Abstract

A small, PCB-contaminated hazardous waste site at the 

downstream end of the Sherman Island Pool of the upper 

Hudson River (New York) was partially remediated in 1996. 

Remediation included removal of contaminated on-site soil 

and adjacent sediment along the river shoreline that was 

exposed while the water level in the pool was lowered by four 

feet during the remediation. 

Annual fish monitoring over a ten year period from several 

locations within the pool, including stations downstream 

and directly across the pool from the site, demonstrated 

that PCB contamination in fish in the immediate vicinity 

of the site was reduced following remediation. However, 

PCB contamination remains in the river sediment adjacent 

to the site and elevated PCB concentrations continue to be 

observed in fish collected at the station adjacent to the site, 

particularly in small fish. We used a multiplicative equation 

to model PCB concentrations in several species of fish as 

a function of collection location and time period, lipid 

content, and length. Multiple linear regression techniques 

were used to examine differences in geometric mean PCB 

concentrations among locations and species and to further 

describe and test for differences in temporal trends among 

locations and species. 

PCB concentrations in several fish species declined 

following remediation, particularly in the station adjacent 

to the site, and differed among locations for each species 

within the relatively small spatial scale of the pool. Mean 

concentrations in fish from the station directly adjacent to the site, except for large yellow perch, were much higher than 

other locations within the pool during the same time-step. The results of our analysis suggest that long-term monitoring 

strategies that do not adequately consider spatial and temporal differences in concentration may mask the importance of 

localized contamination and reduce the ability to discern temporal changes in fish concentrations following remediation or 

natural recovery.

Introduction

The Sherman Island Pool, the reservoir created by the Sherman Island Dam on the Upper Hudson River, is approximately 

210 miles upstream of the Battery in New York Harbor and 3.6 miles (5800 m) long by 700 to 800 feet (230 m) wide. The 

“Queensbury” site, a 0.75 acre area near the downstream end of the Sherman Island Pool with approximately 150 meters 

of shoreline, was designated by New York State Department of Environmental Conservation (NYSDEC) as a hazardous 

waste site in 1989 (Parsons 1994). The contaminated area resulted from the disposal of PCB-laden dielectric fluid from 

capacitors and cooling oil from transformers on the ground. Subsequent runoff and discharge from the disposal practices 

led to significant contamination of the soils on-site and adjacent sediments of the river. Interim remedial measures for 

on-site soils were conducted at the site prior to 1992; however, sediment and fish samples collected in the vicinity of the 

site in 1992 and 1993 showed highly elevated PCB concentrations. 

PCB Concentrations in Fish Following Partial 

Remediation of a Small Hazardous Waste Site

L.J Field1, J.W. Kern2, and R.J. Sloan3

1NOAA’s Office of Response and Restoration, Assessment and Restoration Division, Seattle, Wash.

2Kern Statistical Services, Inc., Sauk Rapids, Minn. 

3New York State Department of Environmental Conservation (retired), Albany, N.Y
Remedial action took place in the summer of 1996. Cleanup levels for soil of one ppm in the top foot and ten ppm in 

subsurface soil resulted in the removal of 3,500 cubic yards. Nearshore sediments were excavated in the dry to a depth 

of two feet and backfilled with clean fill while the reservoir was lowered about four feet for a period of two weeks. The 

excavation included an area of PCB-contaminated sediment near the mouth of a culvert that exceeded 50 ppm. Remaining 

contaminated sediment areas, including approximately 0.05 acres exceeding 50 ppm and 4.4 acres exceeding one ppm, 

were designated as a second Operable Unit (Foster Wheeler 2003).

Objective

Our objective is to evaluate temporal and spatial changes in PCB concentrations in several species of large and small fish 

from multiple sampling locations following partial site remediation. 

Overview of approach

Polychlorinated biphenyls (PCBs) and other lipophilic organic contaminant concentrations in fish tissues are typically 

“normalized” by dividing PCB concentration (Cf) by percent lipid (Fat). This approach relies on two assumptions: 

• PCB concentrations in fish tissue from a given area are expected to be proportional to lipid content; and

• Lipid-normalized PCB concentrations are expected to have lower variability.

Hebert and Keenleyside (1994) found that neither of these assumptions held for their sample data and proposed an 

alternative procedure based on linear regression. In this paper we apply a modification of this approach that does not 

require either a linear relationship between PCB concentration and lipid or a normal distribution.

Fillet TimeStep

Total PCB

(mg/kg, wet wt.)

Total PCB

(mg/kg, Lipid)

Number of

Samples

Total PCB

(mg/kg, wet wt.)

Total PCB

(mg/kg, Lipid)

Number of

Samples

Smallmouth Bass 1 0.86 (0.32-1.21) 93 (37-159) 5 0.20 (0.01-0.91) 22 (0.72-152) 28

Smallmouth Bass 2 0.40 (0.05-1.57) 43 (3.13-224) 23 0.08 (0.02-0.77) 7.20 (2.90-26) 60

Smallmouth Bass 3 0.22 (0.02-0.64) 43.75) 25 0.05 (0.01-0.20) 5.96 (1.25-30) 47

Rock Bass 1 1.49 (0.05-5.60) 167 (3.57-560) 8 0.07 (0.01-0.26) 8.27 (1.89-21) 35

Rock Bass 2 0.33 (0.05-2.52) 46 (4.27-381) 21 0.05 (0.02-0.12) 5.87 (0.52-14) 72

Rock Bass 3 0.20 (0.02-0.70) 17.4 (0.81-74) 25 0.05 (0.01-0.20) 5.11 (0.49-18) 52

Yellow Perch 1 0.18 (0.02-0.84) 34 (2.00-205) 15 0.18 (0.05-0.84) 32 (3.13-220) 31

Yellow Perch 2 0.18 (0.02-0.97) 20 (3.47-156) 27 0.05 (0.02-0.15) 5.70 (1.15-22) 83

Yellow Perch 3 0.09 (0.02-0.34) 12.5 (2.27-71) 33 0.02 (0.01-0.13) 3.24 (0.67-24) 54

Whole Body

Smallmouth Bass 1 6.87 (2.04-11.3) 471 (102-870) 4 0.13 (0.09-0.16) 8.31 (4.45-10.9) 4

Smallmouth Bass 3 0.35 (0.05-0.96) 16.4 (2.36-55) 21 0.09 (0.03-0.32) 4.88 (1.88-19.7) 33

Rock Bass 1

Rock Bass 3 0.40 (0.04-0.94) 14.3 (1.19-33) 38 0.09 (0.02-0.30) 3.65 (0.46-11.8) 59

Yellow Perch 1 10.5 (2.39-19.3) 253 (80-470) 4 0.14 (0.10-0.20) 3.47 (3.10-3.74) 4

Yellow Perch 2 9.76 (0.15-33.7) 495 (7.13-1696) 5 0.09 (0.07-0.12) 3.64 (2.85-4.11) 3

Yellow Perch 3 0.35 (0.03-1.02) 18.3 (1.16-54) 16 0.07 (0.01-0.11) 3.87 (0.91-11.9) 28

Sunfish 1 23.76 766 1

Sunfish 2 5.26 289 1 0.08 (0.07-0.10) 3.58 (3.00-4.45) 3

Sunfish 3 0.27 (0.26-0.28) 9.5 (9.1-9.9) 2

Forage Fish 1 6.24 (4.72-7.48) 371 (196-502) 3 0.10 (0.09-0.12) 2.95 (2.89-3.06) 3

Forage Fish 3 0.58 11 1

Species Queensbury Sherman Island Pool
Figure 1

Station 

River Mile 

Location 

209.5 S herman Island pool 850 m downstream 

of site , upstream of Sherman Island dam 

210.0 Queensbury site 

210.1 Directly across S herman Island pool , 

about 300 m from the site 

211.2 S herman Island pool , below boat launch, 

2100 m upstream of site 

212.0 S herman Island pool , above boat launch, 

3500 m upstream of site 

 
Methods

Most fish were collected under contract to Niagara Mohawk Power Company (NMPC) by Parsons Engineering Company 

personnel with assistance from NYSDEC. Methods for fish collection and sample processing followed standard protocols 

for sample handling and maintaining chain-of-custody as outlined by NYSDEC (Sloan et al. 2002, 2005) and Parsons 

(2006). Principal target species included smallmouth bass (Micropterus dolomieui), rock bass (Ambloplites rupestris), 

and yellow perch (Perca flavescens). Other species used in the analysis to supplement the available small fish, whole body 

sample data include two species groups: sunfish, which include pumpkinseed (Lepomis gibbosus) and bluegill (Lepomis 

macrochirus); forage fish, which include several minnow and darter species (Cyprinid spp., Notropis atherinoides, 

Notropis hudsonius, Luxilus cornutus), fallfish (Semotilus corporalis), and logperch (Percina caprodes)]. Fish were 

captured primarily with variable mesh gill nets and electro-shocking. 

Fish samples were collected in the summer from five stations in the Sherman Island Pool between 1992 and 2005 (Figure 

1; Table 1). Large fish (individual fillet samples) were collected annually at three stations (RM209.5, RM210.0, RM210.1) 

from 1995-2005 and two additional upstream stations (RM211 and RM212) from 1995-2000. Small fish (whole body, 

mostly individual samples but some composites of similarly-sized fish to ensure sufficient tissue mass for analysis) were 

collected in 1993 and annually from the three principal stations from 2001-2005. The target sample size was five samples 

per location for each species. Target sample size was not always achieved; also, additional samples were analyzed by 

NYDEC in some cases. To take into account the changes in sample collection strategy and to increase sample size for 

the statistical comparisons, data were grouped into three time-steps: “Baseline” (pre-removal) 1992-1996 (note that 

sediment remediation in 1996 took place in late August, after fish collections were completed for the year); “Post_1” 

1997-2000; and, “Post_2” 2001-2005. 

Chemical analysis

Most of the fish in the database were collected by NMPC contractors and analyzed for PCBs using standard Aroclor 

analytical methods (SW-846 Method 8082) and percent lipids ((Parsons 2006). Total PCBs represented the sum of 

detected Aroclors or congeners. Detection limits were mostly less than or equal to 50 ng/kg. 

Mathematical Framework

PCB concentrations are typically normalized by dividing by percent lipid content, but this approach includes some 

underlying assumptions that are typically not tested. 

• Lipid-normalized concentrations can be thought of as a regression between concentration and fat. 

• In this paper, we use a more flexible multiplicative model that does not require assumption of a linear regression 

through the origin:

• The null hypothesis: tests the linearity assumption of the usual lipid-normalization method.

• Other factors such as fish length can be included and tested. Lipid- and length-adjusted spatial and temporal 

comparisons of PCB concentrations in fish tissue are made by adding additional terms to the model:

• This is often termed an “analysis of covariance,” because effects are adjusted for “covariation” with continuous 

variables such as lipid and length. Spatial and temporal comparisons were adjusted using the Tukey–Kramer multiple 

comparison procedure (Kramer, 1956).

Results and Discussion 

Data

Limitations in the available data made it necessary to group samples into three time periods: Baseline represented 

samples collected between 1992 and 1996. The Post_1 time-step represented four years, from 1997-2000. During this 

period, large fish were sampled annually at five stations within the Sherman Island Pool and small fish were only collected 

incidentally. The Post_2 time-step represented samples collected between 2001 and 2005. During this period, both large 

and small fish were sampled at three stations. Table 2 shows the arithmetic mean and range of total PCB concentrations 

(wet weight and lipid-normalized) number of samples collected and used in this analysis by species, location, and timestep. 
Model Results

Lipid: Log-transformed PCB concentrations were positively but nonlinearly associated with percent lipid in smallmouth 

bass, rock bass, and yellow perch for both large and small fish, although the slopes of the relationships varied. These 

relationships were significant (p<0.05) for all except small yellow perch (p=0.16). Because the upper confidence limits for 

the log-lipid regression coefficients are less than 1.0, the assumption of linearity between PCB and percent lipid does not 

hold for these species in the Sherman Island Pool. 

Length: Log-transformed PCB concentrations were not significantly associated with log length in either large or small fish. 

Consequently, length was not included in the models used to evaluate temporal and spatial differences.

Predicted versus Observed

Model predictions of total PCB concentrations correlated well with observed results in both large and small smallmouth 

bass, rock bass, and yellow perch (Figure 2). 

Smallmouth Bass (Whole Body)

R2 = 0.78

0.01

0.1

1

10

100

0.01 0.1 1 10 100

Observed

Predicted

Rock Bass (Whole Body)

R2 = 0.58

0.01

0.1

1

10

0.01 0.1 1 10

Observed

Predicted

Yellow Perch (Whole Body)

R2 = 0.69

0.01

0.1

1

10

100

0.01 0.1 1 10 100

Observed

Predicted

Smallmouth Bass (Fillet)

R2 = 0.57

0.01

0.1

1

0.01 0.1 1 10

Observed

Predicted

Rock Bass (Fillet)

R2 = 0.56

0.01

0.1

1

0.01 0.1 1 10

Observed

Predicted

Yellow Perch (Fillet)

R2 = 0.47

0.01

0.1

1

0.01 0.1 1 10

Observed

Predicted

Figure 2
Temporal comparisons within species by station 

Large fish: Estimated mean PCB concentrations in large smallmouth bass decreased from baseline with each time-step 

at the site (RM210.0) and the two stations closest to the site (RM209.5 and RM210.1) (Figure 3). The differences were 

statistically significant (p<0.05) at the second time-step. No differences were observed at the other two stations (RM211.2 

and RM212.0). 

Estimated mean PCB concentrations in rock bass decreased significantly (p<0.05) from baseline with each time-step at 

the site and at the second time-step at the station directly across the reservoir from the site (RM210.1) (Figure 3). No 

temporal differences were observed for the other three stations. 

Yellow perch showed a different pattern than the other two species. Baseline concentrations at the site were lower than 

for the other two species. Estimated mean concentrations decreased significantly from baseline with each time-step at the 

station downstream of the site (RM209.5). None of the other stations showed any significant temporal differences. 

Small fish: Temporal comparisons were limited by the available data for the small fish (whole body). Smallmouth bass and 

yellow perch showed significant decrease in concentration at the site between baseline and the Post_2 time period (Figure 

4). No baseline samples were available for small rock bass. 

Because of the limited data available for small fish, available data for whole body samples of smallmouth bass, rock bass, 

yellow perch, sunfish (pumpkinseed and bluegill), and forage fish (several species) were combined using a “species smash” 

approach (Sloan et al. 2005). The results of this analysis showed that estimated concentrations at the site declined during 

each of the time-steps, but remained higher than the other stations at each time-step (Figure 5). The model showed no 

differences between species groups when lipid, time-step, and location were included in the model. 

Spatial comparisons within species comparisons by station and time-step

Large fish: Baseline (1995-96) estimated, geometric mean PCB concentrations in large fish (fillet samples) adjusted for one 

percent lipid adjacent to the site (RM210.0) were significantly higher than the other four Sherman Island Pool locations 

for smallmouth bass and rock bass, but not for yellow perch (Figure 3). For the Post_1 time period (1997-2000), estimated 

concentrations continued to be significantly higher at the site than the other four stations for smallmouth bass and rock 

bass. PCB concentrations in yellow perch at the site were slightly higher than other stations. For the Post_2 time period 

(2001-2005), only two stations other than the site were sampled. In all three species, concentrations at the site remained 

higher than at the other two stations. 

Small fish: Small fish (whole body samples) were collected for baseline for smallmouth bass and yellow perch, but not for 

rock bass. Except for a few incidental samples during the Post_1 period, small fish were collected from three stations in 

Post_2. Baseline concentrations at the site were significantly (p<0.0001) higher than baseline concentrations at RM212 

in smallmouth bass and yellow perch (Figure 4). No baseline data were available from other stations. Estimated PCB 

concentrations at the site were significantly (p<0.0001) higher for the Post_2 time-step than concentrations at RM209.5 

and RM210.1 in smallmouth bass and rock bass. Post_2 concentrations for yellow perch at the site were similar to Post_2 

concentrations at RM209.5 (p=0.16), but were significantly higher than Post_2 concentrations at RM210.1 (p<0.01). 

Reach Averaging

Common practice in monitoring fish PCB concentrations in riverine or estuarine environments is to treat a geographic 

section (e.g., a river reach) – sometimes defined by dams at the upstream and downstream ends – as a single analysis unit. 

Fish may be collected from single or multiple discrete locations or without regard for location within the reach. Our results 

suggest that in cases where localized areas of contamination exist within the reach, the potential for bioaccumulation may 

be underestimated. 

To illustrate this issue, estimated PCB concentrations for each species (fillet samples) were compared for the station 

adjacent to the site (RM210.0) with concentrations from the combined results from the other Sherman Island Pool 

stations (Figure 7). The results indicate that an average concentration from stations other than adjacent to the site would 

not capture the elevated concentrations at the site in smallmouth bass and rock bass or the temporal changes following the 

remediation. 

Statistical Modeling Approach

The multiplicative model used to analyze these data provided a framework to test important hypotheses in the presence 

of potentially confounding factors. When the dependent variable and the continuous independent variables are log 

transformed, the assumption that PCB concentration is linearly related to independent covariates such as lipid can be 

tested. The usual linear regression through the origin is a special case of the more general multiplicative model. Using 

this model framework, we found that lipid content was the primary driver of variation in PCB content and that variation 

in lipid content tended to mask effects when viewed in terms of unadjusted wet weight concentrations. Subsequent 

comparisons of PCB content among years and locations were conducted after adjusting for covariation with lipid. 
Implications for monitoring

In the database used in our analysis, the numbers of fish in each species group were not always consistent by year and 

location. Missing data made it necessary to group across years to obtain adequate numbers of fish to estimate averages 

at each combination of locations and time-steps. Limited baseline data, particularly for small fish, made it impossible to 

consider annual variability during the baseline period. Our findings suggest that monitoring programs for fish designed 

to evaluate contaminated sediment sites and the effectiveness of remediation should include multi-year, multi-species 

baseline and post-remedial sample collection from discrete locations that take into account known areas of sediment 

contamination. 

Conclusions

The on-site soil and partial sediment remediation conducted in 1996 at the Queensbury site resulted in a rapid decline in 

fish concentrations adjacent to the site and to a lesser degree elsewhere in the Sherman Island Pool. 

PCB concentrations of large smallmouth bass and rock bass and all species of small fish collected from the station adjacent 

to the Queensbury site were consistently higher than other locations. Small fish PCB concentrations remain elevated 

adjacent to the site. 

The multiplicative model provided a useful framework for statistical comparison of fish total PCB concentrations at 

different locations and time-steps, accounting for lipid and length. 

The sampling strategy, which consisted of annual collections of multiple species from discrete locations within Sherman 

Island Pool, was successful in demonstrating the local impact of contaminated sediment on large and small fish and the 

reduction in fish concentrations following remediation. Using a reach-averaging approach to assess PCB contamination in 

fish would likely mask the impact from the contaminated site and recovery following remediation.

Figure 3 Figure 4

Figure 5 Figure 6

0.01 

0.1 

1 

10 

100 

Baseline Post_1 Post_2 Baseline Post_1 Post_2 Baseline Post_1 Post_2 

Bbass Rbass YPerch 

RM209.5 RM210.0 RM210.1 RM212.0 

Total PCBs (mg/kg) 

0.01 

0.1 

1 

10 

Baseline Post_1 Post_2 

RM209.5 RM210.0 RM210.1 RM212.0 

Total PCBs (mg/kg) 

0 

0.2 

0.4 

0.6 

0.8 

1 

1.2 

1.4 

1.6 

QB SI QB SI QB SI 

Bbass Rbass YPerch 

Baseline Post_1 Post_2 

Total PCBs (mg/kg) 

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Baseline Post_1 Post_2 Baseline Post_1 Post_2 Baseline Post_1 Post_2

Bbass Rbass YPerch

RM209.5 RM210.0 RM210.1 RM211.2 RM212.0

Total PCBs (mg/kg)
Acknowledgments

Data for this analysis were extracted from the NYSDEC biota contaminant database. M. Kane (NYSDEC) and C. Severn 

(Premier Environmental Services) provided data management services.

References

Hebert CE, Keenleyside KA. 1994. To normalize or not to normalize? Fat is the question. Environmental Toxicology and Chemistry 

14:801-807.

Foster Wheeler Environmental Corporation. 2003. Queensbury OU-2 Site Draft Supplemental Feasibility Study Report. Prepared 

for Niagara Mohawk, A National Grid Company. Foster Wheeler, Langhorne, Pennsylvania. June 2003.

Kramer CY. 1953. Extension of multiple range tests to group means with unequal numbers of replications. Biometrics 12:307-310. 

Parsons Engineering. 1994. Final Remedial Investigation Report for the Queensbury Site, Town of Queensbury, Warren County, 

New York. Prepared for Niagara Mohawk Power Corporation. Parsons Engineering Services, Syracuse, New York.

Parsons ES. 2006. Annual Fish Tissue Sampling Program Data Report and Eleven-Year Summary (1995-2005). National Grid. 

Queensbury Site, Town of Queensbury, Warren County, New York. January 2006. 

Sloan RJ, Kane MW, and Skinner LC. 2002. 1999 as a Special Spatial Year for PCBs in Hudson River Fish. Bureau of Habitat, 

Division of Fish, Wildlife and marine Resources, New York State Dept. of Environmental Conservation, Albany, New York. 111 p. 

Sloan RJ, Kane MW, and Skinner LC. 2005. Of Time, PCBs and the Fish of the Hudson River. Bureau of Habitat, Division of Fish, 

Wildlife and marine Resources, New York State Dept. of Environmental Conservation, Albany, New York.

Stearns and Wheler. 1997. Remedial Construction Report Queensbury Site Remediation NYSDEC Site #557012, Operable Unit No. 1 

Queensbury, NY February 1997 Stearns & Wheler, LLC.

Figures

Figure 1. Map of Hudson River (inset)

Figure 1. Map of Sherman Island Pool, showing sampling locations

Figure 2a.Observed versus predicted estimated PCB concentration (mg/kg) at 1% lipid in large fish (fillet) samples for smallmouth 

bass, rock bass, and yellow perch. 

Figure 2b.Observed versus predicted estimated PCB concentration (mg/kg) at 1% lipid in small fish (whole body) samples for 

smallmouth bass, rock bass, and yellow perch. 

Figure 3. Estimated geometric mean PCB concentration (mg/kg) and 95% confidence interval adjusted for 1% lipid in large fish 

(fillet samples) by species, location, and time-step. 

Figure 4. Estimated geometric mean PCB concentration (mg/kg) and 95% confidence interval adjusted for 1% lipid in small fish 

(whole body samples) by species group, location, and time-step. 

Figure 5. Estimated geometric mean PCB concentration (mg/kg) and 95% confidence interval adjusted for 1% lipid in small fish 

(whole body samples), all species combined, by location and time-step.

Figure 6. Estimated geometric mean total PCB concentration (mg/kg, wet wt.) and 95% confidence interval at 1% lipid in large fish 

(fillet samples) by species and time-step for Queensbury (QB) and other stations in the Sherman Island Pool (SI). 

Tables

Table 1. Fish sampling locations within the Sherman Island Pool.

Table 2. Arithmetic mean (min, max) total PCBs (mg/kg wet wt), lipid-normalized PCBs (mg/kg lipid), percent lipid, length, and 

number of samples by tissue type, species, and time-step for the Queensbury site (QB) and all other stations in the Sherman Island 

Pool (SI).