Jane Brook is an ephemeral waterway in a largely natural state, with much of its riparian zone in the

upper catchment still vegetated. It drains the Darling Scarp before flowing through the coastal plain and into the upper Swan Estuary upstream of Whiteman Bridge. Strelley Brook, a small tributary of Jane Brook, flows through the largely cleared coastal plain portion of the catchment and into Jane Brook just upstream of the confluence with the Swan.

Soils in the catchment range from lateritic and ironstone gravels in the upper reaches to the east, to red and yellow earths on the western plains. Groundwater tends to have a relatively minor contribution to flow in Jane Brook.

Agriculture is the dominant land use in the catchment. Viticulture and poultry farming are the principal land uses in the lower Jane Brook catchment, while the upper catchment supports pasture. Little native vegetation remains in the lower catchment below the Darling Scarp, which includes expanding areas of intensive housing developments. Large tracts of natural bushland remain in the steep middle catchment along the scarp, including a portion of the John Forrest National Park. The upper catchment above the scarp is rural and urban with patchy areas of bushland remaining. Much of the brook’s fringing vegetation remains intact.

Water quality is monitored at the Department of Water gauging station near the catchment’s lower end, shortly before the brook flows into the upper Swan Estuary. This site is positioned to indicate what nutrients are leaving the catchment and entering the Swan River, so the data may not represent nutrient concentrations in upstream areas.

Length ~ 17.8 kmAverage rainfall ~ 800 mm per yearGauging station near monitored site

Site number 616088

Catchment area 137 km2 (total)135 km2 (monitored)

River flow Ephemeral (June to December)No major water supply dams in catchment

Average annual flow ~ 9.4 GL per year (2007–11 average)Percentage of average inflow to Swan River

~ 4.9% of total inflow per year (of monitored catchments with flow data)

Main land uses Broad acre grazing, viticulture, horticulture, remnant vegetation and expanding urban areas

Jane Brook – facts and figures

Year 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011Annual flow (GL) 7.8 14.1 8.1 9.0 10.2 1.1* 17.4TN median (mg/L) 0.70 0.43 0.44 0.53 0.51 0.72 0.66 0.54 0.64 0.56 0.63 0.43 0.86TP median (mg/L) 0.016 0.017 0.019 0.021 0.025 0.016 0.024 0.009 0.017 0.017 0.021 0.011 0.032TN load (t/yr) 6.90 12.64 7.06 7.82 9.17 0.72* 16.17TP load (t/yr) 0.11 0.22 0.12 0.12 0.16 0.01* 0.30

Nutrient Summary: concentrations, loads and HRAP targets

TN short term target = 2.0 mg/L TN long term target = 1.0 mg/L TP short term target = 0.2 mg/L TP long term target = 0.1 mg/L

insufficient data to test target failing both short and long-term target passing short but failing long-term target passing both short and long-term target

0 1 2 3 40.5Kilometres

A small rock weir on Jane Brook

Photo: Dieter Tracey

* best estimate using available data. # Statistical tests that account for the number of samples and large data variability are used for testing against targets on three years of winter data. Thus the annual median value can be above the target even when the site passes the target (or below the target when the site fails).

Jane Brook

Swan Canning catchmentNutrient report 2011

John Forrest National Park

Legend

Animal keeping, non-farming

Offices, commercial & education

Waterways & drains

Farm

Horticulture & plantationIndustry & manufacturing

Lifestyle block / hobby farm

Quarry

Recreation

Conservation & naturalResidential

Sewerage

Transport

Unused, cleared bare soilViticulture

Monitored site

Department of Water

Photo: Water Science Branch

Photo: Water Science Branch

Changes in nutrient concentrations over time in Jane Brook

Nutrient fractions and loads in Jane Brook

TN C

once

ntra

tion

(mg/

L)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

99 00 01 02 03 04 05 06 07 08 09 10 11 12

TP C

once

ntra

tion

(mg/

L)

0.00

0.05

0.10

0.15

0.20

99 00 01 02 03 04 05 06 07 08 09 10 11 12

Trend:

While it appears that total nitrogen (TN) concentrations have been stable over the reporting period, trend analysis detected an emerging decreasing trend of 0.019 mg/L/yr over the long-term (2002–11) and a decreasing trend of 0.15 mg/L/yr over the short-term (2007–11). There is no obvious reason for these trends.

HRAP Target: Jane Brook has been passing both the short- and long-term TN targets since monitoring began.

Total nitrogen concentrations over the 1999 to 2011 monitoring period Total phosphorus concentrations over the 1999 to 2011 monitoring period

Just over half of the nitrogen (N) in Jane Brook is present as dissolved inorganic N (DIN, consisting of ammonium – NH4

+ and N oxides – NOx). These forms of N are readily available for plant and algal growth. The remaining N is present as organic N which is made up of dissolved organic N (DON)and particulate N (PON).

Average composition of nitrogen (N) in Jane Brook over the 2007 to 2011 monitoring period

DON largely comprises organic compounds leached from peaty subsoils and degrading plant and animal matter and is available for uptake by plants, algae and bacteria. PON is composed of plant and animal debris and needs to be further broken down to become available to plants and algae.

Of the 14 catchments with flow data, Jane Brook contributed the seventh-largest average TN load (2007–11) to the Swan-Canning estuary. Note that unlike the other catchments with flow data, Jane Brook had no flow data for 2009.

Average composition of phosphorus (P) in Jane Brook over the 2007 to 2011 monitoring period

Almost two-thirds of the phosphorus (P) is present as particulate P, commonly associated with soil erosion and suspended sediments in the water column. Plants and algae do not readily absorb particulate P, however some of it will become available over time as particles decompose or release bound phosphate. The remainder of the P is present as highly bioavailable soluble reactive phosphorus (SRP). Likely sources of SRP include animal waste and fertiliser. SRP is readily used by plants and algae.

Jane Brook contributed the third-smallest average TP load (2007–11) of the 14

catchments with flow data. It also contributed the smallest TP load in terms of load per unit area. Note that unlike the other catchments with flow data, Jane Brook had no flow data for 2009.

DON40%

NH4+

5%

NOx

46%

PON9%

SRP39%

Particulate P61%

PhosphorusNitrogen

Nitrogen Phosphorus

Trend:

Total phosphorus (TP) concentrations do not appear to have changed over the reporting period. However statistical analysis detected an emerging decreasing trend of 0.001 mg/L/yr over the long-term (2002–11) and no trend over the short-term. As yet not enough statistically independent samples are available to verify the emerging long-term trend.

HRAP Target: Jane Brook has been passing both the short- and long-term TP target since monitoring began.

A meandering section of Jane Brook with little riparian vegetation present. Photo: Water Science Branch.

Jane Brook: Nutrient report 2011

Med

ian

P Co

ncen

trat

ion

(mg/

L)

Med

ian

Dis

char

ge (M

L)

TPSRPParticulate PFlow

0

500

1000

1500

2000

2500

3000

3500

0.00

0.04

0.08

0.12

0.16

0.20

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Med

ian

N C

once

ntra

tion

(mg/

L)

Med

ian

Dis

char

ge (M

L)

TNDONNH4+

NOx

FlowPON

0

500

1000

1500

2000

2500

3000

3500

0.0

1.0

2.0

3.0

4.0

5.0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Seasonal variation in nutrient concentrations in Jane Brook

Nitrogen

A seasonal pattern in TN and NOx concentrations is apparent from the 2007 to 2011 monitoring data. TN and NOx concentrations peaked early in winter, corresponding with increased flow. The direct relationship between concentration and flow suggests that much of the N is entering the brook via surface and subsurface flows. NOx concentrations decreased from July until November when concentrations were

negligible. The organic N and NH4

+ concentrations in Jane Brook remained fairly constant throughout the year.

Nitrogen seasonal variation over the 2007 to 2011 monitoring period Phosphorus seasonal variation over the 2007 to 2011 monitoring period

Phosphorus

A slight seasonal pattern is apparent in the 2007 to 2011 monitoring data. TP and particulate P concentrations were highest in winter (July to August), corresponding with the increase in flow. The relationship between TP concentrations and flow suggests that surface and subsurface flow play an important role in transporting P to the brook. SRP concentrations in Jane Brook were mostly constant throughout the year, with a slight increase during

winter. The high SRP and TP readings in May were due to 2008 winter rains starting early, transporting P to the brook.

Photographs of Jane Brook: (Top left) Looking downstream at the Jane Brook sampling site. (Bottom left) National Park Falls in John Forrest National Park. (Right) Abundant Watsonia in the understorey of the vegetation lining Jane Brook.

Photo: Lynette GalvinPhoto: Dieter Tracey

Photo: Dominic Heald

Jane Brook: Nutrient report 2011

Photo: Water Science Branch Photo: Water Science Branch

Summary: Jane Brook

Local nutrient reduction strategies for Jane Brook

• Jane Brook is passing both the short- and long-term TN and TP targets.

• It has one of the lowest median TN and TP concentrations of the 15 priority catchments.

• A short-term decreasing trend in TN concentrations was detected, as well as emerging decreasing long-term TN and TP trends.

• Of the 15 priority catchments, Jane Brook has the third-highest proportion of N present as bioavailable DIN, a large portion of which is NOx (oxidised N).

Swan Canning water quality improvement planThe Swan Canning water quality improvement plan (SCWQIP) complements the HRAP and presents a roadmap for reducing nutrient inputs into the river systems. It uses sophisticated modelling to identify nutrient sources and provides nutrient-reduction targets for each of the subcatchments.

Nutrient reduction strategies being undertaken or recently completed in the Jane Brook catchment include:

• A draft catchment management plan. The existing Swan-Mundaring integrated catchment management plan is comprehensive but more than 10 years old and natural resource management has changed considerably since its development. The new Eastern catchment management plan (which includes individual catchment action plans) will be finalised in 2012.

• The Jane Brook Catchment Group’s efforts to raise awareness in all sectors of the community on the importance of protecting remnant vegetation, revegetating and rehabilitating bushland, restoring streams and creeklines and working in partnership with government, industry and community groups.

• The Eastern Hills Tributaries Project: this has been funded by the Perth Region Natural Resource Management group through the federal government’s Caring for our Country program for foreshore restoration activities on key tributaries to the Swan-Canning estuary including the Jane Brook catchment. Erosion-prone sites are the focus.

• Eastern Hills Catchment Management Program this is a partnership project whereby the Eastern Metropolitan Regional Council is working together with the Swan River Trust, local governments and community groups to deliver water quality and community capacity-building outcomes.

• The Phosphorus Awareness Project which aims to assist the community in reducing their

Healthy Rivers action planThe Healthy Rivers action plan (HRAP) aims to protect the environmental health and community benefit of the Swan-Canning river system by improving water quality. This is achieved through a ‘catchment to coast’ approach.

nutrient outputs through education, promotion and behaviour change programs.

www.water.wa.gov.auFor further information please contact the Water Science Branch, Department of Watercatchmentnutrients@water.wa.gov.au

ISBN 978-1-922124-61-6

Photo: Water Science Branch

For further information on the HRAP and the SCWQIP contact info@swanrivertrust.wa.gov.au

Max. load (t/yr) Conc. target (mg/L) % reductionTN 11.0 0.75 0%TP 0.58 0.075 0%

SCWQIP load and concentration targets for Jane Brook