haw river sediment quality assessment july 2011

i

U.S. Fish and Wildlife Service U.S. Geological Survey

Ecological Services Columbia Environmental Research Center

Raleigh, North Carolina Columbia, Missouri

Haw River Sediment Quality Assessment

July 2011

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Preface

The U.S. Fish and Wildlife Service coordinated an assessment of the chemical contaminants in,

and toxicity of, sediments within the impounded reaches upstream of dams on the Haw River,

North Carolina. The work was coordinated by Tom Augspurger (Ecologist / Environmental

Contaminant Specialist) and Sara Ward (Ecologist / Environmental Contaminant Specialist) in

the U.S. Fish and Wildlife Service’s Raleigh Field Office and was funded by the U.S. Fish and

Wildlife Service’s Division of Environmental Quality (study identifiers 4F41 and 200840001.1).

Toxicity tests were performed by the U.S. Geological Survey’s Columbia Environmental

Research Center (CERC) under the direction of Chris Ingersoll through an intra-agency

agreement with the U.S. Fish and Wildlife Service. Other CERC scientists primarily responsible

for the toxicity testing component of the project were Nile Kemble and James Kunz. Adam

Riggsbee of RiverBank Ecosystems (formerly with Restoration Systems, LLC) assisted with

sample site selection during a field reconnaissance. Katherine Irvine with the North Carolina

Wildlife Resources Commission assisted with sample collection. Analytical chemistry was

performed by Environmental Conservation Laboratories, Inc. This final report follows a 2009

summary of methods and results.

Additional questions, comments, and suggestions related to this report are encouraged. Inquires

can be directed to the U.S. Fish and Wildlife Service at the following address:

Tom Augspurger

U.S. Fish and Wildlife Service

P.O. Box 33726

Raleigh, North Carolina 27636-3726

[email protected]

Suggested citation: U.S. Fish and Wildlife Service. 2011. Haw River Sediment Quality

Assessment. U.S. Fish and Wildlife Service, Ecological Services, Raleigh, NC.

Cover: Saxapahaw Dam, Haw River, North Carolina

Keywords: Haw River, North Carolina, sediments, 4F41, 200840001.1, NC-2, NC-4, NC-6

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Abstract

This report documents an evaluation of chemical contaminants in, and toxicity of, sediments

collected from impoundments created by dams on the Haw River in Alamance and Chatham

Counties, central North Carolina. Eighteen whole-sediment samples from within the impounded

reaches of Swepsonville Dam, Saxapahaw Dam, Bynum Dam, and B. Everett Jordan Dam were

collected in June 2008. All samples were analyzed for elemental contaminants and polycyclic

aromatic hydrocarbons. All samples were also assessed with a battery of toxicity tests.

Elemental contaminant concentrations in whole-sediments were below those of toxicological

significance. One or more sediment PAHs with freshwater sediment threshold effects screening

values exceeded the screening values at 17 of the 18 sites, but no samples exceeded the probable

effects concentrations. Survival of Hyallela azteca (freshwater amphipod) exposed to sediments

from one of five sites in the Bynum Dam impounded reach was 80% and statistically lower than

controls in 28-d toxicity tests; amphipod growth was not affected at this or any other site. Whole-

sediments had no significant effect on survival or growth in 10-d tests with Chironomus dilutus

(freshwater midge) at any of the 18 sites. Results indicate the contaminants associated with the

whole-sediment samples were not chronically toxic to amphipods or midge. In 2-d sediment

elutriate (water-extractable fraction) tests with Ceriodaphnia dubia (freshwater cladoceran),

statistically-significant reductions in survival occurred in four of the 18 exposures (two from the

five samples taken from within the Bynum Dam impounded reach, one from the flooded portion

of Big Alamance Creek, and one in the headwaters of Jordan Lake). Chromium in pore water at

one of five sites in the Saxapahaw Dam impoundment was 119 μg/L; the State standard for

chromium is 50 μg/L. Copper, lead, and zinc in the elutriate and pore water samples exceeded

State standards infrequently but most commonly in sediments from the Saxapahaw Dam

impoundment. This is an indication that aggressive re-suspension of sediments like those tested

could temporarily impair surface water quality. These data and surveys of sediment physical

characteristics, volume, and likelihood of movement can be used together to infer the impacts the

different types of sediments disturbing activities on short-term water column chemistry. In

particular, data regarding the modeled or measured sediment re-suspension caused by specific

sediment disturbing activities (e.g., dredging, dam alterations, dam removal, etc.) will help put

the elutriate test results in context for a range of sediment management practices.

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CONTENTS

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

RESULTS / DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

MANAGEMENT RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

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TABLES Page

1. Haw River sediment sampling location data and the date and time of collection 3

2. Total organic carbon, grain size and moisture measured in whole-sediment samples 14

collected from the Haw River

3. Elemental contaminants in whole-sediment samples collected from the Haw 15

River. For each element, results are compared to threshold-effects concentration

guidelines of MacDonald et al. (2000)

4. Polycyclic aromatic hydrocarbons measured in whole-sediment samples collected 16

from the Haw River. For each compound, results are compared to threshold-effects

concentrations of MacDonald et al. (2000)

5. Response of Hyalella azteca in 28-d whole-sediment exposures, Chironomus dilutus

in 10-d whole-sediment exposures, and Ceriodaphnia dubia in 2-d elutriate exposures

prepared from sediment samples collected from the Haw River 17

6. Water quality characteristics in 2-d elutriate exposures with Ceriodaphnia dubia

prepared from Haw River sediment samples and a control sediment 18

7. Elemental contaminant concentrations of 2-d elutriate exposures with Ceriodaphnia

dubia prepared from Haw River sediment samples and a control sediment 19

8. Water quality characteristics of pore water isolated from Haw River whole-

sediment samples 20

9. Elemental contaminant concentrations of pore water isolated from Haw River

whole-sediment samples 21

10. Mean water quality characteristics of overlying water in whole-sediment toxicity

tests with Hyalella azteca and Haw River sediments 22

11. Mean water quality characteristics of overlying water in whole-sediment toxicity

tests with Chironomus dilutus and Haw River sediments 23

12. Haw River sediment elutriate and pore water exceedences of North Carolina water

quality standards or action levels for elemental contaminants 24

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FIGURES Page

1. Vicinity map for Haw River dam sediment sampling sites 4

2. Haw River sediment sampling sites upstream of Swepsonville Dam 5

3. Haw River sediment sampling sites upstream of Saxapahaw Dam 6

4. Haw River sediment sampling sites upstream of Bynum Dam 7

5. Haw River sediment sampling sites downstream of Bynum Dam 8

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Introduction

This report documents an evaluation of chemical contaminants in, and toxicity of, sediments

collected from impoundments created by dams on the Haw River, in central North Carolina. The

Haw River originates in the Northern Inner Piedmont ecoregion in Guilford County and drains

1,526 square miles (NCDWQ 1999) over its 110 miles before entering the Cape Fear River. The

Haw River has been dammed many times to provide power for mills, irrigation, and drinking

water. Those societal benefits can have ecological costs; impoundments were one of the three

most frequently cited stressors as limiting factors for survival and recovery of freshwater fauna

in a survey of experts for fishes, amphibians, mussels, crayfishes, and insects (Richter et al.

1997). Neves et al. (1997) and Watters (2000) reviewed the specific effects of impoundments on

freshwater mollusks, noting flow changes, population fragmentation, water quality problems and

sediment issues. Dams also alter nutrient dynamics of riverine systems (Freeman et al 2003) and

can degrade water quality within the impounded reach and downstream (Arnwine et al. 2006).

Dam removals can be conducted with high environmental gains and low impacts if structural,

operational, and seasonal controls to manage sediment transport are applied (Riggsbee 2006).

Removal of dams has re-established important anadromous fish runs in North Carolina and has

restored habitat and improved water quality for a variety of other lotic species. Experience with

the regulatory aspects of dam removal has evidenced concern over mobilization of sediments

accumulated behind dams upon their removal. Sediments can accumulate contaminants, and at

high concentrations those contaminants can be an in-place concern as well as a concern upon

downstream mobilization. Resolving these issues is not easy; there is no consistent approach for

evaluating sediments at dam removal sites, and dam owners are reluctant to conduct expensive

testing without a certain regulatory framework. Also, the lack of a specific regulatory

framework hampers efforts to manage analytical costs.

The U.S. Fish and Wildlife Service (Service) has worked with many partners to evaluate the

significance of sediment contamination at dam sites (Augspurger and Cantrell 2004, Augspurger

et al. 2007). Objective sediment characterizations inform sediment management planning, one

of the essential components of a dam removal. In 2008, we initiated this study to provide an

assessment of sediment contamination at three dams on the Haw River in Alamance and

Chatham Counties that have been identified for potential removal by conservation groups and

agencies: Swepsonville Dam, Saxapahaw Dam, and Bynum Dam. The Service and partners’

objectives of the effort were to:

1) generate current data on the chemical and physical quality of the sediments behind the

dams for comparison to sediment toxicological screening values; and,

2) assess the toxicity of whole sediments and sediment elutriates prepared from these

whole-sediment samples to sensitive aquatic organisms.

The following summary presents the sediment sampling and testing methods, results, and an

interpretation of the findings.

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Methods

Sample sites

Factors considered in determining the number and location of samples included the location of

identified potential sources of concern and areas of sediment accumulation. Physical factors

considered included the area and depth of potentially affected sediments behind the dams,

distribution of sediments, and the length and breadth of the impounded reaches.

During reconnaissance of the river, a hydrogeologist with Restoration Systems, LLC

qualitatively surveyed the patterns and relative magnitudes of sediment deposition. Field

surveys were conducted in a small boat with a calibrated fathometer (or “depth finder”) to gage

the overall pattern of deposition by locating depositional features. Once sediment accumulations

were located, a graduated stadia rod with a metal tip was used to measure depth of refusal and to

qualitatively assess sediment composition (i.e., sand, silt, clay). Sediment accumulations with

fine grain composition were sampled using a petite Ponar dredge for verification (Restoration

Systems, LLC, 2008). Corresponding waypoints were recorded using a mapping grade GPS unit

so they could be re-located for sampling.

Sand and gravel, while the most commonly encountered sediment, have little potential for

contaminant accumulation. Areas of fine-grained sediment accumulation were targeted for

sample collection because they have the greatest potential to accumulate contaminants.

Eighteen samples were collected by a Service Ecologist / Environmental Contaminants Specialist

with e assistance of a technician with the North Carolina Wildlife Resources Commission.

Samples were collected between June 25 and 28, 2008. Table 1 lists the collection locations,

collection date, time, and specific coordinates. Figures 1 through 5 depict collection locations.

Sediment sample collection and storage

Samples were collected, transported, stored, and shipped for analyses under chain of custody.

A stainless-steel petit Ponar dredge was used to collect the top 5 to 10 cm of sediment; multiple

grabs were collected and composited to form one sample at each site. The composite of the grab

samples was homogenized by stirring with a stainless-steel spoon in a stainless-steel bucket.

Debris (e.g., sticks, leaves, rocks bigger than about 0.5 cm3) were physically removed during

homogenization. Collection equipment was thoroughly cleaned (ambient water rinse, detergent

and water scrub, distilled / demineralized water rinse, 10% nitric acid rinse, another distilled /

demineralized water rinse, acetone rinse, and a final rinse with distilled / demineralized water)

before sampling at each site.

Aliquants of the homogenate were split in into chemically cleaned glass jars (provided by the

analytical laboratory) with Teflon®-lined lids for chemical analyses with about 8 L of the same

sediment homogenate from each site placed in two high-density polyethylene jars (EP Scientific

Products, Miami, OK) for toxicity testing. Samples were stored in a cooler on ice (about 4oC) in

the field. Upon reaching the Service lab in Raleigh each evening, samples were stored

refrigerated (about 4oC).

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Table 1. Haw River sediment sampling location data and the date and time of collection.

Sample ID River

Mile

Description and GPS Coordinates

H 1

14.2

Upstream of Bynum Dam, N 35.77778˚, W -79.14906˚ (06-25-08; 09:45 am)

H 2 14.3 Upstream of Bynum Dam, N 35.77822˚, W -79.15084˚ (06-25-08; 10:05 am)

H 3 14.2 Upstream of Bynum Dam, N 35.77708˚, W -79.15064˚ (06-25-08; 12:25 pm)

H 4 14.1

Upstream of Bynum Dam, N 35.77648˚, W -79.14922˚ (06-25-08; 12:42 pm)

H 5 14.1 Upstream of Bynum Dam, tip of island just upstream of dam,

N 35.77613˚, W -79.14842˚ (06-25-08; 2:55 pm)

H 6 36.9 Upstream of Swepsonville Dam, N 36.01054˚, W -79.36382˚

(06-26-08; 5:40 pm)

H 7 37.2 Upstream of Swepsonville Dam, right bank just downstream from Alamance

Creek, N 36.01493˚, W -79.36555˚ (06-26-08; 5:55 pm)

H 8 33.1 Upstream of Saxapahaw Dam, N 35.96228˚, W -79.33485˚ (06-27-08; 8:45 am)




H 12 32.0 Upstream of Saxapahaw Dam, N 35.94831˚, W -79.32717˚ (06-27-08; 12:25 pm)

H13 36.7 Upstream of Swepsonville Dam, just upstream of the mouth of the small

divergence leading to the powerhouse, N 36.00849˚, W -79.36210˚

(06-27-08; 2:15 pm)

H 14

H15

H16

H 17

H18

36.8

37.4

37.4

8.5

7.9

Upstream of Swepsonville Dam, approximately 50’ upstream of H13,

N 36.00872˚, W -79.36225˚ (06-27-08; 2:30 pm)

Upstream of Swepsonville Dam, in flooded portion of Big Alamance Creek,

N 36.01741˚, W -79.37690˚ (06-27-08; 4:00 pm)

Upstream of Swepsonville Dam, in flooded portion of Big Alamance Creek,

N 36.01797˚, W -79.37064˚ (06-27-08; 4:40 pm)

Downstream of Bynum Dam, in headwaters of Jordan Lake, at tip of

depositional island, N 35.71328˚, W -79.09017˚ (06-28-08; 6:15 pm)

Downstream of Bynum Dam, in headwaters of Jordan Lake,

N 35.70527˚, W -79.08618˚ (06-28-08; 5:10 pm)

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Figure 1. Vicinity map for Haw River impoundment sediment sampling sites. Samples sites

associated with each impounded reach are enlarged on subsequent maps.

1

Figure 2. Haw River sediment sampling sites upstream of Swepsonville Dam. 5

1

Figure 3. Haw River sediment sampling sites upstream of Saxapahaw Dam

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2

Figure 4. Haw River sediment sampling sites upstream of Bynum Dam

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Sediment chemical and physical analyses

Sediment samples were delivered to Environmental Conservation Laboratories, Inc. (ENCO) in

Cary, NC on June 26 and 30, 2008. ENCO has the North Carolina Laboratory Certification for

the requested analyses. Elemental contaminants and PAHs include many common pollutants

and were targeted for analyses in all samples. Additionally, these compounds have consensus-

based freshwater effects sediment quality guidelines (MacDonald et al. 2000, USEPA 2000b)

with which to evaluate the results.

Figure 5. Haw River sediment sampling sites downstream of Bynum Dam, in headwaters of Jordan

Lake.

8

9

Sediment samples were analyzed for Al, As, Cd, Cr, Cu, Fe, Pb, Mn, Ni, and Zn by USEPA

method 6010B (inductively coupled plasma-atomic emission spectrometry, or ICP-AES).

Analyses of mercury in sediment samples were by USEPA method 7471A (cold-vapor

atomic absorption spectrophotometry). ENCO analyzed sediments for PAHs, including 1-

methylnaphthalene, 2-methylnaphthalene, acenaphthene, acenaphthylene, anthracene,

benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene,

benzo(k)fluoranthene, chrysene, dibenzo(a,h)anthracene, fluoranthene, fluorine,

indeno(1,2,3-cd)pyrene, naphthalene, phenanthrene and pyrene, by USEPA method 8270C

(gas chromatography / mass spectrometry, or GC/MS).

Pore-water and elutriate samples were prepared from sediments by U.S. Geological Survey

Columbia Environmental Research Center (CERC), Columbia, MO (preparations described

below). These were also analyzed for elemental contaminants by ENCO. Elements in the

analyses included Al, As, Cd, Cr, Cu, Fe, Pb, Mn, Ni, and Zn by USEPA method 200.8

(Trace Elements by ICP/Mass Spectrometry). This method was also used to measure Mg and

Ca which provided the measures of hardness for these samples (by the calculation method in

Standard Methods SM 2340B).

Physical characterization of whole sediments included percentage water, particle size and

total organic carbon (TOC). Particle size analysis was conducted at CERC by sieve series

following methods described in Foth et al. (1982), Gee and Bauder (1986), and Kemble et al.

(1994). The TOC analyses were by the Walkley Black method (Schumacher 2002) and were

conducted by Test America of Tampa, FL (under subcontract to ENCO).

All analyses were accompanied by batch-specific quality control / quality assurance samples

(blanks, spikes, and duplicates). Review of quality assurance data indicates acceptable

precision and accuracy for all analyses. There was poor repeatability in spiked /duplicate

sample recoveries for total organic carbon, Al, Fe and Mn in sediment, but this was the result

of low spike level relative to high concentration of these constituents in sediment. Results of

duplicate sample analyses were within specifications. Some laboratory blank samples

contained low levels of As and Zn, but blank concentrations were < 0.1 mg/kg dry weight,

far less than the concentrations of these analytes in sediments and therefore of no concern in

data interpretation.

Threshold effects concentrations (TECs) and probable effects concentrations (PECs) were

used to assess the significance of sediment chemistry results. The TECs are concentrations

of contaminants in sediment below which adverse effects to sensitive aquatic organisms are

not expected to occur, and the PECs are effect-based sediment quality guidelines established

as concentrations of contaminants in sediment above which adverse effects are expected to

frequently occur in field-collected sediments (MacDonald et al. 2000).

Sediment toxicity tests

Samples were sent to the CERC by overnight delivery on June 30, 2008. Toxicity tests

included 28-d whole-sediment exposures of Hyallela azteca (freshwater amphipod)

10

evaluating effects on growth and survival, 10-d whole-sediment exposures of Chironomus

dilutus (freshwater midge) evaluating effects on growth and survival (USEPA 2000a, ASTM

2007), and 2-d sediment elutriate (water-extractable fraction of the sediment) exposures of

Ceriodaphnia dubia (freshwater cladoceran) evaluating effects on survival (USEPA 1993a).

This battery of toxicity tests was selected to help evaluate the toxicity of sediments, both in-

place and upon re-suspension.

Test organism culture - Amphipods were mass cultured at 23oC with a luminance of about

800 lux using 80-L glass aquaria containing 50 L of well water (hardness 283 mg/L as

CaCO3, alkalinity 255 mg/L as CaCO3, pH 7.8; Ingersoll et al. 2002). Amphipods used to

start the tests were obtained by collecting amphipods that passed through a #35 U.S. Standard

size (500-µm opening) and were collected on a #40 (425-um opening) sieve placed under

water. Amphipods were held in 3 L of water with gentle aeration and with a small amount of

Tetramin® and a maple leaf for 24 hours before the start of the test.

Midge were mass cultured under static conditions in 5.7-L polyethylene cylindrical chambers

containing about 3 L of water and 25 ml of silica sand as a substrate at a temperature of 25oC

and a light intensity of about 800 lux. Second instar midge (10-d old) to start the tests were

obtained by isolating <24 h old midge larvae ten days before starting the toxicity test.

Cladocerans where cultured under static conditions in 30-ml disposable clear plastic cups

each containing 15 ml of well water and one adult at a temperature of 25oC and a light

intensity of about 200 lux (USEPA 1993a). Cladocerans in each cup were fed 0.1 ml/d Yeast-

Cerophyll-trout chow (YCT; 1.7 to 1.9 g/L) and 0.1 ml/d unicellular green algae (3 x 107

cells of Selenastrum capricornutum). Neonates (<24 hours) to start the tests were obtained

from adults that produce eight or more young in their third brood or subsequent broods.

Whole-sediment toxicity tests - Whole-sediment toxicity tests with H. azteca were conducted

for 28 d and with C. dilutus were conducted for 10 d in accordance with methods described

in ASTM (2007) and USEPA (2000a) starting within 3 weeks of sediment collection.

Endpoints measured in the amphipod exposures included survival and length on Day 28.

Endpoints measured in the midge exposures included survival and growth (ash-free dry

weight) on Day 10. Test sediments were homogenized in a stainless-steel bowl using a

plastic spoon and added to exposure beakers 1 d before test organisms were added (Day -1).

Sub-samples of sediment were then collected for physical characterizations and for isolating

pore water. Amphipods and midge were exposed to 100 ml of sediment with 175 ml of

overlying water in 300-ml beakers with four replicates/treatment. The photoperiod was 16 h

light: 8 h dark at a light intensity of about 200 lux at the surface of the exposure beakers and

the temperature was 23oC. Each beaker received 2-volume additions/d of overlying water

starting on Day -1 (Ingersoll et al. 2002). Overlying water was prepared by diluting well

water with deionized water to a hardness of 100 mg/L as CaCO3, alkalinity of 85 mg/L as

CaCO3, and pH about 7.8. The water delivery system cycled every 4 h with each cycle

delivering 125 ml of water to each beaker. Tests were started on Day 0 by placing 10

amphipods or 10 midge into each beaker using an eyedropper. Amphipods in each beaker

were fed 1.0 ml of YCT (1.7 to 1.9 g/L) in a water suspension daily (USEPA 2000a, ASTM

11

2007). Midge in each beaker were fed 1.5 ml of Zeigler prime tropical flake fish food (red)

(Zeigler Bros, Inc., Gardens, PA) (6.0 mg of dry solids) in a water suspension daily (USEPA

2000a, ASTM 2007). Beakers were observed daily for the presence of animals, signs of

animal activity (i.e., burrowing), and to monitor test conditions (mainly water clarity).

Midge were isolated from each beaker on Day 10 of the exposure and amphipods were

isolated from each beaker on Day 28 of the exposure by pouring off most of the overlying

water, gently swirling the remaining overlying water and upper layer of sediment, and

washing the sediment through a No. 50 (300-µm opening) U.S. Standard stainless-steel sieve.

The materials that were retained on the sieve were washed into a glass pan and the surviving

midge and amphipods were removed. This process was repeated with the remainder of the

sediment in a beaker if all 10 of the amphipods or midge were not recovered from the upper

layer of the sediment. Amphipods from each sediment were counted and preserved in 8%

sugar formalin for subsequent length measurements (Ingersoll et al. 2002). Length of

amphipods was measured along the dorsal surface from the base of the first antenna to the tip

of the third uropod along the curve of the dorsal surface. Amphipod length measurements

were made using an EPIX imaging system (PIXCI® SV4 imaging board and XCAP

software; EPIX Inc., Buffalo Grove, IL) connected to a computer and a microscope (Ingersoll

et al. 2002). Midge from each sediment were counted and dried at 100oC in a drying oven

for subsequent ash-free dry weight measurements (ASTM 2007). Ash-free dry weight was

obtained by recording the weights after drying, transferring to an ashing oven and ashing at

500oC. Ash-free dry weights were determined by subtracting the ashed weight from the dry

weight.

About 50 ml of pore water was isolated from sediment samples by centrifugation at 5200

rpm (7000 x G) for 15 min at 4oC (Kemble et al. 1994). Immediately after pore water was

isolated, dissolved oxygen, pH, alkalinity, temperature, conductivity, total ammonia, and

hardness were measured using methods outlined in Kemble et al. (1994).

In the amphipod test, conductivity, pH, alkalinity, hardness, dissolved oxygen, and total

ammonia were measured in overlying test water on Day 0 (the day amphipods were added to

the exposure beakers) and Day 28 of the exposure. Conductivity and dissolved oxygen, in

overlying water were also measured weekly. Temperature in the water baths containing the

exposure beakers was recorded daily.

In the midge test, conductivity, pH, alkalinity, hardness, dissolved oxygen, and total

ammonia were measured in overlying test water on Day 0 (the day midge were added to the

exposure beakers) and Day 10 of the exposure. Conductivity and dissolved oxygen in

overlying water were also measured weekly. Temperature in the water baths holding the

exposure beakers was monitored daily.

Elutriate toxicity tests - Toxicity tests with C. dubia were conducted for 2 d in accordance

with methods outlined in USEPA (1993a) starting within 5 weeks of sediment collection.

Elutriate samples were prepared by mixing one part sediment with four parts water (prepared

by diluting well water, the characteristics of which are described at page 9 above under Test

organism culture, with deionized water to a hardness of 100 mg/L as CaCO3, alkalinity of 85

12

mg/L as CaCO3, and pH about 7.8). Elutriate samples were prepared following procedures

outlined in USEPA (1993a). About 50 ml of sediment was placed into two 250-ml high-

density polypropylene centrifuge tubes and topped off with 200 ml of water. The tubes were

sealed and tumbled on a rolling mill for 30 min. The tubes were then be centrifuged for 15

min at 5200 rpm (7000 x G). The water was then decanted through a US Standard #50

stainless steel sieve (300-µm opening) into a 500-ml beaker. A sub-sample of the elutriate

samples was collected for water quality characterization, with the remaining sample used in

toxicity tests.

The cladoceran test was started on Day 0 with <24-h old C. dubia. A total of 10 cladocerans

were exposed to each elutriate sample and were exposed individually in 30-ml disposable

clear plastic cups containing 15 ml of 100% elutriate test solution. Trays holding the plastic

cups were covered with plastic sheets to prevent evaporation. Cladocerans were maintained

in a water bath at 25±1º C on a 16 h light: 8 h darkness photoperiod at a light intensity of

about 200 lux. Cladocerans were not fed during the exposures. On Day 2, survival of the

cladocerans was determined by pouring all the test water into a petri dish and using a light

table to facilitate counting the neonates. Two of the elutriate samples that were found to be

toxic to C. dubia (H16 and H17) were re-tested in a dilution series. The two samples were

prepared by the same procedures outlined above and a 50 % dilution series (elutriate sample

was prepared with the 100 mg/L hardness water, testing 100, 50, 25, 12.5, 6.25% elutriate)

and a dilution water control.

Conductivity, pH, alkalinity, hardness, dissolved oxygen, and total ammonia were measured

in elutriate test water on Day 0 (the day cladocerans were added to the exposure beakers).

Temperature in the water baths containing the exposure beakers was recorded daily.

Statistical analyses

Statistical analyses for the amphipod exposures were conducted using one-way analysis of

variance (ANOVA) at p = 0.05 for all endpoints except length which was analyzed using a

one-way nested ANOVA at p = 0.05 (amphipods nested within a beaker; Snedecor and

Cochran 1982). Before statistical analyses were performed, all data were tested for

normality. Variance among treatment means for both endpoints was heterogeneous,

therefore, a rank analysis of variance was performed and mean differences were determined

using a t-test on ranked means (at p = 0.05). A sample was designated as toxic when mean

survival or growth was significantly reduced relative to the control sediment. Statistical

analyses on toxicity tests were performed with Statistical Analysis System programs (SAS

2001).

13

Results and Discussion

Whole-sediment analytical chemistry

Total organic carbon in the samples averaged 2.5% and the average percent fines (sum of silt and

clay fraction) was 58% indicating depositional areas were located for the assessment (Table 2).

There are no North Carolina or federal sediment quality criteria, but Tables 3 and 4 compare the

elemental contaminants and PAHs in whole sediment to the TECs and PECs of McDonald et al.

(2000). Florida and Wisconsin recommend TECs and PECs for use as guidance in their

programs, including evaluation of dredged material and risk assessment of contaminated sites

(MacDonald et al. 2003). While no regulatory implications are inferred in our use of the TECs

and PECs, sediment quality guidelines like these have been found to offer good utility in site

assessment by various government and non-government organizations (Wenning et al. 2005).

For elemental contaminants, only chromium at site H8 (62.6 mg/kg dry weight) exceeded the

chromium threshold-effects concentration guidelines (43.4 mg/kg) of MacDonald et al. (2000).

All other metals were less than their corresponding TECs; because sample results less than these

values are not expected to produce adverse effects to sensitive aquatic organisms, they are

therefore considered toxicologically insignificant.

In the PAH analyses (Table 4), 1-methylnaphthalene (<4 ug/kg), 2-methylnaphthalene (<3

ug/kg), acenaphthene (<3 ug/kg), acenaphthylene (<3 ug/kg), fluorine (<3 ug/kg), and

naphthalene (<3 ug/kg) were less than corresponding detection limits in all samples. Anthracene

was measured above a 4 ug/kg detection limit in only one sample, H5 which contained 110

ug/kg. One or more sediment PAHs with freshwater sediment TECs were in excess of TECs at

every sampling station except H2. No samples exceeded the PECs. MacDonald et al. (2000)

and USEPA (2000b) concluded that infrequent exceedences of TECs is not associated with

sediment toxicity; however, exceedences of PECs (by frequency or by magnitude) is frequently

associated with sediment toxicity.

Toxicity tests

Control survival of amphipods, H. azteca, was 100% and met the test acceptability requirement

of 80% survival recommended in USEPA (2000a) and ASTM (2007). Amphipod survival in the

reference sediment was 93%. Control survival of the midge, C. dilutus was 80% and also met

the test acceptability requirement of 70% survival recommended in USEPA (2000a) and ASTM

(2007). Midge survival in the reference sediment was 96%. Survival of amphipods exposed to

sediments from site H2 was 80% (Table 5) and statistically lower than controls in 28-d toxicity

tests; amphipod growth was not affected at this or any other site. Whole sediments had no

significant effect on survival or growth in 10-d tests with midges (Table 5). Results indicate the

contaminants associated with the whole-sediment samples were not chronically toxic to

amphipods or midge. In 2-d sediment elutriate (water-extractable fraction) tests with C. dubia,

statistically-significant reductions in survival occurred in four (H1, 2, 16 and 17) of the 18

exposures (Table 5). Tables 6 through 11 summarize the chemistry of elutriates and overlying

water in the whole-sediment toxicity tests.

14

Table 2. Total organic carbon, grain size and moisture measured in whole-sediment samples

collected from the Haw River.

1TA = Test America, Tampa, FL

2CERC = USGS Columbia Environmental Research Center, Columbia, MO

3ENCO = Environmental Conservation Laboratories, Inc., Cary, NC

River

Mile

Sample

ID

Total

Organic

Carbon

(%) Sand (%) Clay (%) Silt (%) Moisture (%)

TA

1 CERC

2 CERC CERC ENCO

3

Sw

epso

nvil

le

37.4 H15 1.6 55 22 23 37.5

37.4 H16 2.0 39 20 40 44.7

37.2 H7 1.9 43 18 38 45.5

36.9 H6 1.8 52 22 26 44.2

36.8 H14 2.5 43 20 37 51.8

36.7 H13 1.6 60 19 21 44.0

Sax

apah

aw 33.1 H8 2.6 28 25 47 52.1

32.8 H9 2.4 34 21 45 41.8

32.2 H10 2.6 28 22 50 57.9

32.1 H11 1.4 54 17 28 37.7

32 H12 1.8 45 21 34 44.0

Bynum

14.3 H2 2.6 75 18 7 48.7

14.2 H1 4.2 25 22 53 64.1

14.2 H3 2.8 47 20 33 56.4

14.1 H4 2.0 54 19 27 48.2

14.1 H5 2.7 41 20 39 53.6

JL 8.5 H17 5.1 23 24 53 66.4

7.9 H18 3.1 14 21 65 59.2

8

Table 3. Elemental contaminants in whole-sediment samples collected from the Haw River (mg/kg dry weight, or parts per million). Only chromium

at site H8 (in bold) exceeded threshold-effects concentration (TEC) guidelines of MacDonald et al. (2000); sample results less than these values are

not expected to produce adverse effects to sensitive aquatic organisms. No samples exceeded probable effects concentrations (PECs) – values above

which adverse effects to sediment dwelling organisms may be expected. D = data reported from a dilution. B = zinc was detected in the laboratory

blank, but at concentrations less than 0.1 mg/kg.

River Mile Sample ID Al As Cd Cr Cu Fe Pb Mn Hg Ni Zn

Sw

epso

nvil

le

37.4 H15 8950 <0.2 <0.03 20.7 11.1 20100 D 9.92 621 0.03 7.07 35.2 B

37.4 H16 12000 <0.2 <0.03 22.0 16.9 23700 D 10.8 586 0.05 9.20 60.0 B

37.2 H7 11200 <0.2 <0.03 41.5 18.1 21300 D 14.1 645 0.06 8.94 71.6 B

36.9 H6 11100 <0.2 <0.03 26.0 15.6 21600 D 12.2 606 0.04 8.81 64.5 B

36.8 H14 10600 <0.2 <0.03 29.8 19.5 17500 16.8 743 0.07 9.81 106 B

36.7 H13 6990 <0.2 <0.03 21.2 11.2 12200 10.2 756 0.05 6.64 66.2 B

Sax

apah

aw

33.1 H8 12000 <0.2 <0.03 62.6 21.4 19300 17.1 656 0.11 9.60 99.3 B

32.8 H9 10900 <0.2 <0.03 40.8 16.2 19500 D 12.8 531 0.09 8.38 73.7 B

32.2 H10 16500 <0.2 <0.03 40.1 25.0 29400 D 19.3 774 0.09 12.7 120 B

32.1 H11 6340 <0.2 <0.03 20.5 9.41 11900 8.05 313 0.04 5.64 56.5 B

32.0 H12 8600 <0.2 <0.03 24.3 13.1 15300 10.4 423 0.06 8.51 73.4 B

Bynum

14.3 H2 8590 <0.2 <0.03 42.0 12.3 13800 10.7 484 0.09 5.83 66.2

14.2 H1 13800 <0.2 <0.03 29.1 17.5 21300 14.6 1170 0.08 8.89 112

14.2 H3 10200 <0.2 <0.03 23.2 12.5 16100 10.6 788 0.06 6.47 74.5

14.1 H4 6560 <0.2 <0.03 17.9 7.82 10700 6.95 426 0.04 4.24 51.3

14.1 H5 9500 <0.2 <0.03 22.5 12.8 13800 9.95 400 0.05 6.08 62.2

JL 8.5 H17 15200 <0.2 <0.03 33.3 23.2 24300 17.9 966 0.10 11.0 116 B

7.9 H18 14900 <0.2 <0.03 30.3 21.2 20100 15.5 713 0.08 10.2 96.9 B

TEC 9.79 0.99 43.4 31.6 35.8 0.18 22.7 121

PEC 33 4.98 111 149 128 1.06 48.6 459

15

9

Table 4. Polycyclic aromatic hydrocarbons measured in whole-sediment samples collected from the Haw River. All data are µg/kg dry weight (parts

per billion). For each compound, results are compared to threshold-effects concentration (TEC) guidelines of MacDonald et al. (2000) -- values

below which adverse effects to sensitive aquatic organisms are not expected to occur, and probable effects concentrations (PECs) -- values above

which adverse effects to sediment dwelling organisms may be expected. U = not detected.

River

Mile

Sample

ID Ben

zo(a

)anth

race

ne

Ben

zo(a

)pyre

ne

Ben

zo(b

)flu

ora

nth

ene

Ben

zo(g

,h,i

)per

yle

ne

Ben

zo(k

)flu

ora

nth

ene

Chry

sene

Dib

enzo

(a,h

)anth

race

ne

Flu

ora

nth

ene

Inden

o(1

,2,3

-cd)p

yre

ne

Phen

anth

rene

Pyre

ne

Sw

epso

nvil

le 37.4 H15 180 200 260 100 91 170 1 U 520 100 200 440

37.4 H16 190 220 300 110 110 240 1 U 570 110 190 480

37.2 H7 150 200 240 130 110 160 1 U 450 130 180 380

36.9 H6 150 190 230 140 110 190 1 U 410 130 130 350

36.8 H14 160 190 260 110 100 200 1 U 410 110 130 340

36.7 H13 130 160 230 95 77 160 1 U 330 95 100 290

Sax

apah

aw 33.1 H8 220 290 360 200 150 300 76 620 190 200 540

32.8 H9 180 180 220 110 74 130 1 U 310 97 97 310

32.2 H10 140 170 250 120 3 U 170 2 U 330 110 95 280

32.1 H11 170 200 240 120 110 200 1 U 420 120 120 350

32.0 H12 150 190 250 120 83 180 1 U 390 110 120 330

By

nu

m

14.3 H2 98 85 130 2 U 3 U 65 1 U 160 1 U 2 U 140

14.2 H1 170 160 200 110 4 U 120 2 U 330 100 150 270

14.2 H3 110 110 160 84 3 U 84 2 U 220 2 U 92 190

14.1 H4 120 100 150 77 3 U 84 1 U 210 71 71 190

14.1 H5 320 270 310 190 150 230 72 670 170 390 520

JL 8.5 H17 160 190 290 99 4 U 190 2 U 430 99 150 350

7.9 H18 110 130 200 2 U 3 U 120 2 U 250 2 U 2 U 210

TEC 108 150 166 33 423 204 195

PEC 1050 1450 1290 2230 1170 1520

16

9

Table 5. Response of Hyalella azteca in 28-d whole-sediment exposures, Chironomus dilutus in 10-d whole-sediment exposures, and

Ceriodaphnia dubia in 2-d elutriate exposures prepared from sediment samples collected from impounded reaches of the Haw River and to

a control sediment (WB). Means (standard error of the means in parentheses) with an asterisk (H1, 2, 16, and 17) within a column are

significantly different than the control (p <0.05).

River Site Amphipod Amphipod Amphipod

Midge Midge

Midge Cladoceran

Mile ID Survival (%) Length (mm) Biomass (mg)

Survival (%) AFDW (mg)

Biomass (mg) Survival (%)

Sw

epso

nvil

le 37.4 H15 95 (2.89) 4.74 (0.05) 5.18 (0.19)

93 (4.79) 1.09 (0.08)

9.95 (0.22) 100 (0.00)

37.4 H16 95 (2.89) 4.52 (0.24) 4.72 (0.75)

90 (0.00) NM

NM 10 (10.00)*

37.2 H7 95 (5.00) 4.43 (0.17) 4.43 (0.40)

98 (2.50) 0.84 (0.05)

8.21 (0.70) 80 (13.33)

36.9 H6 98 (2.50) 4.68 (0.14) 5.14 (0.46)

70 (17.80) 0.92 (0.07)

6.74 (1.84) 100 (0.00)

36.8 H14 95 (5.00) 4.77 (0.03) 5.25 (0.24)

98 (2.50) 1.20 (0.11)

11.82 (0.67) 100 (0.00)

36.7 H13 95 (5.00) 4.45 (0.09) 4.41 (0.16)

100 (0.00) 0.97 (0.21)

10.12 (2.09) 100 (0.00)

Sax

apah

aw 33.1 H8 93 (4.79) 4.69 (0.03) 4.84 (0.17)

100 (0.00) 1.55 (0.36)

15.44 (3.65) 90 (10.00)

32.8 H9 100 (0.00) 4.00 (0.12) 3.36 (0.28)

98 (2.50) 1.03 (0.22)

10.08 (2.19) 90 (10.00)

32.2 H10 98 (2.50) 4.25 (0.04) 3.98 (0.26)

98 (2.50) 0.64 (0.14)

6.30 (1.45) 90 (10.00)

32.1 H11 98 (2.50) 4.38 (0.12) 4.40 (0.36)

98 (2.50) 1.04 (0.14)

9.97 (1.04) 100 (0.00)

32.0 H12 98 (2.50) 4.36 (0.12) 4.24 (0.26)

100 (0.00) 0.94 (0.14)

9.37 (1.40) 100 (0.00)

Bynum

14.3 H2 80 (10.80)* 4.64 (0.06) 4.11 (0.61)

98 (2.50) 1.17 (0.13)

11.35 (0.90) 70 (15.28)*

14.2 H1 95 (2.89) 4.65 (0.03) 4.87 (0.24)

98 (2.50) 1.18 (0.03)

11.78 (0.50) 70 (15.28)*

14.2 H3 100 (0.00) 5.09 (0.13) 6.80 (0.54)

100 (0.00) 1.12 (0.09)

11.24 (0.94) 100 (0.00)

14.1 H4 95 (2.89) 4.92 (0.16) 5.86 (0.74)

95 (2.89) 1.01 (0.08)

9.56 (0.77) 90 (10.00)

14.1 H5 98 (2.50) 4.73 (0.14) 5.36 (0.60)

93 (2.50) 1.06 (0.19)

9.75 (1.64) 100 (0.00)

JL 8.5 H17 100 (0.00) 5.08 (0.22) 6.79 (0.84)

90 (4.08) 1.41 (0.21)

12.69 (1.92) 30 (15.28)*

7.9 H18 98 (2.50) 4.78 (0.24) 5.81 (0.87)

100 (0.00) 1.12 (0.21)

11.17 (2.07) 100 (0.00)

WB 93 (2.50) 4.52 (0.08) 4.43 (0.29)

96 (1.83) 0.83 (0.04)

8.04 (0.41) 100 (0.00)

* = Significantly different from control for that endpoint

NM = Not Measured (weigh boats melted)

Starting length of amphipods = 2.14 mm

Starting biomass of amphipods = 1.34 mg

17

Table 6. Water quality characteristics in 2-d elutriate exposures with Ceriodaphnia dubia prepared from Haw River sediment samples

and a control sediment (WB).

River

Mile

Temp

(oC)

Dissolved

oxygen

(mg/L)

Conductivity

(uS@25oC)

Alkalinity

CaCO3

Total

ammonia

(mg/L)

Unionized

ammonia

(mg/L)

Hardness

CaCO3

Sample

ID

pH

Sw

epso

nvil

le

37.4 H15 21.2 4.0 216 7.01 140 1.31 0.0058 92

37.4 H16 21.0 4.3 268 7.07 140 2.36 0.0119 80

37.2 H7 18.9 2.1 317 7.07 120 1.61 0.0070 90

36.9 H6 19.3 2.7 305 7.02 128 2.98 0.0118 80

36.8 H14 21.3 3.3 379 7.13 160 5.98 0.0353 116

36.7 H13 21.3 3.6 295 7.17 126 4.34 0.0281 84

Sax

apah

aw

33.1 H8 18.6 2.0 305 6.97 122 2.35 0.0079 90

32.8 H9 19.1 3.4 227 7.25 90 0.61 0.0040 80

32.2 H10 18.6 2.4 287 6.96 120 2.65 0.0087 80

32.1 H11 21.6 3.7 214 7.07 88 1.45 0.0076 82

32 H12 21.0 3.3 231 7.12 90 1.68 0.0095 76

Bynum

14.3 H2 21.6 3.2 244 7.13 110 1.53 0.0092 80

14.2 H1 19.3 2.1 324 7.03 150 5.24 0.0213 90

14.2 H3 18.8 2.5 299 6.98 176 3.54 0.0123 82

14.1 H4 21.6 3.2 308 7.04 140 3.10 0.0152 90

14.1 H5 21.6 3.5 257 6.97 106 2.33 0.0097 90

JL 8.5 H17 19.9 2.7 373 6.94 160 2.48 0.0085 120

7.9 H18 21.0 3.6 254 7.05 100 3.03 0.0146 80

WB 22.0 3.6 225 7.03 88 2.20 0.0109 84

18

Table 7. Elemental contaminant concentrations (µg/L) of 2-d elutriate exposures with Ceriodaphnia dubia prepared from Haw River

sediment samples and a control sediment (WB).

B = aluminum, iron and manganese were detected in the blank, but at concentration much lower than the actual samples; the presence

of these metals in the blank should not affect interpretation of results

J = less than reporting limit (estimated value)

River Mile Sample ID Al As Cd Cr Cu Fe Pb Mn Ni Zn

Sw

epso

nvil

le

37.4 H15 247 B <2.8 <0.36 <1.0 <1.60 1280 B <1.9 8540 B 2.0 J 10.3

37.4 H16 1040 B <2.8 <0.36 <1.0 4.30 J 1640 B 2.4 J 3730 B 3.2 J 33.3

37.2 H7 2200 B <2.8 <0.36 <1.0 16.4 5760 B 21.5 4050 B 3.5 J 70.6

36.9 H6 3120 B <2.8 <0.36 <1.0 6.60 J 8890 B 25.2 3700 B 3.8 J 50.8

36.8 H14 60 BJ <2.8 <0.36 <1.0 <1.60 1050 B <1.9 6790 B 6.0 J 6.1 J

36.7 H13 861 B <2.8 <0.36 9.3 J 5.60 J 4100 B 3.0 J 5890 B 23.5 59.6

Sax

apah

aw

33.1 H8 880 B <2.8 <0.36 <1.0 <1.60 6920 B 19.6 4640 B <1.8 13.5

32.8 H9 2670 B <2.8 <0.36 3.2 J 19.8 3570 B 169 2640 B 6.9 J 73.8

32.2 H10 5220 B <2.8 <0.36 <1.0 <1.60 15600 B 72.8 4140 B <1.8 32.0

32.1 H11 110 B <2.8 <0.36 <1.0 3.20 J 902 B <1.9 2650 B <1.8 15.6

32 H12 540 B <2.8 <0.36 <1.0 2.90 J 1340 B 17.7 2960 B <1.8 45.2

Bynum

14.3 H2 2550 B <2.8 <0.36 1.9 J <1.60 5620 B 4.1 J 3510 B <1.8 16.2

14.2 H1 1200 <2.8 <0.36 <1.0 <1.60 9250 8.1 J 8110 3.1 J 54.0

14.2 H3 1110 B <2.8 <0.36 <1.0 <1.60 6700 B 8.3 J 4910 B <1.8 15.2

14.1 H4 1220 B <2.8 <0.36 <1.0 2.20 J 6530 B 3.0 J 5080 B 2.1 J 25.1

14.1 H5 262 B <2.8 <0.36 <1.0 <1.60 748 B <1.9 2710 B <1.8 38.3

JL 8.5 H17 96 BJ <2.8 <0.36 <1.0 <1.60 1680 B <1.9 8040 B 1.8 J 8.0 J

7.9 H18 1160 B <2.8 <0.36 <1.0 5.70 J 3510 B 3.0 J 5990 B 4.4 J 54.3

WB 216 B 5.6 JB <0.36 <1.0 4.20 J 2450 B 2.0 J 7480 6.2 J 36.1

19

Table 8. Water quality characteristics of pore water isolated from Haw River sediment samples and a control sediment (WB).

River

Mile

Sample

ID

Temp

(oC)

Dissolved

oxygen

(mg/L)

Conductivity

(uS@25oC) pH

Alkalinity

CaCO3

Total

ammonia

(mg/L)

Unionized

ammonia

(mg/L)

Hardness

CaCO3

Sw

epso

nvil

le

37.4 H15 19.2 2.8 807 7.05 850 5.22 0.0220 370

37.4 H16 19.3 2.9 1084 7.09 424 10.0 0.0465 320

37.2 H7 16.1 2.8 742 7.06 292 2.2 0.0075 220

36.9 H6 17.8 2.3 671 6.97 300 5.8 0.0184 170

36.8 H14 19.2 1.8 1070 7.01 534 17.4 0.0669 320

36.7 H13 17.1 2.2 889 7.01 434 12.0 0.0395 260

Sax

apah

aw

33.1 H8 17.7 2.5 641 6.94 316 3.64 0.0107 200

32.8 H9 17.5 2.6 361 7.16 160 0.97 0.0046 130

32.2 H10 16.4 2.0 551 6.94 250 5.06 0.0135 134

32.1 H11 17.7 3.3 473 7.11 220 3.61 0.0156 148

32 H12 18.7 2.6 582 7.05 280 4.24 0.0172 190

Bynum

14.3 H2 17.3 2.2 576 7.06 280 3.55 0.0133 182

14.2 H1 16.1 2.4 983 7.00 500 14.3 0.0427 260

14.2 H3 18.2 3.4 726 7.02 562 6.72 0.0246 402

14.1 H4 16.9 2.6 703 7.03 346 6.56 0.0223 204

14.1 H5 17.7 4.0 590 7.02 276 5.52 0.0195 164

JL 8.5 H17 19.3 2.5 1008 6.99 520 17.7 0.0655 310

7.9 H18 19.3 2.3 808 7.00 400 10.5 0.0398 266

WB 18.6 3.4 635 7.12 254 8.80 0.0417 234

20

Table 9. Elemental contaminant concentrations (µg/L) of pore water isolated from Haw River whole-sediment samples and a control

sediment (WB).

D = sample result based on analyses of dilution

J = less than reporting limit (estimated value)

River Mile Sample ID Al As Cd Cr Cu Fe Pb Mn Ni Zn

Sw

epso

nvil

le

37.4 H15 639 <2.8 <0.36 <1.0 <1.60 56900 6.2 J 39700 D <1.8 27.7

37.4 H16 2260 <2.8 <0.36 <1.0 <1.60 39500 8.4 J 14000 13.4 16.6

37.2 H7 2100 <2.8 <0.36 <1.0 4.60 J 25400 13.2 10300 1.8 J 77.7

36.9 H6 229 <2.8 <0.36 <1.0 <1.60 15000 2.9 J 11300 <1.8 14.6

36.8 H14 1440 <2.8 <0.36 <1.0 <1.60 46700 7.6 J 20700 <1.8 33.8

36.7 H13 387 <2.8 <0.36 <1.0 <1.60 28600 <1.9 16200 <1.8 6.0 J

Sax

apah

aw

33.1 H8 4870 <2.8 <0.36 30.0 9.80 J 45300 22.7 12200 1.9 J 64.0

32.8 H9 17000 <2.8 <0.36 119 53.0 28600 46.6 4900 9.6 J 120

32.2 H10 10100 <2.8 <0.36 6.4 J 15.8 39900 23.0 8950 2.6 J 60.2

32.1 H11 499 <2.8 <0.36 <1.0 <1.60 9370 2.2 J 6280 4.6 J 19.2

32 H12 1360 <2.8 <0.36 <1.0 6.40 J 17000 4.8 J 7590 2.2 J 42.1

Bynum

14.3 H2 742 <2.8 <0.36 <1.0 <1.60 12300 2.1 J 8900 3.2 J 9.3 J

14.2 H1 1160 <2.8 <0.36 <1.0 <1.60 43800 6.3 J 28000 <1.8 49.1

14.2 H3 1000 <2.8 <0.36 <1.0 <1.60 26500 3.6 J 15900 <1.8 13.0

14.1 H4 690 <2.8 <0.36 <1.0 <1.60 22600 3.1 J 14900 <1.8 23.3

14.1 H5 529 <2.8 <0.36 <1.0 <1.60 16200 <1.9 8410 <1.8 8.9 J

JL 8.5 H17 1930 <2.8 <0.36 <1.0 <1.60 58200 6.6 J 21600 3.5 J 59.9

7.9 H18 3280 <2.8 <0.36 <1.0 <1.60 54500 10.9 15000 <1.8 60.7

WB 1810 B 9.3 JB <0.36 <1.0 23.3 28700 B 18.4 20900 19.2 97.9

21

Table 10. Mean water quality characteristics of overlying water in whole-sediment toxicity tests with Hyalella azteca and Haw River

sediments and a control sediment (WB).

River

Mile

Sample

ID

Temp

(oC)

Dissolved

oxygen

(mg/L)

Conductivity

(uS@25oC) pH

Alkalinity

CaCO3

Total

ammonia

(mg/L)

Unionized

ammonia

(mg/L)

Hardness

CaCO3

Sw

epso

nvil

le

37.4 H15 23 5.05 247 7.99 109 0.980 0.0206 129

37.4 H16 23 4.73 243 7.87 110 0.988 0.0235 116

37.2 H7 23 5.24 244 8.01 100 0.336 0.0066 112

36.9 H6 23 5.18 239 7.99 95 0.093 0.0017 113

36.8 H14 23 5.07 245 7.93 94 1.604 0.0295 117

36.7 H13 23 5.58 238 8.04 98 1.056 0.0205 118

Sax

apah

aw

33.1 H8 23 5.17 242 8.00 100 0.621 0.0113 114

32.8 H9 23 6.04 231 8.05 100 0.157 0.0034 112

32.2 H10 23 5.45 236 7.97 97 0.568 0.0090 111

32.1 H11 23 5.13 235 7.93 99 0.330 0.0067 112

32 H12 23 4.95 237 7.96 97 0.401 0.0076 116

Bynum

14.3 H2 23 5.19 238 8.04 96 0.505 0.0034 117

14.2 H1 23 5.22 240 7.89 102 1.622 0.0246 112

14.2 H3 23 5.19 241 7.89 98 0.869 0.0137 118

14.1 H4 23 5.15 239 7.98 99 0.753 0.0145 114

14.1 H5 23 4.91 237 7.88 101 0.851 0.0158 115

JL 8.5 H17 23 5.22 240 7.95 106 0.992 0.0194 115

7.9 H18 23 5.46 234 7.98 102 0.993 0.0195 115

WB 23 6.11 231 8.23 96 1.730 0.0269 104

22

Table 11. Mean water quality characteristics of overlying water in whole-sediment toxicity tests with Chironomus dilutus and Haw

River sediments and a control sediment (WB).

River

Mile

Sample

ID

Temp

(oC)

Dissolved

oxygen

(mg/L)

Conductivity

(uS@25oC) pH

Alkalinity

CaCO3

Total

ammonia

(mg/L)

Unionized

ammonia

(mg/L)

Hardness

CaCO3

Sw

epso

nvil

le

37.4 H15 23 5.28 252 8.03 105 1.066 0.0558 119

37.4 H16 23 5.32 252 8.08 110 1.173 0.0699 111

37.2 H7 23 5.55 239 8.06 95 0.393 0.0203 105

36.9 H6 23 5.68 236 8.08 97 0.180 0.0113 105

36.8 H14 23 5.16 250 8.07 93 1.826 0.0897 108

36.7 H13 23 4.97 244 8.03 101 1.650 0.0826 112

Sax

apah

aw

33.1 H8 23 5.61 235 8.02 95 0.626 0.0288 107

32.8 H9 23 5.97 229 8.14 97 0.142 0.0087 103

32.2 H10 23 5.36 234 7.97 93 3.610 0.1730 103

32.1 H11 23 5.32 233 8.12 97 0.405 0.0233 106

32 H12 23 4.97 239 8.03 96 0.569 0.0284 103

Bynum

14.3 H2 23 5.35 235 7.99 91 0.569 0.0111 103

14.2 H1 23 5.28 243 7.92 100 1.8405 0.0708 101

14.2 H3 23 5.06 242 7.89 100 1.073 0.0413 106

14.1 H4 23 5.28 238 8.02 98 0.806 0.0392 108

14.1 H5 23 4.79 244 7.97 103 1.278 0.0573 107

JL 8.5 H17 23 4.75 256 7.94 106 1.510 0.0662 108

7.9 H18 23 5.18 238 7.99 102 1.366 0.0651 108

WB 23 5.94 234 8.07 91 0.908 0.0690 103

23

16

Two of the 100% elutriate samples that were found to be particularly toxic to C. dubia (H16 and

H17) were re-tested in a dilution series. Sample site H16 is in the portion of Big Alamance Creek

that is flooded by the impoundment created by the dam at Swepsonville. When re-tested in the

dilution series, C. dubia survival was 40% in the 100% elutriate with 80% survival in the first

dilution, a 50% elutriate sample. Site H17 is from a shoal in the headwaters of Jordan Lake.

When re-tested in the dilution series, C. dubia survival was 70% in the 100% elutriate with 100%

survival in the first dilution, a 50% elutriate sample.

Although the elutriates and pore-water samples are not surface waters, we compared elemental

contaminant concentrations in these media to State water quality standards and action levels

(Table 12). This is not a regulatory application of the standards; it is rather a comparison of test

results to the standards as toxicological benchmarks, or estimates of safe water column

concentrations. Chromium in pore water at site H9 in the Saxapahaw Dam impoundment was

measured at 119 μg/L. Copper, lead, and zinc in the elutriate and pore water samples exceeded

State standards infrequently but most commonly in samples from the Saxapahaw Dam

impoundment. This is an indication that aggressive re-suspension of sediments like those tested

could temporarily impair surface water quality.

Table 12. Haw River sediment elutriates and pore water exceedences of North Carolina water

quality standards or action levels for elemental contaminants (NCDENR 2004). Analytical data

for elutriates and pore water are in Tables 7 and 9.

Contaminant

Standard or Action

Level

Elutriate samples in

excess of threshold (%)

Pore water in excess of

threshold (%)

Arsenic 50 μg/L 0 (max <2.8 μg/L) 0 (max <2.8 μg/L)

Cadmium 2 μg/L 0 (max <0.36 μg/L) 0 (max <0.36 μg/L)

Chromium 50 μg/L 0 (max = 9.3 μg/L) 6 (max = 119 μg/L)

Copper 7 μg/L 11 (max = 19.8 μg/L) 17 (max = 53.0 μg/L)

Lead 25 μg/L 17 (max = 169 μg/L) 6 (max = 46.6 μg/L)

Nickel 88 μg/L 0 (max = 23.5 μg/L) 0 (max = 13.4 μg/L)

Zinc 50 μg/L 33 (max = 73.8 μg/L) 33 (max = 120μg/L)

Collectively, the whole-sediment chemistry results indicate minimal contamination which is

consistent with the lack of toxicity in the whole-sediment samples in the amphipod and midge

tests (Table 2).

A potential explanatory variable for the toxicity of elutriates to C. dubia at sites H1, H2, H16 and

H17 (Table 5) is manganese in elutriates (Table 7). Stubblefield and Hockett (2000) report a

geometric mean LC50 (median lethal concentration) from eight manganese toxicity tests with C.

dubia of 15.4 mg/L (data normalized to a hardness of 50 mg/L as CaCO3). Similarly, Lasier et

24

25

al. (2000) report a C. dubia LC50 of 14.5 mg/L for manganese at a hardness of 93 mg/L as

CaCO3. The Haw River sediment elutriates ranged in hardness from 76 to 120 mg/L as CaCO3

(Table 6). To approximate a threshold at which lethal effects may begin, we multiplied the LC50

reported by Lasier et al. (2000) by 0.5. This yields an estimated lethal effects threshold of 7.2

mg/L (or 7,200 μg/L) for manganese. Evaluation of acute toxicity data over a large number of

tests and species has generally shown that dividing an LC50 or EC50 by 2 (i.e., multiplying by

0.5) provides an estimate of a concentration near or below the lethality threshold. The technical

rationale for dividing by 2 is found in the Federal Register notice soliciting comment on

USEPA’s methodology for deriving water quality criteria (43 FR 21506, May 18, 1978)

(Stephan et al. 1985). Because the estimate was derived for a large battery of species and

chemicals, it may not be accurate for particular individual species and chemical combinations,

but it is useful for risk screening purposes.

Elutriate manganese concentrations from two of the four sites exhibiting toxicity (H1, 8.1 mg/L),

and H17 (8.0 mg/L) exceeded the 7.2 mg/L estimated lethal effects threshold concentration for

C. dubia and manganese (Table 7). The other two samples exhibiting toxicity, H2 (3.5 mg/L),

and H16 (3.7 mg/L) did not exceed this threshold. Manganese is a naturally occurring and very

common element in soils and surface waters; among the heavy metals, only iron is more

abundant in the earth’s crust (ATSDR 2000). Impoundments have the potential to increase metal

concentrations due to soil disturbance and increased surface area exposed to water. Elevated

manganese was the number one problem associated with water quality downstream of Tennessee

dams in a recent evaluation (Arnwine et al 2006). Anthropogenic enrichment of manganese can

occur through burning fossil fuels, steel production, battery manufacturing, animal feed

supplements, fertilizers, wastewater treatments plants (using potassium permanganate),

manganese-based fungicides, and antiknock fuel additives (ATSDR 2000).

If it becomes important to more definitively assess the cause of toxicity in the sediment elutriate

samples, there are well established toxicity identification evaluation (TIE) approaches that can be

applied (USEPA 1993 b, c, Besser at al. 1998, Boucher and Watzin 1999). Non-toxic elutriate

samples could be spiked with increasing concentrations of manganese to determine toxic

concentrations of these constituents to C. dubia in a manner inclusive of site-specific elutriate

chemistry. Procedures to reduce concentrations of elutriate components (e.g. sequester metals

like manganese) also exist to investigate how their presence or absence explains toxicity.

Elutriate tests aid in the evaluation of the effects of suspended sediments (e.g., dredged material

evaluations) within the water column. Mobilization of sediments we tested may be a short-term

water column concern based on the elutriate toxicity test results. While sediment re-suspension

and contaminant release in the elutriate tests may be near a worst case simulation of actual

conditions following sediment disturbing activities, additional synthesis is needed to characterize

the nature and magnitude of this issue. In particular, data on the modeled or measured sediment

re-suspension caused by specific sediment disturbing activities will help put the elutriate test

results in context for normal sediment management practices. The joint U.S. EPA and U.S.

Army Corps of Engineers Inland Testing Manual (USEPA/USACE 1998) contains sediment fate

models which may be helpful for this purpose. It would also be useful to evaluate the relative

sensitivity of C. dubia to other freshwater organisms, particularly those resident to the Haw

River.

26

Restoration Systems LLC (2008) examined sediment accumulation in the dams we evaluated.

They concluded that the Swepsonville Dam is not very effective at retaining fine sediments and

that removal of that dam would likely have a de minimis impact on sediment mobilization. From

a pollutant perspective, our surface samples that were targeted to depositional areas are

considered to represent the upper range of expected contaminant concentrations.

Restoration Systems’ LLC (2008) review of the Saxapahaw Dam indicates it has been effective

at trapping sediment with appreciable accumulation into a distinct wedge of fine sediment,

starting ~1000 feet from the dam. Given the site’s character of deposition and the watershed’s

industrial history, they recommended that the sediment wedge be heavily sampled and analyzed

for pollutants in a depth profile because of the likelihood of historic sediment accumulation and

the projection that considerable channel incision (on the order of 10+ feet) is likely to occur if

the dam was completely removed (without dredging stored sediments). From a pollutant

perspective, our surface samples that were targeted to depositional areas are considered to

represent only the recently deposited material at this location.

Restoration Systems’ LLC (2008) review of the Bynum Dam indicated the river at that location

is characterized by fairly coarse bed material, including large rock outcrops which produce a

pattern of patchy, localized sediment retention and island formation. The Bynum impoundment

has not been an effective sediment trap through time and the majority of the trapped sediment is

sand and gravel. It was suggested that removal of that dam would likely have a de minimis

impact on sediment mobilization with the majority of movement coming from erosion of islands

near the dam, at least the edges of which are made of flocculent depositional material. We

targeted these edges in our sampling, so from a pollutant perspective our surface samples that

were targeted to depositional areas are considered to represent the upper range of expected

contaminant concentrations in material that could be transported downstream.

In summary, eighteen whole-sediment samples from within the impounded reaches of

Swepsonville Dam, Saxapahaw Dam, Bynum Dam, and B. Everett Jordan Dam were collected in

June 2008. All samples were analyzed for elemental contaminants and polycyclic aromatic

hydrocarbons. All samples were also assessed with a battery of toxicity tests. Elemental

contaminant concentrations in whole sediments were below those of toxicological significance.

One or more sediment PAHs with freshwater sediment threshold effects (TEC) screening values

(MacDonald et al. 2000) were in excess of TECs at 17 of the 18 sites, but no samples exceeded

the probable effects concentrations (PECs). Survival of Hyallela azteca (freshwater amphipod)

exposed to sediments from site H2 in the Bynum Dam impounded reach was 80% and

statistically lower than controls in 28-d toxicity tests; amphipod growth was not affected at this

or any other site. Whole sediments had no significant effect on survival or growth in 10-d tests

with Chironomus dilutus (freshwater midge) at any of the 18 sites. Results indicate the

contaminants associated with the whole-sediment samples were not chronically toxic to

amphipods or midge. In 2-d sediment elutriate (water-extractable fraction) tests with

Ceriodaphnia dubia (freshwater cladoceran), statistically-significant reductions in survival

occurred in four of the 18 exposures (H1 and H2 within the Bynum Dam impounded reach, site

H16 in the flooded portion of Big Alamance Creek, and site H17 in the headwaters of Jordan

Lake). Chromium in pore water at site H9 in the Saxapahaw impoundment was measured at 119

μg/L; the State standard is 50 μg/L. Copper, lead, and zinc in the elutriate and pore water

samples exceeded State standards infrequently but most commonly in sediments collected from

the Saxapahaw Dam impoundment. This is an indication that aggressive re-suspension of

sediments like those tested could temporarily impair surface water quality.

These data and surveys of sediment physical characteristics (Restoration Systems, LLC. 2008),

volume, and likelihood of movement can be used together to infer the impacts the different types

of sediments disturbing activities on short-term water column chemistry. While sediment re-

suspension and contaminant release in the elutriate tests may be near a worst case simulation of

actual conditions following sediment disturbing activities, additional synthesis is needed to

characterize the nature and magnitude of this issue. In particular, data regarding the modeled or

measured sediment re-suspension caused by specific sediment disturbing activities (e.g.,

dredging, dam alterations, dam removal, etc.) will help put the elutriate test results in context for

a range of sediment management practices.

Management Recommendations

The study was intended to provide data that facilitates evaluation of dam removal actions. We

will provide these data to dam owners, the North Carolina Dam Removal Task Force, and other

interested stakeholders with recommendations on sediment quality which will help them further

prioritize and plan management of these structures.

A concurrent assessment of sediment physical characteristics and volume was conducted by

Restoration Systems, LLC (2008). Our data and theirs could be further integrated to evaluate

sediment transport scenarios to better inform sediment management at these dams.

Additional data exploration with USGS could be conducted to investigate the source(s) of the

reduced test organism survival in four of the sediments. Pairwise correlations among the C.

dubia survival results and sediment and elutriate chemical analyses may be helpful, but there is

not much resolution in the toxicity test results to support this assessment. Concentrations of

individual metals in sediment, total PAHs, and individual PAHs were not a concern. Additional

analyses of sediment quality may include calculating mean quotients based on probable effects

concentrations(PEC-Q) to provide an overall measure of chemical contamination and to support

an evaluation of the combined effects of multiple contaminants (MacDonald et al. 2000; USEPA

2000b). Relationships between toxicity and concentrations of PAHs in sediment samples could

be further examined using equilibrium partitioning sediment guideline toxic units (ESGTU;

USEPA 2003). The ESGTUs are a way of summarizing many PAHs compounds into one

representative number. An ESGTU is basically the organic carbon normalized concentration of a

chemical divided by a toxicity threshold (this is a toxic unit for the specific chemical). Then the

ESGTU for specific chemicals are summed for each sample yielding ΣESGTUs. These

additional analyses will obviously not change the conclusion that sediments were either non-

toxic or of low toxicity in solid phase exposures, but they may help explain the patterns and

significance of the low level PAH contamination we measured.

27

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