower Corsair Bay site was not high. There was a large difference in TSS concentrations between Charteris Bay and Corsair Bay even though the seabed at both sites is silt-clay and water depths are similar. This indicates that other environmental factors likely explain the difference in concentrations between these sites (Table 4.4).



One possible explanation is that more soil is transported into Charteris Bay than into Corsair Bay as a result of rainfall. This explanation is supported by the following catchment information. The largest stream flowing into Charteris Bay has a catchment area of 1063 ha of which 42.4 ha is active erosion scar. The stream flowing into Corsair Bay has a catchment area of 61 ha of which 5 ha is active erosion scar. In addition, depending on wind direction, the length of the fetch and its effect on the height of the wind-driven waves could result in differences in the depth of the disturbance and hence re-suspension of seabed sediment between sites.

4.3 Increase in suspended solids concentrations Each of the sites had TSS concentrations of <15 mg/L on many sampling occasions (Figure 4-3) which suggests that these could be ‘background’ or ‘typical’ concentrations. This assumption led to the question ‘Is it possible to determine by how much TSS concentrations at the five sites increases as a result of soil erosion and/or re-suspension of seabed sediments?’ To this end the mean of the six lowest values from a site was used as the ‘background’ concentration for the site. These ‘background’ concentrations were 10 mg/L in Charteris Bay, 13 mg/L in Governors Bay, 11.5 mg/L at Quail-Rapaki, 11.5 mg/L in Corsair Bay and 11.6 mg/L in Church Bay. The six higher values at a site were then divided by the mean to give the relative increase in TSS concentrations likely as a result of soil runoff and/or re-suspension of seabed sediment (Table 4.4).

Table 4.4: Relative increases in total suspended solids concentrations at the shallower sites

Site Relative increase in TSS concentration

Charteris Bay 1.7 - 8.8

Governors Bay 1.6 - 7.7

Quail-Rapaki 1.3 - 5.8

Corsair Bay 1.3 - 3.7Church Bay 1.3 - 3.3

There was a difference in the highest relative increase in TSS concentrations between sites. Of particular note is the difference in the highest relative increase between the Charteris Bay and Corsair Bay sites. The possible reasons for the difference between these sites are outlined above.

4.4 Total suspended solids concentrations following heavy rainfall

On 31 July 2008 24 mm and on 1 August 2008 21.5 mm of rain (prior to sampling) were recorded at Coopers Knob. This rainfall resulted in the transport of soil-laden fresh water into Hayes Bay (south of Church Bay) from a sediment retention pond and an ephemeral stream. The sediment retention pond was constructed to deal with sediment runoff from the large areas of bare soil created during the development phase for a subdivision, while road works were underway in the catchment of the ephemeral stream. As a consequence of soil runoff into the bay total suspended solids concentrations were measured at a number of sites within Hayes Bay and at the routine sites in Church Bay (210 m from shore) and Charteris Bay (900 m from shore) on the afternoon of 1 August 2008. The TSS concentration at Church Bay (87 mg/L) was more than twice the maximum recorded during routine sampling. The concentration at Charteris Bay (99 mg/L) was slightly higher than the maximum recorded during routine sampling. In Hayes Bay the TSS concentrations 22-29 m from shore ranged from 120-200 mg/L and concentrations 91-125 m from shore ranged from 74-84 mg/L.



These results indicate that:

1. soil laden freshwater flows into the harbour can result in high suspended solids concentrations in sea water to at least 29 m from shore.

2. TSS concentrations in Hayes Bay reduced with distance from shore. This would be through either dilution of the particles or settling of the particles to the seabed or a combination of both.

3. elevated TSS concentrations do occur at the Charteris Bay and Church Bay sites as a result of heavy rainfall.

4. re-suspension of seabed sediment at the Charteris Bay site could account for the higher concentration 900 m from land than at the Church Bay site 210 m from land.

4.5 Other influences on TSS concentrations To maintain the water at depths necessary for the large vessels that frequent the Port of Lyttelton there is ongoing maintenance dredging within the inner port and along an approximately 7 km long approach channel in the harbour. Two of the Environment Canterbury sampling sites, i.e. inner port entrance and Ripapa-Battery are within or in close proximity to the dredging area. The sediment that is dredged is deposited in spoil grounds on the outer eastern side of harbour between Battery Point and Godley Head. The dredging and deposition of seabed sediment will influence TSS concentrations through the water column in and adjacent to the area of activity. When dredging is underway there will be disturbance and hence re-suspension of seabed sediment along with some release of sediment from the dredge as it is raised to the sea surface to be deposited on a barge. TSS concentrations will typically be higher at the seabed and decrease with increasing distance from the seabed. Even so, discoloured water is visible at the sea surface when dredging is underway. Total suspended solids concentrations at the inner port entrance and Ripapa-Battery sites could be higher than that at other sites within the harbour when maintenance dredging is underway. There was no report that the dredge was operating in proximity to either of these sites when water quality sampling was being undertaken. 4.6 Discussion The water in Lyttelton Harbour/Whakaraupō is typically discoloured by the presence of total suspended solids. Across all nine sites the TSS concentrations recorded over 2007-2008 ranged from 3.5 – 100 mg/L with median concentrations ranging from 8.35 – 20.5 mg/L. By comparison TSS concentrations recorded at eight sites through Akaroa Harbour over 2008-2009 (Environment Canterbury data) ranged from 1.8 – 19 mg/L and median concentrations ranged from 7.2 – 10 mg/L. The predominant sources of total suspended solids to Lyttelton Harbour/Whakaraupō water are soil/sediment inputs from the land and natural and human induced re-suspended seabed sediment. The soil/sediment inputs from land are influenced by rainfall while the natural re-suspension of seabed sediment is influenced by water depth and wind speed. In shallow water wind driven waves re-suspend seabed sediments into the water column. The deeper the water the less likely that seabed sediments will be re-suspended by wind forcing and the less likely re-suspended sediment will be in surface water. It was found that TSS concentrations in Lyttelton Harbour/Whakaraupō water were higher at the shallower than the deeper sites with a decrease in concentration with increasing water depth. At the five upper harbour and hence shallower sites soil/sediment runoff with rainfall and/or re-suspension of fine seabed sediments as a result of shallow water in combination with wind typically accounted for elevated TSS concentrations. It is difficult to separate out the effects of rainfall and seabed re-suspension as rainfall is typically accompanied by moderate to high winds. However, the large difference in TSS concentrations between two sites with similar seabed sediment and of comparable depth, i.e. Charteris Bay and Corsair Bay, may have been due to more soil/sediment runoff with rainfall into Charteris Bay than into Corsair Bay. This is a plausible explanation because the



largest stream flowing into Charteris Bay has a catchment area of 1063 ha while the stream flowing into Corsair Bay has a catchment area of 61 ha. During a rainfall event that resulted in a notable input of soil/sediment to harbour water it was found that soil-laden freshwater inputs resulted in total suspended solids concentrations of 200 mg/L to at least 29 m, and 86 mg/L to at least 210 m, from shore. These results show that discharged soil/sediment affects harbour water TSS concentrations in proximity to, with a decrease in concentrations with increasing distance from, the soil/sediment source. Total suspended solids concentrations decrease with distance from the source through dilution and flocculation of particles followed by the settling to the seabed. The input of soil is an ongoing and major ecological issue for this harbour.



5 Microbiological water quality

5.1 Introduction Faecal matter from humans, other mammals and birds is a source of micro-organisms to harbour sea water. Once in the water these micro-organisms have the potential to contaminate shellfish and affect recreational users of the harbour. The filter-feeding shellfish ingest micro-organisms that can then accumulate in shellfish tissue. When this shellfish tissue is consumed it can cause gastro-intestinal upsets or worse. There are cockle and pipi beds, mussels and rock oysters within Lyttelton Harbour/Whakaraupō. These shellfish are collected for human consumption by recreational gatherers and for traditional occasions. Many of the bays around the harbour have a sandy beach beyond which is a gently sloping seabed, and are sheltered from the prevailing wind. As such they are popular swimming sites over the summer months. Sailing, water skiing, boating and kayaking are common summertime activities in the harbour. There are a variety of potential effects on recreational users when they ingest or are even immersed in sea water containing elevated concentrations of micro-organisms. There are three commonly used faecal indicator organisms. Escherichia coli (E. coli) is the indicator organism for freshwater, Enterococci is the indicator organism for sea water and faecal coliforms are a generic indicator organism. Faecal indicator organism concentrations in water provide an indication of the potential for the presence and abundance of faecal derived pathogens such as viruses and bacteria. Viruses that can be present in faecal matter include enterovirus which causes gastro-intestinal upset and adenovirus which causes respiratory illness. Bacteria that can be present in faecal matter include Campylobacter, Salmonella and Cryptosporidium.

5.2 Sources of micro-organisms to harbour water

5.2.1 Wastewater discharges The wastewater discharged into the harbour via three outfalls is treated prior to discharge. This treatment reduces but does not destroy all micro-organisms within the effluent. The discharged effluent is a potential source of micro-organisms to harbour water. The concentrations of faecal indicator organisms in the effluent (typically measured monthly) from the treatment plants have been monitored for a number of years. The data collected since January 2005 by the Christchurch City Council have been summarised and analysed; the results are provided in Table 5.1. The concentration of faecal indicator organisms in each of the wastewater discharges is highly variable. The median enterococci concentrations per 100 mL of effluent from the Governors Bay and Diamond Harbour outfalls were low. Eighty percent of the Governors Bay effluent samples contained less than 140 enterococci/100mL while 83% of the Diamond Harbour effluent samples contained less than 140 enterococci/100mL. Nonetheless tens of millions of enterococci are typically discharged into the harbour per day from these outfalls. For faecal coliforms the median concentration per 100mL of effluent differed between outfalls with the highest median concentration in Lyttelton effluent. Sixty percent of the Lyttelton effluent samples contained more than 43 faecal coliforms/100mL, while 43% of the Governors Bay effluent samples and 40% of the Diamond Harbour effluent samples contained more than 43 faecal coliforms/100mL. However, the maximum faecal coliform concentration per 100mL of effluent was more than an order of magnitude higher in the Governors Bay and Diamond Harbour effluent than the Lyttelton effluent. Typically tens of millions of faecal coliform bacteria are discharged into the harbour per day from these outfalls.



Table 5.1: Faecal indicator organism concentrations in each wastewater discharge n = number of samples

5.2.2 Waterways Faecal contamination of waterways is caused by direct faecal inputs from feral animals, birds and stock or from land runoff and stormwater during rainfall. Concentrations of the freshwater faecal indicator organism E. coli in six Lyttelton Harbour/Whakaraupō waterways were measured on ten occasions between September 2007 and December 2008. E. coli concentration in each waterway was variable (Table 5.2). The highest concentration, in all waterways except Rapaki Stream, occurred on 17 December 2008 and followed 10 mm of rainfall between midnight and 6 am on that day. The highest E. coli concentration occurred in Living Springs Creek. Environment Canterbury investigations of faecal contamination sources to Rapaki and Zephyr streams found that concentrations of faecal indicator organisms are influenced by rainfall, i.e. concentrations were higher following rainfall than during fine weather. The source of the faecal contamination to both streams was determined to be land runoff and urban stormwater. The E. coli concentrations indicate faecal contamination of all the waterways. Investigations into the faecal sources to Living Springs Creek, Teddington Stream, Te Wharau Stream and Purau Stream are recommended.

5.2.3 Stormwater There are no records of faecal indicator organism concentrations in the stormwater flowing into the waterways and directly into Lyttelton Harbour/Whakaraupō. However, as mentioned in the section above, concentrations of faecal indicator organisms in Zephyr and Rapaki streams are increased by stormwater inputs. There are insufficient data to quantify the increase resulting from stormwater input.

Lyttelton outfall Diamond Harbour Outfall Governors Bay outfall

Minimum 2 1 <1

Median 64 10 36

Mean 553 2461 4233

SD 1400 8776 19493

Maximum 8500 65000 150000

n 71 77 80

Minimum < 1 <1

Median <10 10

Mean 700 660

SD 2133 1870

Maximum 11000 10000n 42 43

Faecal coliforms (CFU/100mL)

Enterococci (CFU/100mL)

No

data



Table 5.2: E. coli concentrations (MPN/100mL) in six harbour streams/creeks

Dat

e

Rap

aki S

trea

m

Zeph

yr S

trea

m

Livi

ng S

prin

gs C

reek

Tedd

ingt

on S

trea

m

Te W

hara

u St

ream

Pura

u St

ream

27-Sep-07 690 1400 550 19

19-Dec-07 1700 820 770 610 770

6-Mar-08 180 33 2000 1000 230

26-Jun-08 23 15 650 690 140 42

21-Jul-08 64 33 690 1000 330 120

20-Aug-08 460 42 370 690 160 230

19-Sep-08 220 55 >2400 1700 730 77

21-Oct-08 1300 36 2400 690 230 130

18-Nov-08 1300 64 >2400 2000 580 520

17-Dec-08 110 1300 >24000 2400 >2400 >2400

Median 340 42 1700 1000 565 180

5.2.4 Birds Seagull, shag, Canada geese and duck faeces are likely to be a significant source of micro-organisms to harbour water. Various international studies have measured faecal indicator organism concentrations in faecal deposits from these birds. Averaged E. coli concentrations of 1.4 x 107 per gram (wet weight) have been found in gull and duck faeces while in geese faeces E. coli concentrations of 2.9 x 106 per gram (wet weight) have been reported (Sheridan et al., 2003). It is important to note that the average weight of geese faecal matter is typically more than 15 times higher than that of gulls. Canada geese faeces have been found to contain 1x102 – 1x107 enterococci g–1 wet weight of faeces (mean of 7.3x105 enterococci/0.1g wet weight of faeces) (Middleton and Ambrose, 2005). Another study found that Canada geese eliminate 107 faecal coliforms per day (Hussong et al., 1979). It has been estimated that a faecal deposit from a gull can contain 1.77 x 108 faecal coliforms (Alderiso & DeLuca, 1999). It has also been established that water fowl defecate about every three hours (Grant et al., 2001). These birds deposit faeces into water or onto intertidal sediment. It has been found that bird faeces on sediment are a significant contributor of enterococci to the water column even if the faeces have dried (Grant et al., 2001). Micro-organisms deposited on sediment can be dislodged and become suspended in the water column through tidal and wind driven water disturbance and other disturbances (such as trampling by birds and humans). Wave activity is critical in maintaining micro-organisms in suspension once in the water column. There are no available records on gull, shag, geese and duck numbers for Lyttelton Harbour/Whakaraupō and its catchments.



5.3 Concentrations of faecal indicator organisms in harbour water

5.3.1 In proximity to wastewater outfalls Governors Bay Faecal coliform and enterococci concentrations are measured 10 to 20 metres due north, due south, due west and due east of the outfall. These micro-organisms are measured at least five times over a 30 day period with samples collected within one hour of low tide. These measurements are required by the conditions of the resource consent for this discharge. To assess the impact of discharged effluent on sea water micro-organism concentrations, effluent and receiving environment data collected on the same day were analysed (Appendix 12). Faecal coliform concentrations of up to 6200 cfu/100mL in the effluent did not result in elevated faecal coliform concentrations in surface sea water 10-20 m away from the outfall in any direction. Effluent enterococci concentrations of 170 cfu/100mL in the effluent did not result in elevated enterococci concentrations in surface sea water 10- 20 m away from the outfall in any direction. Diamond Harbour Faecal coliform and enterococci concentrations are measured at 50 metres due north, due south, due west and due east of the outfall. These micro-organisms are measured at least five times over a 30 day period. These measurements are required by the conditions of the resource consent for this discharge. To assess the impact of the discharge on sea water micro-organism concentrations, effluent and receiving environment data collected on the same day were analysed (Appendix 12). Faecal coliform concentrations of up to 21000 cfu/100mL in the effluent did not result in elevated faecal coliform concentrations in surface sea water 50 m away from the outfall in any direction. Effluent enterococci concentrations of 6500 cfu/100mL in the effluent did not result in elevated enterococci concentrations in surface sea water 50 m away from the outfall in any direction.

5.3.2 Swimming beaches The water at eight swimming sites around the harbour has been sampled weekly over each summer since 2001-2002 with 12-15 samples per site per year. The concentration of enterococci in each sample is measured. The yearly enterococci data have been assessed against a guideline concentration of 140 enterococci/100 mL (Figure 5-1). Enterococci concentrations above 140/100 mL are indicative of faecal contamination and are considered to be of public health significance (MfE/MoH 2003). If there are more than 140 enterococci/100 mL the site is immediately re-sampled to determine if there is a microbial water quality problem. As 12-15 samples were collected per site per year, one exceedence of 140/100mL represents an annual compliance of 91-95% of samples. One exceedence/site/year is likely a random event and at many sites the faecal contamination source cannot be pinpointed. Possible random faecal sources include birds, other mammals, stormwater and general runoff. Two or more exceedences/site/year equates to an annual compliance of less than 90% of samples. When less than 90% of samples comply over two or more years it is likely that there has been or is an ongoing source of faecal contamination. Such sources are typically stormwater and faecally contaminated waterways.



Figure 5-1: Percentage of samples containing less than 140 enterococci/100 mL

Random faecal contamination occurs in Church Bay and typically in Charteris Bay and Rapaki Bay. Enterococci concentrations at the other five sites suggest ongoing sources of faecal contamination. Analyses of the data collected annually and/or investigations have found that enterococci concentrations in Purau Bay, Governors Bay, Diamond Harbour Bay and Corsair Bay are affected by rainfall, i.e. land runoff and stormwater discharges. There are no obvious sources of the faecal contamination to Cass Bay. The enterococci data that are collected over each summer are used to calculate the suitability for recreation grade (SFRG) for each site. The grading is based on both the potential for faecal contamination from nearby sources and number of faecal indicator organisms present, and follows the national Microbiological Water Quality Guidelines (MfE/MoH, 2003). The two components that are integrated to produce the SFRG for a site are:

• Historic enterococci results (the ideal being 5 years of data), which provide a measure of the general water quality over an extended period of time.

• The Sanitary Inspection Category, which represents a measure of the susceptibility of a water body to faecal contamination.

There are five SFRG – Very good, good, fair, poor and very poor. The risk of becoming sick from water-based activities increases as the grading shifts from very good to very poor. The SFRG describes the general condition of a site and is used as a tool to inform the public of the potential health risk associated with undertaking water-based activities at a site. The grades for the eight Lyttelton Harbour/Whakaraupō sites over time are given in Appendix 13.

5.3.3 Water overlying shellfish To determine if shellfish are safe to eat, the concentrations of faecal coliforms in water overlying shellfish are used as a guide to their microbiological quality. For the shellfish to be safe to eat the median concentration of faecal coliforms should not exceed 14/100mL and the single sample concentration of 43/100mL should not be exceeded in more than 10% of the samples (MfE/MoH, 2003).

2001

-200

2

2002

-200

3

2003

-200

4

2004

-200

5

2005

-200

6

2006

-200

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2007

-200

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2008

-200

9

Corsair Bay

Cass Bay

Rapaki Bay

Governors Bay

Charteris Bay

Church Bay

Diamond Harbour Bay

Purau Bay

100

96-99

91-95

86-90

81-85

76-80

71-75

66-70

Key (%)



One water sample has been collected weekly from Rapaki over each summer since 2004-05 with 12-15 samples/site/year. The concentration of faecal coliforms in each sample was measured (Table 5.3). In 2004-2005, 2005-2006, 2006-2007 and 2008-2009 more than 10% of the samples had more than 43/100mL hence the shellfish would not have been safe to eat. The guideline values were met in 2007-2008.

Table 5.3: Faecal coliform concentrations (cfu/100mL) in Rapaki Bay water over the last five summers

2004-2005 2005-2006 2006-2007 2007-2008 2008-2009

2 24 5 2 796 12 <1 12 1138 98 10 6 12 2 <2 21 8026 10 8 <1 11 6 9 7 44 54 >200 4 <22 1 6 27 64

160 1 <1 2 <262 20 137 8 104 24 1 23 <252 16 70 62 5212 2 17 5 41 22 202 16 2

Median 4 12 9 10 4

No > 43 4 2 2 1 3Percent > 43 26.67 15 23 6.7 20

An investigation of the potential sources of faecal coliforms to Rapaki Bay sea water was undertaken in 2006-2007. The data collected indicated:

1. Rapaki Stream is a potential source of faecal coliforms. 2. faecal coliform concentrations in Rapaki Stream are influenced by rainfall. 3. re-suspended seabed sediment is a potential source of faecal coliforms.

Faecal coliform concentrations in Rapaki Bay are influenced by rainfall and wind-driven waves. General land runoff and stormwater were the likely sources of the faecal contamination to the Rapaki Stream.

5.4 Micro-organisms in shellfish flesh The testing of shellfish flesh to measure micro-organism concentrations is not undertaken on a regular basis. However, in June 2009 blue mussels from Godley Head (Livingstone Bay), Pile Bay, Kamautaurua (Shag Reef), North Quail Island and Taukahara (Figure 5-2) and pipis from Rapaki, were collected and tested for a variety of faecal indicator organisms. The results are presented in Table 5.4.



Figure 5-2: Location of shellfish collection sites

Table 5.4: Faecal indicator organism concentrations in blue mussel and pipi flesh from harbour sites

Site ShellfishE. coli

(MPN/100g)Faecal coliform

(MPN/100g)

Presumptive coliforms

(MPN/100g)Livingstone Bay blue mussels 20 20 490

Pile Bay blue mussels < 18 < 18 330

Kamautaurua (Shag Reef) blue mussels 270 270 2400

North Quail Island blue mussels 2200 5400 5400

Taukahara blue mussels 78 78 790

Rapaki Beach pipi 20 20 330 For shellfish to be suitable/safe for consumption the flesh E. coli concentration should not exceed 230/100g flesh. In June 2009 blue mussels from North Quail Island and Kamautaurua (Shag Reef) were not suitable/safe for consumption.



The ratio of presumptive coliforms to both faecal coliforms and E. coli concentrations provides an indication of the source of the faecal contamination. Concentrations that are similar, i.e with a ratio close to 1, indicate that the faecal contamination originates from a warm blooded animal, i.e. mammals and birds. Presumptive coliforms concentrations that are considerably higher than faecal coliforms and E. coli concentrations indicate diffuse sources of faecal contamination such as land runoff. The results indicate that warm blooded animals were a significant source of the faecal contamination of blue mussels from North Quail Island. The results from all other sites indicate the faecal contamination was primarily from diffuse sources.

5.5 Discussion The three wastewater outfalls and the streams are contributors of significant concentrations of faecal micro-organisms to harbour water. Seagull, shag, Canada geese and duck faeces are also likely to be a significant source of micro-organisms to harbour water. The number of individuals of these birds around the harbour is unknown. Stormwater is also a contributor of faecally derived micro-organisms to harbour water. The wastewater discharged into the harbour via the three outfalls is treated to reduce the concentration of micro-organisms prior to discharge. This treatment reduces but does not destroy all micro-organisms, hence there are faecal indicator bacteria, viruses and pathogens in the wastewater discharged into harbour water. The discharged wastewater has a localised impact on microbiological water quality. On discharge the wastewater mixes with, and is diluted by, sea water such that faecal indicator bacteria concentrations at the edge of the mixing zone are typically low. This is evidenced by faecal coliform concentrations of typically <10 cfu/100mL, 20 m from the Governors Bay outfall and 50 m from the Diamond Harbour outfall. However, no detailed investigation has been carried out to the exact extent of the impact of a wastewater discharge on micro-organism concentrations. The impact of stream/creek water and stormwater discharges on harbour water faecal indicator bacteria concentrations will also be localised. Bacteria concentrations should decrease with increasing distance away from the mouth of the stream/creek or stormwater outlet. However, no data have been collected to determine the exact extent of each stream/creek and stormwater outlet on harbour water quality. Harbour water concentrations of the faecal indicator bacteria enterococci and faecal coliforms have been measured by Environment Canterbury as part of swimming water quality and shellfish safe to eat water quality. The results show that faecal indicator organism concentrations at the water edge were spatially and temporally variable with elevated concentrations at times. In particular faecal indicator bacteria concentrations at sites in Rapaki, Purau Bay, Governors Bay, Diamond Harbour Bay and Corsair Bay have been elevated at times. The potential sources of the faecal derived micro-organisms to these sites include stream water, stirred up seabed sediment and runoff from land. Testing of the flesh of shellfish living in the mudflats (pipis) and on shoreline rocks (blue mussels) indicate that the faecal derived micro-organisms mostly originate from diffuse sources such as land runoff and stream flows. However, the source of elevated faecal indicator bacteria in the blue mussels from North Quail Island was likely mammals and birds.



6 Overall assessment of harbour water quality

6.1 Water quality for ecological health This is an assessment of the ecological health of Lyttelton Harbour/Whakaraupō based on the following water quality parameters:

• oxygen concentrations • nutrient concentrations • chlorophyll-a concentrations • total suspended solids concentrations

6.1.1 Oxygen concentrations The primary source of dissolved oxygen (DO) in surface water is oxygen from the atmosphere. The release of oxygen by phytoplankton and seaweeds is another DO source. Micro-organisms and animals living in the water column and in and on the seabed use oxygen and require sufficient DO to function normally. Hence, there are guideline trigger values for DO %saturation in estuarine and marine water (ANZECC, 2000) for the protection of marine life. The South-east Australia DO %saturation lower limit trigger values are 80 and 90 for estuaries and marine respectively. The upper limit trigger value is 110 for both environments. DO was measured at sites in Lyttelton Harbour/Whakaraupō in 2007-2008 (Figure 6-1). The DO %saturation ranged from 85 to 108 with 30% of samples having a %saturation of less than 90. Saturations of less than 90%:

1. occurred at sites in the summer months. 2. did not occur at the harbour entrance. 3. occurred more frequently at upper harbour than outer harbour sites (45% of samples at

Governors Bay and Quail-Rapaki, 36% at Church Bay and the inner port entrance, 27% in Charteris Bay and 18% at Corsair Bay, Purau Bay and Ripapa-Battery).

DO %saturation is influenced by water temperature with colder water having higher %saturation than warmer water (Appendix 14). DO %saturation below the 90% guideline trigger value typically occurred over the summer months. That is, the lower concentrations are likely more a function of water temperature rather than oxygen depletion by micro-organisms and animals. The DO %saturation at sites was at most 5% lower than the guideline trigger value for marine water, but was 5% higher than the trigger value for estuarine water. It is uncertain whether there is potential for the ecological health of the harbour to be affected by below the marine trigger values.

6.1.2 Nutrient concentrations Ammonia toxicity Ammonia is a non-persistent and non-cumulative toxicant to aquatic life (ANZECC, 2000). Ammonia nitrogen can be toxic to marine life at high concentrations and hence concentrations were compared to ANZECC (2000) trigger values. All measured NH3N concentrations in Lyttelton Harbour/Whakaraupō were below the ANZECC (2000) trigger value (0.5mg/L) providing protection for 99% of marine species. The NH3N concentrations in the six waterways were all below 0.5 mg/L. That is, fresh water flows into the harbour are not resulting in potentially toxic NH3N concentrations in the harbour water. NH3N concentrations in the wastewater effluent discharged into the harbour have the potential to be toxic to marine life at the point of, and in the vicinity of, each discharge. NH3N concentrations in Diamond Harbour effluent were as high as 27 mg/L with concentrations higher than 0.5 mg/L in 65%, and concentrations higher than 5 mg/L in 26% of effluent samples collected since January 2005.



Figure 6-1: Dissolved oxygen saturation (%) at harbour sites in 2007- 2008

NH3N concentrations in Governors Bay effluent were as high as 22 mg/L with concentrations higher than 0.5 mg/L in 83% and concentrations higher than 5 mg/L in 59%, of effluent samples collected since January 2005. There are no NH3N data for the Lyttelton outfall. Effluent dilutions of up to 54 times would be required to achieve an NH3N concentration providing protection for 99% of marine species. There are no data available that would allow for assessment of the actual impact of these NH3N concentrations on harbour ecology. Nitrogen and phosphorus The concentrations of nitrogen and phosphorus normally limit primary production (plant growth) in water. In the marine environment dissolved inorganic nitrogen (DIN) (DIN = NNN+NH3N) is considered the critical limiting nutrient for phytoplankton (plant plankton) growth (NRC, 2001). Although high DIN concentrations can lead to excessive phytoplankton growth (which can result in an algal bloom), the relative availability of nitrogen and phosphorus, i.e. the N:P ratio, the flushing, light regime, light penetration into the water column, temperature and the availability of other chemicals such as silica and iron are also important (ANZECC, 2000; NRC, 2001). Under optimal conditions, phytoplankton will take up nutrients in the ratio C:N:P of 106:16:1 (Redfield et al, 1963), i.e. when the nutrients are available in this ratio phytoplankton growth will not be limited. If the ratio of N:P is less than 16:1 then growth is nitrogen limited and if it is greater than 16:1 growth is phosphorus limited (NRC, 2001). The ratio of DIN:DRP (N:P) was calculated for all samples at all sites (Figure 6-2). The majority of samples from each site had an N:P ratio of less than 16:1. However, an N:P ratio of greater than 16:1 occurred at eight of the 11 sites on one or more sampling occasion. These results indicate that phytoplankton growth in Lyttelton Harbour/Whakaraupō is limited by the concentration of DIN. That is, inputs of DIN to harbour water could stimulate phytoplankton growth and potentially result in algal blooms.

Cha

rteris

Bay

Gov

erno

rs B

ay

Qua

il-R

apak

i

Cor

sair

Bay

Chu

rch

Bay

Inne

r por

t ent

ranc

e

Pur

au B

ay

Rip

apa-

Bat

tery

Har

bour

ent

ranc

e

70

75

80

85

90

95

100

105

110D

O %

sat

urat

ion



Figure 6-2: N:P ratio in all samples collected from each of the harbour sites

6.1.3 Chlorophyll-a concentrations Chlorophyll-a concentration is used as a measure of the concentration of phytoplankton. Phytoplankton abundance is influenced by water temperature and light and is thus seasonal. Weather and sea conditions, dissolved nutrient concentrations, the N:P ratio and the availability of other chemicals such as silica and iron (ANZECC, 2000) also influence phytoplankton abundance and persistence. The chlorophyll-a concentrations in Lyttelton Harbour/Whakaraupō ranged from 0.4 to 7.4 μg/L. A chlorophyll-a concentration of 5 μg/L has been found to cause physical discolouration of surface waters (Eppley et al., 1977) and hence concentrations of greater than 5 μg/L are reported in Table 6.1.

Table 6.1: Chlorophyll-a concentrations > 5 μg/L at harbour sites, 2007-2008

Date Site Concentration (μg/L)

3-Dec-07 Ripapa-Battery 7.4

Governors Bay 7.1

Quail-Rapaki 6.7

Corsair Bay 6.4

13-Feb-08 Inner port entrance 5.3

10-Mar-08 Corsair Bay 6.4

23-Jan-08

Charte

Gove

Quail-R

Corsair

Church In

Purau B

a

Ripapa

Ripa H

a

0

5

10

15

20

25

30

35

40

45

50

55

60

N:P



These higher chlorophyll-a concentrations only occurred at some sites and only occurred in summer and early autumn. It is possible that the phytoplankton concentrations reported in Table 6.1 caused some discolouration of the water although the concentrations are not particularly high. That is, they are not indicative of a significant phytoplankton bloom. An example of a phytoplankton bloom chlorophyll-a concentration is 189.5 μg/L which was recorded in the Avon-Heathcote Estuary/Ihutai in March 2008. This high concentration resulted in a very obvious red-brown discolouration of estuary water. Phytoplankton blooms do occur in Lyttelton Harbour/Whakaraupō from time to time. In February 2009 the bloom of Gymnodinium spp. resulted in lime green discoloured water in the Port of Lyttelton, Corsair Bay and Church Bay.

6.1.4 Total suspended solids concentrations The transport of soil off the land with rainfall and/or re-suspension of fine seabed sediments as a result of shallow water in combination with wind generally account for elevated total suspended solids (TSS) concentrations in Lyttelton Harbour/Whakaraupō water. Total suspended solids concentrations were highest at the shallowest sites and decreased with increasing water depth. The range in TSS concentrations also decreased with increasing water depth. There are no guideline trigger values for marine TSS concentrations against which the recorded concentrations can be compared. Elevated TSS concentrations:

• reduce light availability through the water column affecting primary production • impact on feeding and hence growth and reproductive condition of marine species and in

particular filter feeders. The total suspended solids within the water column eventually settle to the seabed. This settling has the potential to cover hard (rocky shore) surfaces with fine particles and add more sediment to the soft (mud, sand) seabed. That is, high TSS concentrations have the potential to have a range of ecological impacts over and above those that impact the water column. The input of soil, i.e. terrigenous sediment, is a significant ecological health issue for Lyttelton Harbour/Whakaraupō. There are no data on the actual quantities of soil entering Lyttelton Harbour/Whakaraupō each year. However, Curtis (1985) estimated that on average 44 300 t/year of loess and loess colluvium is eroded from the harbour catchments. Much of this terrigenous sediment is deposited in the upper harbour (Hart, 2004). There are concerns that the quantity of soil entering harbour water is increasing as a consequence of an increase in land disturbance activities. Erosion scars, subdivision developments, road cutting and quarries expose the loess and loess colluvium to the elements. Low volumes of terrigenous sediment settling onto the soft sediment seabed can cause subtle chemical changes to the seabed sediments that may ultimately alter the structure of the biological community. The chemistry of newly deposited terrigenous sediment is different to that of the existing seabed soft sediment (Gibbs and Hewitt, 2004). The addition of the terrigenous sediment can also change the sediment grain size distribution. The grain size distribution of seabed soft sediment affects sediment organic matter content, pore-water chemistry and microbial and microphytobenthos abundance and species composition (Snelgrove and Butman, 1994). This combination of factors influences the presence and abundance of sediment-dwelling species (infauna – within the sediment, epifauna – on the sediment). Thus changes in the grain size distribution of seabed sediment can result in changes to the biological community. From work that has been carried out in the Auckland region on the effects of increased sedimentation rates, suspended sediment concentrations and mud content on benthic fauna, a list of sediment sensitive New Zealand species has been constructed (Gibbs and Hewitt, 2004). This list of 31 species can be found in the Gibbs and Hewitt (2004) report. The deposition of suspended solids onto hard substrate (rocky/cobble), intertidal and subtidal surfaces has the potential to have a significant adverse effect on the biological communities. These communities are not adapted to live in a soft sediment habitat. Terrigenous sediment that settles (at depths of < 5 mm) and persists, on hard rocky/cobble substrate, including cracks and crevices and under cobbles could smother and kill the plants and animals present. The accumulation of fine



sediment in such habitats will also have an impact on the egg masses deposited under cobbles at certain times of the year and affect the settlement and survival of juveniles.

6.2 Water quality for contact recreation and shellfish gathering There are three water quality classes within Lyttelton Harbour/Whakaraupō as specified by the Regional Coastal Environment Plan (Environment Canterbury, 2005). The water quality classes and the geographic areas in which they apply (Figure 6-3) are:

• water managed for the maintenance of aquatic ecosystems (Coastal AE) - the operational area of the Port of Lyttelton.

• water managed for contact recreation and the maintenance of aquatic ecosystems (Coastal CR) - the western part of Lyttelton Harbour/Whakaraupō.

• water managed for shellfish gathering, contact recreation, and the maintenance of aquatic ecosystems (Coastal SG) - Rapaki and the outer or eastern part of Lyttelton Harbour/Whakaraupō.

Figure 6-3: Lyttelton Harbour/Whakaraupō water quality classes

6.2.1 Water managed for the maintenance of aquatic ecosystems (Coastal AE) The water quality class of water managed for the maintenance of aquatic ecosystems applies to the operational area of the Port of Lyttelton. One of the criteria for Coastal AE water is that the



concentration of dissolved oxygen shall not be reduced to less than 80% of saturation concentration as a result of any discharge of a contaminant or water. At the Inner port entrance, the only sampling site within this water quality class, all measured DO saturations were above 80%.

6.2.2 Water managed for contact recreation (Coastal CR) The concentration of the faecal indicator organism enterococci is used to assess the quality of the water for contact recreation. Enterococci concentrations are monitored routinely over the summer months at eight sites around the harbour. Each site has a suitability for recreation grade. Rapaki Bay, Cass Bay, Charteris Bay, Church Bay and Diamond Harbour Beach have a GOOD, and Corsair Bay, Governors Bay and Purau Bay have a FAIR, suitability for recreation grade. “Good” indicates the site is suitable to swim at most of the time but there may be exceptions, for example, after rainfall. “Fair” indicates that the site is generally satisfactory for swimming though there are typically a number of potential sources of faecal contamination. The water quality class of water managed for contact recreation, which applies to the western part of Lyttelton Harbour/Whakaraupō and includes all of the above sites, is being met.

6.2.3 Water managed for shellfish gathering (Coastal SG) Routine monitoring of overlying water faecal coliform concentrations to determine if the shellfish are safe to eat is undertaken in Rapaki Bay. Faecal coliform concentrations in Rapaki Bay water indicate that shellfish in the bay are not always safe to eat. An investigation, undertaken to pinpoint the source of the faecal coliforms in Rapaki Bay water, determined that land runoff, stormwater and seabed sediments were the likely sources. Sampling of micro-organism concentrations in the flesh of shellfish collected from various sites around the harbour In June 2009 determined that pipis from Rapaki Bay and blue mussels from Pile Bay and Livingtone Bay in the outer or eastern part of the harbour were suitable/safe for consumption. Blue mussels collected from North Quail Island and Kamautaurua (Shag Reef) in the western part of the harbour were not suitable/safe for consumption. The water quality class of water managed for shellfish gathering applies to Rapaki and the outer or eastern part of Lyttelton Harbour/Whakaraupō. The results from flesh testing of shellfish in 2009 indicate this classification is being met. However, results from the routine monitoring of overlying water faecal coliform concentrations in Rapaki indicate the classification is not typically met because general runoff and stormwater and possibly re-suspended seabed sediment influence faecal coliform concentrations in the sea water in this bay.

7 Future investigations and monitoring This report presents an evaluation of the quality of, and the factors affecting, Lyttelton Harbour/Whakaraupō water. The water within the harbour consists of tidal exchange water from Pegasus Bay/nearshore oceanic water in combination with freshwater from streams, stormwater and three wastewater outfalls. This assessment of factors influencing Lyttelton Harbour/Whakaraupō water quality has been limited by the lack of stream/creek flow data. The measurement of flows on the days of water quality sampling would have allowed for the calculation of the daily and yearly mass loads of nutrients, faecal indicator organisms and total suspended solids flowing into the harbour. It would have then been possible to compare the mass loads of nutrients and faecal indicator organisms from streams/creeks with those from wastewater outfalls. In this study the impact of wastewater effluent and waterway flows on harbour water quality was assessed at sites some distance away from the inputs. To better assess the mixing and zone of measurable impact of these inputs on harbour water quality specific investigations are required. Water



quality sampling sites need to be located close to and at set distances away from each source. The ideal would be to sample out from the waterways over a range of water flows. In order to assess the state of the water quality in Lyttelton Harbour/Whakaraupō in the face of increasing urbanisation, land use changes and port developments I recommend that routine water quality sampling be undertaken at sites throughout the harbour. The minimum would be monthly sampling for a year every five years. For any future assessment of the influence of wastewater effluent and freshwater flows on Lyttelton Harbour/Whakaraupō water quality I recommend that there be synchrony of sampling the harbour water, streams/creeks and wastewater outfalls. That is the waterways (water quality and flows), wastewater effluent quality and harbour water quality sampling are either on the same day, or the waterways and effluent sampling is on the day prior to harbour sampling. In this study it was found that:

• the median NH3N, NNN and TN concentrations in Livings Spring Creek were about twice that found in any of the other waterways.

• the maximum TP concentration in Rapaki Stream was about twice that of any of the other waterways.

I recommend that investigations be undertaken to determine the sources of these nutrients to Living Springs Creek and Rapaki Stream. Such investigations will initially involve sampling at various locations down each waterway. The concentration of the faecal indicator organism E. coli indicates there is some faecal contamination in all of the waterways. I recommend that investigations be undertaken to determine the sources of faecal contamination to Living Springs Creek, Teddington Stream, Te Wharau Stream and Purau Stream. Such investigations will initially involve sampling at various locations down each waterway. It could also involve detailed analyses to determine if the faecal contamination originates from humans, other mammals or birds. The input of soil is an ongoing and major ecological issue for this harbour. While data could be collected to determine the quantities of soil/sediment that are entering the harbour via the streams, stricter on-land erosion control measures are required to reduce these quantities.

8 Acknowledgements The author wishes to thank staff of Environment Canterbury, and in particular the seasick-prone Julie Edwards, for collection of routine harbour samples. Waterway samples were collected by Julie Edwards and Fay Farrant, while Michele Stevenson and Richard Purdon collected harbour samples during the heavy rainfall in late July 2008. The water samples were analysed by the laboratory staff of Cawthron Institute and Environment Canterbury. Thanks to the Christchurch City Council (CCC) for the provision of data and maps and to Mike Bourke from CCC for answering specific queries. Thanks also go to Mike Day and Paul Kelly from the Lyttelton Port Company Limited who provided information on request. This report was reviewed by Michele Stevenson and Tim Davie from Environment Canterbury. Dr. Bethany Roberts with assistance from Paul Barter and Ross Sneddon of the Cawthron Institute peer reviewed this report.



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Redfield, A.C., Ketchum, B.H. and Richards, F.A. 1963. in: The Sea: Ideas and Observations on Progress in the Study of the Seas, ed. M.N. Hill. Vol. II. Pp 26-77. Interscience, New York.

Sheridan, H.K. Fogarty, L.R. and Wright, C. 2003. Escherichia coli and Enterococci at Beaches in the Grand Traverse Bay, Lake Michigan: Sources, Characteristics, and Environmental Pathways. Environmental Science and Technology 37:3275-3282.

Snelgrove, P.V.R. and Butman, C. A. 1994. Animal-sediment relationships revisited: Cause versus effect. Oceanography and Marine Biology: an Annual Review 32:111-177.

Spigel, R.H. 1993. Flushing capability of Lyttelton Harbour/Whakaraupo: Review of existing knowledge and recommendations for future work. Report submitted to Royds Garden Ltd. in relation to water right applications for the proposed Lyttelton sewage outfall. 23pp.

Vincent, V.C and Thomas, M.P. 1997. Urban runoff pollution: An Overview. Environmental Education and Information 16(2): 185-196.



Appendix 1: Sampling sites

Harbour sites

Stream sites

Site Description Site ID

Grid Reference NZMS 260 map

series

Te Wharau Stream - bridge at Main Road SQ34569 M36:8601-2811

Living Springs Creek - above Main Road SQ34626 M36:8160-2942

Zephyr Stream - above Governors Bay Road SQ34884 M36:8174-3192

Purau Stream - 50m Above Main Road bridge SQ35236 M36:8988-2970

Rapaki Stream - above the bridge closest to jetty SQ35237 M36:8427-3329

Site Description Site IDGrid Reference NZMS

260 map series Years sampled

Charteris Bay SQ30661 M36:8573-2968 1992-1994, 2002-2003, 2007-2008

Governors Bay SQ30651 M36:8237-3118 1992-1994, 2002-2003, 2007-2008

Quail-Rapaki SQ35146 M36:8445-3226 2007-2008

Corsair Bay SQ30632 M36:8560-3305 1992-1994, 2002-2003, 2007-2008

Inner Port entrance SQ30680 M36:8707-3321 1992-1994, 2002-2003, 2007-2008

Church Bay SQ35147 M36:8706-3074 2007-2008

Purau Bay SQ30673 M36:8965-3083 1992-1994, 2002-2003, 2007-2008

Battery-Ripapa SQ35148 M36:8967-3280 2007-2008

NE of Ripapa Island SQ32585 N36:9031-3249 1992-1994, 2002-2003

Harbour entrance SQ32587 N36:9465-3403 1992-1994, 2002-2003, 2007-2008



Appendix 2: Description of parameters

Phosphorus Phosphorus occurs in natural waters almost solely as phosphates. These are classified as orthophosphates, condensed phosphates and organically bound phosphates. They occur in solution, in particles or detritus, or in the bodies of aquatic organisms. Phosphorus is essential to the growth of organisms and, particularly in fresh water, can be the nutrient that limits the primary productivity of a body of water. In instances where phosphate is a growth-limiting nutrient, the discharge of raw or treated wastewater, agricultural drainage, or certain industrial wastes to that water may stimulate the growth of phytoplankton, algae and other aquatic plants to nuisance quantities. Phosphates also occur in bottom sediments and in biological sludges, both as precipitated inorganic forms and incorporated into organic compounds (APHA, 1998). Dissolved reactive phosphorus is a form of dissolved phosphate (orthophosphate) that is available immediately for plant and algal growth. Total phosphorus is a measure of the concentration of orthophosphates, condensed phosphates and organically bound phosphates in the water. This includes both dissolved and suspended phosphates. Nitrogen In water, the forms of nitrogen of greatest interest are, in order of decreasing oxidation state, nitrate, nitrite, ammonia, and organic nitrogen. All these forms of nitrogen, as well as nitrogen gas (N2) and dinitrogen oxide (N2O), are biologically interconvertible and are components of the nitrogen cycle (APHA, 1998). The nitrate ion (NO3

-) is the common form of combined nitrogen found in natural waters. It may be biochemically reduced to nitrite (NO2

-) by denitrification processes, usually under anaerobic conditions. The nitrite ion is rapidly oxidised to nitrate (Chapman, 1992). Nitrite and nitrate nitrogen (NNN, also called total oxidised nitrogen) is the sum two oxidised forms of inorganic nitrogen. It is reported in terms of the sum of concentration of nitrogen that was in the forms of nitrate and nitrite. Ammonia occurs naturally in water bodies arising from the breakdown of nitrogenous organic and inorganic matter in soil and water, excretion by biota, reduction of the nitrogen gas in water by micro-organisms and from gas exchange with the atmosphere. It is also discharged into water bodies by some industrial processes and as a component of municipal or community waste (Chapman, 1992). Compared to nitrate, ammonia is usually a very minor component of plant available nitrogen. The main concern with ammonia concentrations in water bodies is toxicity effects on aquatic ecosystems. In water ammonia occurs in two forms; the ammonium ion (NH4

+) and un-ionised ammonia (NH3). The proportion of these chemical forms is dependent on the pH, temperature and ionic composition of the water. The un-ionised form of ammonia (NH3) is the most toxic, although toxicity effects also occur with the ammonium ion (ANZECC, 2000). Measurement of ammonia concentrations usually measures total ammonia (NH3+ NH4

+). Dissolved inorganic nitrogen is a measure of the nitrogen available to plants, and is the sum of the concentrations of nitrate and nitrite-nitrogen and ammonia nitrogen. Nitrogen is essential to the growth of organisms and, particularly in sea water, can be the nutrient that limits the primary productivity of a body of water. In instances where nitrogen is a growth-limiting nutrient, the discharge of raw or treated wastewater, agricultural drainage, or certain industrial wastes to that water may stimulate the growth of phytoplankton, algae and other aquatic plants to nuisance quantities. Total nitrogen is a measure of all nitrogen in the water; both inorganic and organic nitrogen forms.



Chlorophyll-a Chlorophyll-a concentration is used as a measure of the amount of plant plankton (phytoplankton) in the water, i.e., the more plant plankton in the water the higher the chlorophyll-a concentration. Chlorophyll-a concentration of 5 μg/L has been found to cause physical discolouration of surface waters (Eppley et al., 1977). High chlorophyll-a concentrations occur when there is a phytoplankton bloom. Total suspended solids Total suspended solids (TSS) are particles of all sizes within the water column. These particles can originate from nearby land or the seabed. The particles that originate from the land are generally washed into waterways during rainfall and from there flow into the sea. Factors that can contribute to high TSS concentrations in the streams include bank erosion due to lack of vegetation and/or stock trampling, soil erosion due to vegetation clearance, and earthworks. Sediment particles from the seabed can be stirred up by swell waves or wind induced waves. Contaminants such as nutrients and heavy metals attach to fine sediment particles and are washed into the stream and then the sea where they settle to the seabed with the sediment or detach and become soluble in the water column. Turbidity Visible clarity of water is important for aesthetic and safety aspects of recreational use of water bodies. Reduction in clarity can affect the behavioural pattern of fish and macro-invertebrates, especially of the migratory and predatory species. Clarity of the water will also affect primary production such as algal growth. Turbidity is a relative measurement of light scattering by suspended particles in water. Informally, turbidity measurement is considered synonymous with ‘cloudiness’ (loss of visual clarity) (MfE, 1994). Salinity This is a measure of how salty the water is. The sea water 2.5 to10 kilometres from shore in Pegasus Bay typically has a salinity of 33 -34.5 ppt (parts per thousand). Enterococci Enterococci are used as an indicator of the potential presence of faecal matter in seawater. The presence of high concentrations of enterococci in water indicates the likely presence of faecal material and, with it, the possibility that other disease-causing organisms may be present. Faecal contamination of waters can occur through inadequately treated sewage, stormwater runoff, septic tanks, runoff from pastoral farm land, and from wildlife such as waterfowl living in and around waterways.


arbour/ Whakaraupō

82 Environm


eport

Appendix 3: Nutrient analyses and detection limits

Determinand Analysis provider Analytical method Time Period Detection Limit Units

CIN Laboratory APHA 418C Cawthron method 1992- April 1994 0.005 mg/L

CIN Laboratory Cd reduction APHA reagents Buffer = NH4Cl/EDT May - June 1994 0.005 mg/L

Ecan laboratory APHA 4500 NO3 - F (19th ED, 1995) 2000-2008 0.001 mg/L

CIN Laboratory Limnology and Oceanography Cawthron method 1992-1994 0.005 mg/L

Ecan laboratory APHA 4500 NH3-F - modified (19th ED, 1995) 2000-2008 0.005 mg/L

CIN Laboratory Photo-oxidation then NNN Cawthron method 1992-1994 mg/L

Ecan laboratory APHA 4500-N C modified (19th ED, 1995) 2000-2008 0.08 mg/L

CIN Laboratory APHA 424F modified Cawthron method 1992-1994 0.003 - 0.001 mg/L

Ecan laboratory APHA 4500-P B, E modified (19th ED, 1995) 2000-2008 0.003 mg/L

CIN Laboratory APHA 424 C3 Persulphate Digest Cawthron method 1992-January 1994 0.008 mg/L

CIN Laboratory APHA 424 C1 Perchloric acid Digestion Cawthron February-June 1994 0.008 mg/L

Ecan laboratory APHA 4500-P B (19th ED, 1995) 2000-2008 0.008 mg/L

Total phosphorus (TP)

Dissolved reactive phosphorus (DRP)

Total nitrogen (TN)

Total ammonia-nitrogen (NH3N)

Nitrate-nitrite nitrogen (NNN)



Appendix 4 Summary data for parameters



1992-1993 Number of samples = 11


Governors Bay

Charteris Bay

Corsair Bay

Inner port entrance Purau Bay Ripapa Harbour

entrance

Minimum 0.006 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005Median 0.015 0.021 0.02 0.016 0.018 0.016 0.0165Mean 0.031 0.028 0.030 0.026 0.025 0.017 0.019SD 0.031 0.024 0.026 0.028 0.021 0.012 0.015Maximum 0.091 0.066 0.074 0.092 0.062 0.038 0.048

Minimum <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005Median 0.029 0.019 0.022 0.043 0.017 0.020 0.023Mean 0.034 0.030 0.034 0.044 0.047 0.033 0.032SD 0.034 0.036 0.031 0.042 0.078 0.035 0.034Maximum 0.11 0.11 0.089 0.14 0.27 0.1 0.087

Minimum 0.09 0.11 0.1 0.1 0.03 <0.08 0.088Median 0.2 0.19 0.21 0.16 0.2 0.19 0.165Mean 0.204 0.195 0.197 0.177 0.186 0.169 0.160SD 0.059 0.059 0.059 0.061 0.117 0.072 0.055Maximum 0.28 0.33 0.27 0.28 0.48 0.27 0.24

Minimum 0.012 0.006 0.008 0.009 0.004 0.004 0.003Median 0.021 0.016 0.018 0.021 0.014 0.017 0.016Mean 0.020 0.015 0.018 0.022 0.014 0.015 0.014SD 0.005 0.006 0.006 0.010 0.007 0.007 0.007Maximum 0.03 0.025 0.027 0.044 0.025 0.025 0.022


Total phosphorus (mg/L)

Ammonia nitrogen (mg/L)

Nitrite-nitrate nitrogen (mg/L)

Total nitrogen (mg/L)

Dissolved reactive phosphorus (mg/L)

Governors Bay

Charteris Bay

Corsair Bay


entrance

Minimum <0.005 <0.005 <0.005 <0.005 <0.005 0.005 <0.005Median 0.014 0.013 0.0155 0.02 0.01 0.014 0.015Mean 0.015 0.018 0.018 0.024 0.011 0.016 0.027SD 0.013 0.013 0.014 0.016 0.010 0.011 0.024Maximum 0.047 0.039 0.043 0.047 0.035 0.047 0.068













Governors Bay

Charteris Bay

Corsair Bay


entrance



Minimum 0.14 0.14 0.13 0.16 0.09 0.12 <0.08Median 0.2 0.2 0.2 0.21 0.2 0.16 0.16Mean 0.20 0.19 0.21 0.23 0.19 0.17 0.20SD 0.05 0.04 0.07 0.06 0.06 0.04 0.09Maximum 0.29 0.27 0.34 0.38 0.29 0.26 0.39


Minimum 0.008 <0.008 <0.008 0.008 <0.008 <0.008 <0.008Median 0.02 0.016 0.019 0.018 0.016 0.016 0.017Mean 0.027 0.023 0.025 0.022 0.025 0.019 0.019SD 0.018 0.017 0.017 0.014 0.029 0.014 0.011Maximum 0.069 0.064 0.055 0.053 0.11 0.052 0.041

Minimum 0.5 0.2 0.5 0.7 0.4 0.8 0.7Median 1.5 0.9 1.9 2.2 1.7 1.4 2.4Mean 1.7 1.3 2.6 2.6 1.6 1.7 2.4SD 1.1 1.0 1.9 1.8 0.8 0.9 1.6Maximum 3.7 2.8 5.9 7 2.8 3.1 6.3

Minimum 4.1 3.5 3.6 2.5 3 2.1 2Median 9 5 5.5 3.7 4.6 4 3.5Mean 8.4 6.8 6.3 3.9 7.5 4.8 4.1SD 4.4 4.0 2.3 1.0 7.8 3.6 2.0Maximum 19 17 9.7 6.2 30 14 8



Turbidity (NTU)








Governors Bay

Charteris Bay

Quail-Rapaki

Corsair Bay

Church Bay

Inner port entrance Purau Bay

Ripapa-Battery

Harbour entrance

Minimum 0.021 0.029 0.02 0.025 0.026 0.032 0.031 0.023 0.015Median 0.038 0.045 0.045 0.043 0.046 0.059 0.046 0.043 0.045Mean 0.038 0.053 0.047 0.049 0.052 0.061 0.046 0.048 0.042SD 0.010 0.021 0.026 0.021 0.019 0.019 0.009 0.017 0.014Maximum 0.054 0.093 0.12 0.091 0.1 0.1 0.06 0.088 0.064

Minimum <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005Median 0.016 0.015 0.007 0.017 0.010 0.021 0.011 0.009 0.013Mean 0.020 0.022 0.018 0.023 0.019 0.028 0.027 0.020 0.029SD 0.019 0.021 0.023 0.022 0.022 0.025 0.028 0.024 0.026Maximum 0.06 0.061 0.076 0.073 0.075 0.082 0.089 0.081 0.073

Minimum 0.11 0.1 0.11 0.1 0.04 0.12 <0.08 <0.08 <0.08Median 0.15 0.15 0.15 0.15 0.16 0.16 0.14 0.13 0.12Mean 0.17 0.17 0.16 0.15 0.16 0.16 0.13 0.13 0.12SD 0.06 0.06 0.05 0.04 0.07 0.03 0.05 0.04 0.03Maximum 0.33 0.32 0.26 0.21 0.31 0.22 0.21 0.18 0.15

Minimum 0.011 0.003 0.013 0.01 0.01 0.007 0.006 0.006 <0.003Median 0.024 0.023 0.025 0.022 0.021 0.023 0.017 0.019 0.015Mean 0.023 0.023 0.022 0.022 0.019 0.022 0.016 0.018 0.013SD 0.005 0.010 0.005 0.005 0.006 0.007 0.006 0.006 0.008Maximum 0.028 0.043 0.027 0.027 0.026 0.03 0.024 0.025 0.028


Minimum 0.5 0.5 1.3 1.4 1 0.4 0.6 1.4 0.8Median 1.8 1.7 2.0 2.6 1.6 2.1 2.1 2.4 2.1Mean 2.6 1.8 2.7 3.1 2.1 2.7 2.2 3.0 2.1SD 1.8 1.1 1.6 1.8 1.0 1.5 1.4 1.7 0.9Maximum 7.1 4.3 6.7 6.4 4.3 5.3 4.6 7.4 4.5

Minimum 6.1 5.1 8.8 9.4 7.4 5.2 6.7 8 3.5Median 20.5 13.5 14.5 14.5 14.5 9.3 11 12.5 8.35Mean 28.0 23.3 18.7 17.8 19.0 9.8 12.4 12.9 8.4SD 25.2 23.3 15.6 9.5 10.0 2.4 5.2 3.9 3.3Maximum 100 88 67 43 38 15 22 19 14

Minimum 3.9 2.4 4.1 4.3 3.6 2.4 3.2 3.1 0.6Median 9.3 6.95 6.4 6.4 5.45 4.45 4.45 5.45 3.55Mean 15.1 11.1 8.9 7.6 8.1 4.2 5.3 5.5 3.4SD 14.3 11.0 8.3 3.2 5.2 1.0 2.1 1.6 1.6Maximum 54 42 34 14 17 5.3 9.6 7.7 6.2

Minimum 88 86 88 87 85 85 85 87 90Median 93 93 90 94 94 94 96 95 99Mean 94 94 93 94 94 95 95 95 97SD 6 6 6 5 6 7 6 6 5Maximum 103 106 101 101 101 108 103 101 106Count 10 10 10 10 10 10 10 10 10



Total suspended solids (mg/L)

Turbidity (NTU)

Salinity (ppt)

Dissolved oxygen saturation (%)







arbour/ Whakaraupō

Environment C


87

Appendix 5: Between site comparison of nutrient concentrations in surface water Results from the two-tailed Wilcoxon Signed Rank Test Interpreting the table

The significant differences between sites are a higher concentration of the parameter at that site listed across the top of the table than at the site listed down the side of the table

* significant different between sites at p<0.05

** significant difference between sites at p<0.01

Blank cells indicate there was no significant difference between sites


arbour/ Whakaraupō

88 Environm


eport

Charteris Governors Corsair Inner Port entrance Purau Ripapa Harbour entranceDRP ** DRP * TN * NNN * TN *TP** TP ** TP * DRP * DRP **

Turbidity * Chlorophyll-a * TP **Chlorophyll-a **

NNN ** NNN * NNN *Chlorophyll-a * Chlorophyll-a *

TP ** TP * NNN *DRP *

Turbidity ** TP ** TP * TN * Turbidity * TN *Turbidity ** Turbidity **

NH3N * DRP ** DRP * DRP ** NNN * NNN ** TN *DRP * DRP * TP ** TP ** NH3N * NH3N * Chlorophyll-a *

TN * DRP * DRP ** DRP **DRP * DRP * DRP ** TP *

Chlorophyll-a *DRP * DRP ** TN * TN * NNN * NNN ** Turbidity ** NH3N *

Turbidity ** DRP * DRP * DRP ** TN * TN * TN *TP** TP * DRP * DRP * DRP ** DRP * DRP * DRP **Turbidity ** TP * TP *

TN* TN * TN * NNN *DRP * DRP * DRP ** DRP * DRP * DRP ** NH3N * Turbidity **

Turbidity * TP* TP * Turbidity * DRP * DRP * DRP **Turbidity ** Chlorophyll-a *

Ripapa

Harbour entrance

Low

er c

once

ntra

tion

Higher concentration

Charteris

Governors

Corsair

Inner Port entrance

Purau

Results from 1992-1993, 1993-1994 and 2002-2003 Green – 1992-1993 Blue – 1993-1994 Red – 2002-2003


arbour/ Whakaraupō

Environment C


89

Results from 2007-2008

Charteris Governors Quail-Rapaki Corsair Church Inner Port entrance Purau Ripapa-Battery Harbour entrance

Turbidity * Chlorophyll-a * Chlorophyll-a * Chlorophyll-a *

NH3N ** NH3N * NH3N ** NH3N *

TSS * NH3N * NNN * NNN *

Turbidity ** NNN * DO Saturation **DO *

TP * NH3N ** DO saturation *

TP * TP * DRP ** DRP ** NH3N * Chlorophyll-a * NNN *DRP * Chlorophyll-a ** NNN * DO saturation * DO saturation *

DRP * DO *Chlorophyll-a *

TP * TP * TSS ** TSS ** TSS ** TSS *TSS * TSS ** Turbidity ** Turbidity ** Turbidity * Turbidity **

Turbidity * Turbidity **

TN * TP * TP * DRP ** DRP ** NH3N * DRP * DO Saturation **

TP ** DRP ** DRP ** Chlorophyll-a * TSS * DRP ** Chlorophyll-a *DRP ** TSS ** TSS * Turbidity * Turbidity **TSS * Turbidity ** Turbidity *

Turbidity *TP * TN * TP * DRP ** DRP ** NH3N * NNN *

TP ** DRP ** Turbidity * TSS * NNN * DO saturation * DRP * DRP **TSS *

Turbidity *TN ** TN ** TN * TN * TP * TN ** TP * TP *TP ** TP ** TP * TP ** DRP ** TP * DRP * DRP **

DRP ** DRP ** DRP ** DRP ** TSS ** NH3N * TSS * Chlorophyll-a *

TSS * TSS ** TSS ** Chlorophyll-a * Turbidity ** DRP ** Turbidity ** TSS **Turbidity ** Turbidity ** Turbidity ** TSS ** Turbidity **

Turbidity **

Higher concentration

Charteris

Governors

Quail-Rapaki

Purau

Ripapa-Battery

Low

er C

once

ntra

tion

Corsair

Harbour entrance

Church

Inner Port entrance



Appendix 6: Wind direction and speed in each year of sampling Frequency of wind direction in each year of sampling Data source: NZ Metservice, recorder located in the inner port (Map reference M36:878 332) The data presented are a summary of the daily wind records that were measured every three hours (0300, 0600, 0900, 1200, 1500, 1800, 2100 and 2400 hours).

1992-1993 010 20

3040

50

60

70

80

90

100

110

120

130140

150160170

180190200

210220

230

240

250

260

270

280

290

300

310320

330340 350 1993-1994 0

10 2030

4050

60

70

80

90

100

110

120

130140

150160170

180190200

210220

230

240

250

260

270

280

290

300

310320

330340 350

2002-2003 010 20

3040

50

60

70

80

90

100

110

120

130140

150160170

180190200

210220

230

240

250

260

270

280

290

300

310320

330340 350

2007-2008 010 20

3040

50

60

70

80

90

100

110

120

130140

150160170

180190200

210220

230

240

250

260

270

280

290

300

310320

330340 350

The numbers around the edge of each circle are wind direction in degrees The circle radius is a measure of the percentage of the total number of records (including when there was no wind) at that wind direction, the maximum value being 20. The highest value is 18.7% for 60 degrees in 2002-2003.



Percentage occurrence of wind speeds (m/s) in each year of sampling

0

5

10

15

20

25

0

1.1-

2

2.1

-3

3.1-

4

4.1-

5

5.1-

6

6.1-

7

7.1-

8

8.1-

9

9.1-

10

10.1

-11

11.1

-12

12.1

-13

13.1

-14

14.1

-15

15.1

-16

16.1

-17

Wind speed (m/s)

Perc

enta

ge o

ccur

ence

1992-1993

1993-1994

2002-2003

2007-2008



Appendix 7: Parameter concentrations in six harbour streams/creeks


arbour/ Whakaraupō

Environment C


93

Ammonia nitrogen

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

1/09

/07

1/10

/07

1/11

/07

1/12

/07

1/01

/08

1/02

/08

1/03

/08

1/04

/08

1/05

/08

1/06

/08

1/07

/08

1/08

/08

1/09

/08

1/10

/08

1/11

/08

1/12

/08

1/01

/09

Date

NH

3N c

once

ntra

tion

(mg/

L)

Rapaki StreamZephyr StreamLiving Springs CreekTeddington StreamTe Wharau StreamPurau Stream

Total nitrogen

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1/09

/07

1/10

/07

1/11

/07

1/12

/07

1/01

/08

1/02

/08

1/03

/08

1/04

/08

1/05

/08

1/06

/08

1/07

/08

1/08

/08

1/09

/08

1/10

/08

1/11

/08

1/12

/08

1/01

/09

Date

TN c

once

ntra

tion

(mg/

L)


Nitrite-nitrate nitrogen

0

0.2

0.4

0.6

0.8

1

1.2

1/09

/07

1/10

/07

1/11

/07

1/12

/07

1/01

/08

1/02

/08

1/03

/08

1/04

/08

1/05

/08

1/06

/08

1/07

/08

1/08

/08

1/09

/08

1/10

/08

1/11

/08

1/12

/08

1/01

/09

Date

NN

N c

once

ntra

tion

(mg/

L)



arbour/ Whakaraupō

94 Environm


eport

Dissolved reactive phosphorus

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

1/09

/07

1/10

/07

1/11

/07

1/12

/07

1/01

/08

1/02

/08

1/03

/08

1/04

/08

1/05

/08

1/06

/08

1/07

/08

1/08

/08

1/09

/08

1/10

/08

1/11

/08

1/12

/08

1/01

/09

Date

DR

P co

ncen

trat

ion

(mg/

L)Rapaki StreamZephyr StreamLiving Springs CreekTeddington StreamTe Wharau StreamPurau Stream

Total phosphorus

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

1/09

/07

1/10

/07

1/11

/07

1/12

/07

1/01

/08

1/02

/08

1/03

/08

1/04

/08

1/05

/08

1/06

/08

1/07

/08

1/08

/08

1/09

/08

1/10

/08

1/11

/08

1/12

/08

1/01

/09

Date

TP c

once

ntra

tion

(mg/

L)


Total suspended solids

0

10

20

30

40

50

60

70

1/09

/07

1/10

/07

1/11

/07

1/12

/07

1/01

/08

1/02

/08

1/03

/08

1/04

/08

1/05

/08

1/06

/08

1/07

/08

1/08

/08

1/09

/08

1/10

/08

1/11

/08

1/12

/08

1/01

/09

Date

TSS

conc

entr

atio

n (m

g/L)


Turbidity

0

10

20

30

40

50

60

70

80

1/09

/07

1/10

/07

1/11

/07

1/12

/07

1/01

/08

1/02

/08

1/03

/08

1/04

/08

1/05

/08

1/06

/08

1/07

/08

1/08

/08

1/09

/08

1/10

/08

1/11

/08

1/12

/08

1/01

/09

Date

Turb

idity

(NTU

)




Appendix 8: Rainfall at Coopers Knob Rainfall on the days prior to sampling the six waterways

Day 5 Day 4 Day 3 Day 2 Day 127-Sep-07 0 12 3 0 119-Dec-07 2 4.5 0 0 156-Mar-08 17 16 3.5 0.5 0.526-Jun-08 0 0.5 7 0.5 021-Jul-08 0 2.5 7 5.5 020-Aug-08 0 0 4 1.5 1419-Sep-08 0 0 0 0 1821-Oct-08 0 0 1 0 018-Nov-08 0 0 0 0 017-Dec-08 2 0 0 5 0.5



Appendix 9: Details of harbour sampling sites and adjacent streams/creeks

Harbour site Waterways Distance of harbour site to a waterway

Corsair Bay 1 ephemeral 329 m to mouth of stream

Governors Bay4 ephemeral Zephyr Stream Living Springs Creek

705 m to mouth of Zephyr Stream 1760 m to mouth of Living Springs Creek

Charteris Bay 6 ephemeral Te Wharau Stream 1455 m to mouth of Te Wharau Stream

Church Bay 1 ephemeral 425 m to mouth of stream

Purau Bay 6 ephemeral Purau Stream 924 m to mouth of Purau Stream



Appendix 10: Volume of treated wastewater (m3/day) discharged from each of the outfalls in the five days prior to water quality sampling Data supplied by Christchurch City Council

Day 5 Day 4 Day 3 Day 2 Day 129-Jul-02 675 690 654 739 7609-Sep-02 721 655 605 701 7307-Oct-02 649 761 658 679 67723-Oct-02 628 714 756 697 65025-Nov-02 966 1006 720 787 80318-Dec-02 654 751 745 668 658

9-Jul-07 807 761 813 758 8076-Aug-07 886 847 782 717 18203-Sep-07 729 751 823 726 8488-Oct-07 1351 712 829 758 7817-Nov-07 744 710 851 909 8213-Dec-07 1003 842 911 693 88423-Jan-08 732 618 692 795 68313-Feb-08 696 624 773 761 116910-Mar-08 752 738 784 689 8069-Apr-08 709 671 707 940 77012-May-08 873 838 856 799 9003-Jun-08 881 873 831 910 859

Day 5 Day 4 Day 3 Day 2 Day 19-Jul-07 223 197 197 206 2066-Aug-07 254 217 228 391 3913-Sep-07 109 216 191 217 2178-Oct-07 342 221 220 220 2207-Nov-07 124 124 124 124 2033-Dec-07 212 208 238 226 22623-Jan-08 86 210 210 210 19313-Feb-08 213 236 236 236 22610-Mar-08 224 206 198 230 2309-Apr-08 258 258 258 237 23712-May-08 210 201 186 201 2013-Jun-08 220 173 280 280

Day 5 Day 4 Day 3 Day 2 Day 129-Jul-02 123 199 206 230 2199-Sep-02 218 124 196 208 2337-Oct-02 193 259 128 219 22123-Oct-02 198 221 229 203 20325-Nov-02 185 243 247 251 24118-Dec-02

9-Jul-07 168 162 157 151 1516-Aug-07 146 174 136 213 2133-Sep-07 153 144 139 128 1288-Oct-07 196 192 146 179 1797-Nov-07 156 173 173 173 1353-Dec-07 150 154 119 171 17123-Jan-08 122 180 180 180 13913-Feb-08 119 158 158 158 14810-Mar-08 149 160 126 166 1669-Apr-08 151 151 151 151 16512-May-08 193 157 167 155 1553-Jun-08

Lyttelton

Diamond Harbour

Governors Bay

No data

No data



Appendix 11: Total suspended solids Total suspended solids concentrations and water depth at the time of sampling at five sites Total daily rainfall on days 3, 2 and 1 prior to sampling and in the hours (day 0) prior to sampling (at Coopers Knob), maximum wind speed on days 3, 2 and 1 prior to sampling and in the hours (day 0) prior to sampling (at Port of Lyttelton) Rainfall data collected by Environment Canterbury Wind data collected by NZ Metservice

Total rain 3 Total rain 2 Total rain 1 Total rain 0 Max. WS3 Max. WS2 Max. WS1 Max. WS0

(mm) (mm) (mm) (mm) (m/s) (m/s) (m/s) (m/s)

9-Jul-07 1 2 10.5 0 9.78 8.75 15.44 5.66

6-Aug-07 0 0 0.5 7.5 11.84 10.81 10.3 4.12

3-Sep-07 0 6 0 0 6.18 6.18 5.15 4.12

8-Oct-07 0 0 0 0 5.66 12.87 12.87 9.27

7-Nov-07 0 12.5 10 0.5 3.09 8.75 7.21 2.57

3-Dec-07 0 2 14 0.5 7.72 10.3 8.75 4.12

23-Jan-08 0 0 5 2 2.57 6.18 7.21 5.15

13-Feb-08 0.5 2 0 0 12.35 6.69 7.72 5.66

10-Mar-08 0 0 0 0 6.18 8.24 10.81 4.63

9-Apr-08 0 1 0 0 7.72 4.12 3.09 5.15

12-May-08 2.5 1 0.5 0 4.63 3.09 6.18 4.63

3-Jun-08 0 0.5 0 1 10.3 7.21 12.35 6.69

Water depth TSS Water depth TSS Water depth TSS Water depth TSS Water depth TSS

m (mg/L) m (mg/L) m (mg/L) m (mg/L) m (mg/L)

9-Jul-07 2.26 12 2.96 5.1 4.33 9.9 3.44 12 2.91 14

6-Aug-07 1.96 22 2.96 46 4.11 17 3.26 16 2.96 35

3-Sep-07 1.83 34 2.56 17 3.76 8.8 2.76 11 2.66 13

8-Oct-07 1.01 42 1.62 27 3.16 14 2.28 9.9 1.58 11

7-Nov-07 0.96 15 1.66 14 3.11 20 2.3 14 1.56 13

3-Dec-07 1.96 37 2.26 27 4.08 20 3.2 26 2.36 15

23-Jan-08 0.39 100 1.11 88 2.46 67 1.56 21 1.09 28

13-Feb-08 2.06 21 2.81 13 4.13 17 3.16 43 2.86 23

10-Mar-08 0.81 15 1.56 12 2.89 15 1.93 23 1.66 11

9-Apr-08 0.56 12 1.31 11 2.66 11 1.71 15 1.33 38

12-May-08 1.86 6.1 2.76 5.9 3.94 12 3.03 9.4 2.76 20

3-Jun-08 0.96 20 1.56 13 3.14 13 2.31 13 1.51 7.4

Church BayGovernors Bay Charteris Bay Quail Rapaki Corsair Bay


arbour/ Whakaraupō

Environment C


99

Appendix 12: Faecal coliform and enterococci concentrations in the discharged wastewater and the receiving environment Data supplied by Christchurch City Council Governors Bay outfall

Sew

age

sam

ple

date

Faec

al c

olifo

rms

in

disc

harg

e (c

fu/1

00m

l)

Ent

eroc

occu

s in

di

scha

rge

(cfu

/100

ml)

Rec

eivi

ng e

nviro

nmen

t sa

mpl

e da

te

Faec

al c

olifo

rms

(cfu

/100

mL)

Ent

eroc

occi

(c

fu/1

00m

L)

Faec

al c

olifo

rms

(cfu

/100

mL)

Ent

eroc

occi

(c

fu/1

00m

L)

Faec

al c

olifo

rms

(cfu

/100

mL)

Ent

eroc

occi

(c

fu/1

00m

L)

Faec

al c

olifo

rms

(cfu

/100

mL)

Ent

eroc

occi

(c

fu/1

00m

L)

6-Jan-04 15 6 6-Jan-04 <2 5 <2 5 <2 <5 <2 5

14-Jan-04 10 <10 14-Jan-04 <2 <10 <2 <10 <2 <10 <2 <10

20-Jan-04 10 8 20-Jan-04 <10 10 <10 <10 <2 10 <10 10

27-Jan-04 10 <10 27-Jan-04 <2 10 <10 <10 <2 <10 <2 <10

12-Jan-05 150 13-Jan-05 <1 NR <10 NR <1 NR <1 NR

4-Jan-06 <10 <10 4-Jan-06 <10 <10 <10 <10 <10 <10 <10 10

11-Jan-06 <10 11-Jan-06 <10 <10 <2 <10 <2 <10 <2 <10

26-Jan-06 <10 26-Jan-06 <2 <10 <10 <10 2 <10 <10 <10

3-Jan-07 36 10 4-Jan-07 <10 <10 <10 <10 <10 <10 <10 <10

10-Jan-07 1500 11-Jan-07 <10 <10 <10 <10 <10 <10 <10 <10

19-Jan-07 100 19-Jan-07 <10 14 <10 16

22-Jan-07 6200 23-Jan-07 <2 <10 <2 <10 <2 <10 <2 <10

7-Jan-08 700 170 7-Jan-08 <10 <10 <10 <10 <10 <10 <10 <10

9-Jan-08 <10 9-Jan-08 <10 <10 <10 <10

22-Jan-08 2900 22-Jan-08 <10 <10 <10 <10 <10 <10 <10 <10

24-Jan-08 2000 24-Jan-08 <10 <10 <10 <10 <10 <10 <10 <10

Receiving environment

10-20m north of outfall 10-20m south of outfall 10-20m east of outfall 10-20m west of outfall

100 Environm


eport


arbour/ Whakaraupō

Diamond Harbour outfall

Sew

age

sam

ple

date

Faec

al c

olifo

rms

in

disc

harg

e (c

fu/1

00m

l)

Ente

roco

ccus

in

disc

harg

e (c

fu/1

00m

l)

Rec

eivi

ng e

nviro

nmen

t sa

mpl

e da

te

Faec

al c

olifo

rms

(cfu

/100

mL)

Ente

roco

cci

(cfu

/100

mL)

Faec

al c

olifo

rms

(cfu

/100

mL)

Ente

roco

cci

(cfu

/100

mL)

Faec

al c

olifo

rms

(cfu

/100

mL)

Ente

roco

cci

(cfu

/100

mL)

Faec

al c

olifo

rms

(cfu

/100

mL)

Ente

roco

cci

(cfu

/100

mL)

12-Jan-05 1700 13-Jan-05 <1 <1 1 <126-Jan-05 5000 27-Jan-05 <2 <10 <2 <10 2 <10 1 <104-Jan-06 21000 6500 4-Jan-06 <10 <10 <10 <10 <10 <10 <10 <1011-Jan-06 90 11-Jan-06 <2 10 <2 <10 <2 <10 <2 <1018-Jan-06 1700 18-Jan-06 <2 <2 20 32 <2 2 4 226-Jan-06 18 26-Jan-06 <2 <10 <2 <10 <2 <10 <2 <103-Jan-07 260 85 4-Jan-07 <10 <10 <10 <10 <10 <10 <10 <1010-Jan-07 1,100 11-Jan-07 <10 <10 <10 <10 <10 <10 <10 <1022-Jan-07 <10 23-Jan-07 2 <10 <2 <10 4 <10 <2 <107-Jan-08 <10 <10 7-Jan-08 <10 <10 <10 <10 <10 <10 <10 <109-Jan-08 <10 9-Jan-08 <10 <10 <10 <1022-Jan-08 <10 22-Jan-08 <10 <10 <10 <10 <10 <10 <10 <1024-Jan-08 <9 24-Jan-08 <10 <10 <10 <10 <10 <10 <10 <10

50m east of outfall 50m west of outfall

Sewage discharge Receiving environment 50m north of outfall 50m south of outfall



Appendix 13: Suitability for recreation grades Two components are integrated to produce the suitability for recreation grade (SFRG) for a site (MfE/MoH, 2003). These are:

• Historic enterococci results (the ideal being 5 years of data) (MAC), which provide a measure of the general water quality over an extended period of time. The MAC is based on the 95 % value.

• The Sanitary Inspection Category (SIC), which represents a measure of the susceptibility of a water body to faecal contamination.

There are five SFRG – Very good, good, fair, poor and very poor. n = number of samples Corsair Bay

Year n 95%ile MAC SIC SFRG 2002/2003 69 442 C Moderate Fair 2003/2004 70 490 C Moderate Fair 2004/2005 69 535.5 D Moderate Poor 2005/2006 68 581 D Moderate Poor 2006/2007 70 400 C Moderate Fair 2007/2008 71 393.5 C Moderate Fair 2008/2009 73 256.5 C Moderate Fair

The potential sources (SIC) of faecal contamination at this site (used to generate the SIC grade) are:

• Stream discharging close to the recreational area with the stream potentially affected by: - run-off from low-intensity agriculture/rural/urban activities - stormwater outlets with potential sewage contamination/combined stormwater outlet

Enterococci concentrations at this site are affected by rainfall. Cass Bay

Year n 95%ile MAC SIC SFRG 2002/2003 65 155 B Moderate Good 2003/2004 62 336 C Moderate Fair 2004/2005 59 379.5 C Moderate Fair 2005/2006 63 438.5 C Moderate Fair 2006/2007 65 427.5 C Moderate Fair 2007/2008 65 280 C Moderate Fair 2008/2009 70 64 B Moderate Good


• Stream discharging close to the recreational area with the stream potentially affected by: - stormwater outlets with potential sewage contamination/combined stormwater outlet - run-off from low-intensity agriculture/rural/urban activities



Rapaki Bay Year n 95%ile MAC SIC SFRG

2002/2003 72 203 C Moderate Fair 2003/2004 73 127 B Moderate Good 2004/2005 71 129 B Moderate Good 2005/2006 69 181.5 B Moderate Good 2006/2007 67 137.5 B Moderate Good 2007/2008 69 132.5 B Moderate Good 2008/2009 71 129 B Moderate Good



Governors Bay

Year n 95%ile MAC SIC SFRG 2002/2003 71 332 C Moderate Fair 2003/2004 76 420 C Moderate Fair 2004/2005 76 1000 D Moderate Poor 2005/2006 73 1000 D Moderate Poor 2006/2007 70 1000 D Moderate Poor 2007/2008 69 297 C Moderate Fair 2008/2009 71 253 C Moderate Fair



Enterococci concentrations at this site are affected by rainfall. Charteris Bay

Year n 95%ile MAC SIC SFRG 2002/2003 67 75 B Low Good 2003/2004 69 97.5 B Low Good 2004/2005 69 97.5 B Low Good 2005/2006 66 125.6 B Low Good 2006/2007 67 285.5 C Low Fair 2007/2008 68 152 B Low Good 2008/2009 68 111.5 B Low Good





Church Bay Year n 95%ile MAC SIC SFRG

2002/2003 63 91 B Low Good 2003/2004 66 160.8 B Moderate Good 2004/2005 62 124.4 B Moderate Good 2005/2006 65 122 B Moderate Good 2006/2007 67 119.6 B Moderate Good 2007/2008 68 112 B Moderate Good 2008/2009 71 111 B Moderate Good



Diamond Harbour Bay

Year n 95%ile MAC SIC SFRG 2002/2003 72 619 D Moderate Poor 2003/2004 73 762 D Moderate Poor 2004/2005 69 365.5 C Moderate Fair 2005/2006 68 393 C Moderate Fair 2006/2007 68 393 C Moderate Fair 2007/2008 69 367.5 C Moderate Fair 2008/2009 73 83.9 B Moderate Good



Enterococci concentrations at this site are affected by rainfall. Purau Bay

Year n 95%ile MAC SIC SFRG 2002/2003 58 206 C Moderate Fair 2003/2004 61 188 B Moderate Good 2004/2005 60 190 B Moderate Good 2005/2006 67 313 C Moderate Fair 2006/2007 68 312 C Moderate Fair 2007/.2008 68 312 C Moderate Fair 2008/2009 72 303 C Moderate Fair



Enterococci concentrations at this site are affected by rainfall.



Appendix 14: Relationship between DO %saturation and water temperature in harbour water

R2 = 0.6475

60

70

80

90

100

110

120

0 5 10 15 20 25

Water temperature °C

DO

% s

atur

atio

n

factors influencing whakaraup - whaka-ora healthy...

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