U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2012–5191

Prepared in cooperation with the 

Massachusetts Department of Fish and Game, Division of Ecological Restoration

Estimated Sediment Thickness, Quality, and 

Toxicity to Benthic Organisms in Selected 

Impoundments in Massachusetts
Cover. Upper Left—The Ballardville impoundment on the Shawsheen River, Andover, Massachusetts. 

Lower Right—Rice City impoundment on the Blackstone River, Uxbridge, Massachusetts. Photographs by Robert F. Breault.
Estimated Sediment Thickness, Quality, 

and Toxicity to Benthic Organisms in 

Selected Impoundments in Massachusetts

By Robert F. Breault, Jason R. Sorenson, and Peter K. Weiskel

Prepared in cooperation with the 

Massachusetts Department of Fish and Game, Division of Ecological Restoration

Scientific Investigations Report 2012–5191

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2013

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Suggested citation:

Breault, R.F., Sorenson, J.R., and Weiskel, P.K., 2013, Estimated sediment thickness, quality, and toxicity to benthic 

organisms in selected impoundments in Massachusetts: U.S. Geological Survey Scientific Investigations Report 

2012–5191, 42 p., at http://pubs.usgs.gov/sir/2012/5191/.
iii

Acknowledgments

The authors wish to express their gratitude to the Massachusetts Department of Fish and 

Game, Division of Ecological Restoration (DFG/DER) for their support of this study. We would 

particularly like to thank Tim Purinton, Eileen Goldberg, Beth Lambert, Alex Hackman, and Chris 

Leuchtenburg for their assistance throughout. The cooperation of public and private landowners 

who granted permission to access the impoundments also is appreciated.

The authors thank Leslie DeSimone and Jonathan Morrison of the U.S. Geological Survey 

(USGS), and Alex Hackman of the DFG/DER for their technical reviews of the report and Andrew 

Massey and Dave Armstrong of the USGS for their field and modeling assistance. The authors 

also thank Lance Ostiguy and Pete Steeves of the USGS for their geographic information systems assistance, Anna Glover of the USGS for editorial review, and Susan Bergin, Ann Marie 

Squillacci, and others in the USGS Pembroke Publishing Service Center for their work on the 

figures, tables, and layout of the report.
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v

Contents

Acknowledgments........................................................................................................................................iii

Abstract...........................................................................................................................................................1

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

Purpose and Scope ..............................................................................................................................3

Field, Laboratory, and Statistical Methods................................................................................................3

Site Selection and Sampling Techniques .........................................................................................3

Chemical Analysis of Sediment..........................................................................................................4

Analysis of Inorganic Elements.................................................................................................6

Organic Analysis..........................................................................................................................6

Bias and Variability in Field and Laboratory Analyses ..........................................................9

Estimated Toxicity of Sediment...........................................................................................................9

Sediment Thickness, Chemical Quality, and Estimated Toxicity..........................................................10

Measured Sediment Thicknesses and Estimated Volumes.........................................................10

Concentrations of Inorganic Elements............................................................................................10

Concentrations of Organic Compounds..........................................................................................19

Estimated Toxicity of Sediments.......................................................................................................19

Relations Among Contaminant Concentrations, Land Use, and Industrial History ..........................25

Summary........................................................................................................................................................28

References Cited..........................................................................................................................................28

Figures

1. Map showing the locations of dams in Massachusetts ........................................................2

2. Map showing locations of impoundments in Massachusetts assessed in this study 

and the drainage areas to the dams that form the impoundments ......................................4

3. Photographs showing measurement of soft-sediment thickness where A, dam has 

been breached and the impoundment has been drained and B, impoundment is 

present at the time of sampling..................................................................................................6

4. Photographs showing methods used to obtain cores from impoundments.......................7

5. Photographs showing examples of core penetration through the full thickness of 

impounded sediment into preimpoundment material.............................................................8

6. Graphs showing concentrations of A, arsenic, B, cadmium, C, chromium, D, copper, 

E, lead, F, nickel, and G, zinc in sediment samples from 32 impoundments in 

Massachusetts............................................................................................................................12

7. Graphs showing concentrations for A, total polycyclic aromatic hydrocarbons, 

B, total polychlorinated biphenyls, and C, total dichlorodiphenyl-trichloroethylene 

(DDT) compounds in sediment samples from 32 impoundments in Massachusetts.......20
vi

Tables

1. Characteristics of selected dams in Massachusetts and sampling information for 

2004 and 2005.................................................................................................................................5

2. Bottom-sediment thicknesses and estimated volumes of sampled impoundments in 

Massachusetts in 2004 and 2005..............................................................................................11

3. Concentrations of inorganic elements measured in bottom-sediment cores 

collected from selected impoundments in Massachusetts in 2004 and 2005 ..................16

4. Concentrations of organic compounds measured in bottom-sediment cores 

collected from selected impoundments in Massachusetts in 2004 and 2005 ..................31

5. Average probable effects concentration quotients for bottom-sediment cores 

collected from selected impoundments in Massachusetts in 2004 and 2005 ..................23

6. Likelihood of toxicity of bottom-sediment cores collected from selected 

impoundments in Massachusetts in 2004 and 2005..............................................................24

7. Land use characteristics of selected impoundment drainage areas in 

Massachusetts............................................................................................................................26

8. Relations between sediment-core contaminant concentrations and land use in the 

drainage areas of selected impoundments in Massachusetts...........................................27

Conversion Factors, Datum, and Abbreviations

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square foot (ft2

) 0.09290 square meter (m2)

square mile (mi2

) 2.590 square kilometer (km2)

Volume

gallon (gal) 3.785 liter (L)

cubic foot (ft3

) 0.02832 cubic meter (m3)

cubic yard (yd3

) 0.7646 cubic meter (m3)

Mass

ounce, avoirdupois (oz) 28.35 gram (g)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

 °F=(1.8×°C)+32

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Concentrations of chemical constituents (inorganic elements and organic compounds) in 

bottom sediment are given in parts per million (ppm) and parts per billion (ppb).
vii

Abbreviations

AVS acid-volatile sulfides

CIT commercial, industrial, and transportation

DDE dichlorodiphenyl-dichloroethylene

DDT dichlorodiphenyl-trichloroethane

DO dissolved oxygen

ODS Office of Dam Safety

HRGC/LRMS high-resolution gas chromatography/low-resolution mass spectrometry

ICP–MS inductively coupled mass spectrometry

MDFG Massachusetts Department of Fish and Game

MDER Massachusetts Division of Ecological Restoration

NID U.S. Army Corps of Engineers National Inventory of Dams

NIST National Institute of Standards and Technology

NWQL National Water Quality Laboratory

PAH polycyclic aromatic hydrocarbon

PCB polychlorinated biphenyl

PEC probable effects concentration

PECQ probable effects quotient for an individual contaminant in a sample

PECQx average probable effects quotient for a sample

QA/QC quality assurance/quality control

RPD relative percent difference

SOD sediment-oxygen demand

TEC threshold effects concentration

USGS U.S. Geological Survey
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Estimated Sediment Thickness, Quality, and Toxicity 

to Benthic Organisms in Selected Impoundments in 

Massachusetts

By Robert F. Breault, Jason R. Sorenson, and Peter K. Weiskel

Abstract

There are presently more than 3,000 dams in Massachusetts. Many of these dams are no longer used for their original 

purpose, and some are in disrepair. Contaminants bound to 

sediment trapped behind dams have the potential to affect the 

downstream environment in the event of a sudden release or 

dam failure. These sediments may also be an ongoing source 

of contaminants to overlying water and to organisms living 

on or in bottom sediment. In addition, dams do not entirely 

retain impounded sediment and associated contaminants. Such 

sediments are subject to scour, resuspension, and downstream 

redistribution during storm events.

The U.S. Geological Survey and the Massachusetts 

Department of Fish and Game, Division of Ecological 

Restoration, collaborated to collect baseline information 

on the quantity and quality of sediment impounded behind 

selected dams in Massachusetts, including sediment thickness 

and the occurrence of contaminants potentially toxic to 

benthic organisms. The thicknesses of impounded sediments 

were measured, and cores of sediment were collected from 

32 impoundments in 2004 and 2005. Cores were chemically 

analyzed, and concentrations of 32 inorganic elements and 

108 organic compounds were quantified. Sediment thicknesses 

varied considerably among the 32 impoundments, with 

an average thickness of 3.7 feet. Estimated volumes also 

varied greatly, ranging from 100,000 cubic feet to 81 million 

cubic feet. Concentrations of toxic contaminants as well 

as the number of contaminants detected above analytical 

quantification levels (also known as laboratory reporting 

levels) varied greatly among sampling locations. Based 

on measured contaminant concentrations and comparison 

to published screening thresholds, bottom sediments were 

predicted to be toxic to bottom-dwelling (benthic) organisms 

in slightly under 30 percent of the impoundments sampled. 

Statistically significant relations were found between several 

of the contaminants and individual indicators of urban land 

use and industrial activity in the upstream drainage areas of 

the impoundments. However, models developed to estimate 

contaminant concentrations at unsampled sites from upstream 

landscape characteristics had low predictive power, consistent 

with the long and complex land-use history that is typical of 

many drainage areas in Massachusetts.

Introduction

More than 3,000 dams presently impound the streams 

of Massachusetts, according to the Division of Ecological 

Restoration of the Massachusetts Department of Fish and 

Game (MDER, written commun., 2013). Nearly 1,500 of these 

dams are also listed in the National Inventory of Dams (U.S. 

Army Corps of Engineers, 1996). Worcester County, in central 

Massachusetts, has more dams than any other county in the 

United States (425; Graf, 1999). Because many Massachusetts 

dams no longer serve their original purposes, may present 

safety risks, and have the potential to impair ecological 

conditions, public interest in removing unused dams has 

grown substantially in recent years. Dams not only restrict the 

recreational use of rivers for boaters, they also limit or block 

the free passage of fish and other biota, slow water velocities, 

cause sediment and organic matter to settle out, and commonly 

raise water temperatures. This combination of factors affects 

water quality, impairs in-stream habitat, alters food web 

dynamics, and limits access to different habitats for resident 

and migratory fish (Wang and others, 2010; Armstrong and 

others, 2011). Dam removal can increase the amount of 

suitable aquatic habitat in a stream system, both upstream 

and downstream of the original structure, as well as restore 

ecological processes (for example, the natural movement of 

water, sediment, and organic matter) that form and maintain 

downstream habitat and food web dynamics over time (Poff 

and Hart, 2002; Gardner and others, 2011).

The purposeful breaching and removal of dams can have 

unintended effects on the downstream environment if not 

thoughtfully planned and implemented. One potential negative effect is the release of toxic contaminants by mobilization, 

transport, and downstream redeposition of impounded sediment. Many contaminants discharged to rivers and streams in 

the form of industrial wastes, accidental spills, or urban runoff 
2 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts

0 20 40 MILES

0 25 50 KILOMETERS

Base from U.S. Geological Survey digital data, 1:25:000, 1991

Lambert conformal conic projection. NAD 83

Location of dam

EXPLANATION

73° 72°

71°

70°

42°30'

41°30'

42°

Figure 1. The locations of dams in Massachusetts. Data are from the U.S. Army Corps of Engineers (1996).

commonly adhere to solids suspended in the water column of a 

stream and ultimately accumulate in slack water environments, 

such as impoundments behind dams. The accumulation of 

contaminated sediments behind dams in Massachusetts began 

principally after 1810, in the early years of the industrial revolution in the Commonwealth (Brown and Tager, 2000, p. 121). 

Urbanization in the latter part of the 19th century and throughout the 20th century further increased the load of contaminants 

from urban watershed sources to stream impoundments (see, 

for example, Breault and others, 2000, 2004, 2005).

Although contaminants trapped in sediment behind dams 

are often considered buried, it is incorrect to assume that these 

contaminants are immobile. For example, some contaminants 

are easily exchanged between bottom sediment and the overlying water column, allowing these contaminants to become 

biologically available under certain environmental conditions. 

Moreover, sediment-bound contaminants can be scoured, 

resuspended, transported downstream and redeposited during storm events, potentially affecting aquatic organisms, 

including fish, a long distance from the original source. Benthic organisms, which live on or within the bottom sediment, 

may be directly exposed to hazardous levels of these contaminants and, in turn, indirectly expose fish and other wildlife to 

the contaminants through food-web magnification. Humans 

may be exposed through ingestion of affected wildlife or by 

direct physical contact.

The Massachusetts Office of Dam Safety (ODS) requires 

regular safety inspections at dams under ODS jurisdiction. 

However, such inspections do not presently (2012) include 

estimates of the volume of impounded bottom sediment nor do 

they include the occurrence of potentially toxic contaminants 

trapped behind these dams. Hence, this aspect of the overall 

hazard associated with accidental dam failures or purposeful 

dam breaches is not fully known. Impounded sediment 

volumes and chemical data, together with information 

regarding the structural integrity of each dam, are necessary 

to inform decisions regarding potential dam removal projects 

in the Commonwealth. Accordingly, the U.S. Geological 
Field, Laboratory, and Statistical Methods 3

Survey (USGS), in cooperation with the MDER, collected 

baseline information concerning the thickness and volume of 

impounded bottom sediment and the occurrence of potentially 

toxic contaminants trapped behind 32 selected dams in 

Massachusetts. These data may be used to help prioritize dams 

that pose the greatest risk to the environment in case of either 

dam failure or purposeful dam breach, as well as identify 

sediment that may be acting as a present day source of toxic 

contaminants to the environment.

Purpose and Scope

This report describes the methods used to measure the 

thickness, estimate the volume, and collect cores of bottom 

sediment impounded behind selected dams in Massachusetts. 

The report also characterizes the chemical quality of the 

impounded sediment, including sediment-associated inorganic 

elements and organic compounds. The potential toxicity of 

the impounded sediment to benthic organisms is assessed 

by comparing observed concentrations of contaminants to 

consensus-based sediment quality guidelines. Finally, the 

report describes and interprets relations among contaminant 

concentrations in sediment, present day land use, and available 

indicators of past industrial history in the watersheds of the 

study impoundments.

Field, Laboratory, and Statistical 

Methods

The USGS assessed soft-sediment thicknesses and chemistry in 32 impoundments in Massachusetts by probing with 

a steel rod and collecting and chemically analyzing sediment 

cores. Chemical analysis of sediment cores (one homogenized 

sample per impoundment) included 32 inorganic elements 

and 108 organic compounds; the organic compounds included 

polycyclic aromatic hydrocarbons (PAHs), polychlorinated 

biphenyls (PCBs), and dichlorodiphenyl-trichloroethane 

(DDT) pesticide compounds. Potential toxicity was estimated 

using predictive relations between sediment contaminant 

concentrations and the probable effects on bottom-dwelling 

(benthic) organisms (Ingersoll and others, 2000; MacDonald 

and others, 2000). Relations between present day land use and 

sediment quality were evaluated by means of statistical correlation analysis.

Site Selection and Sampling Techniques

Dams were selected in consultation with the MDER using 

several criteria, including the likelihood that the dam might 

be removed, land use in the upstream drainage basin (ranging from undeveloped to drainage basins with long industrial 

histories), local interest, and geographical location (fig. 2; 

table 1).

Soft-sediment thicknesses were measured manually 

with a steel rod at an average of 20 locations in each of the 

32 impoundments; the number of measurements made in the 

study ranged from 8 to 30 per impoundment. The steel rod was 

pushed into the soft sediment from a boat or, in cases where 

impoundments were drained or dams breached, by standing on 

the sediment surface (fig. 3). Changes in the ease of penetration and the sound emitted from the rod as it was slowly 

pushed through the soft sediment were interpreted as changes 

in sediment character. In general, the interface between 

soft sediment and the original stream channel or flood plain 

material was felt as an abrupt change in the amount of force 

necessary to advance the probe. On occasion, this change was 

accompanied by an audible noise, as the tip of the rod encountered gravel or cobbles that were likely part of the historical 

flood plain or stream channel. The distance the rod was pushed 

(minus the measured water depth) was measured and recorded 

as the soft-sediment thickness. Sediment cores were visually inspected and their length was measured, to verify that 

soft-sediment thicknesses inferred from probing with the steel 

rod corresponded to changes in the sediment texture observed 

in cores from each impoundment in question. The average 

sediment thickness for an impoundment was calculated by 

summing the recorded depths and dividing by the number of 

measurements made in the impoundment.

At least one core was collected from each impoundment. 

The number and locations of cores collected was determined 

based on the size of each impoundment and the distribution 

of the estimated bottom-sediment thicknesses within each 

impoundment. Each core extended from the sediment water 

interface to the soft sediment bottom (to a maximum depth 

of about 8 ft). Cores were collected from a small boat, a 

custom-built pontoon boat and platform, or a solid platform 

placed directly on the sediment surface (fig. 4). Sediment 

was collected with a coring device comprising a polyethylene 

piston, a slide hammer, and a disposable polycarbonate core 

barrel. The core barrel was pushed by hand or hammered into 

the sediment. Before driving the core barrel into the sediment, 

the piston was suspended in the core barrel and secured with a 

steel cable to either the boat gunwale or the platform to keep 

the piston from moving as the core barrel was pushed into 

the sediment. Suction produced by the piston minimizes core 

compaction as the core barrel is pushed forward and helps to 

retain sediment in the barrel as it is pulled out of the sediment. 

Sediment cores were retrieved by hand or with a batterypowered winch.

In most cases, the core barrel was pushed past the softsediment bottom into the underlying material; however, in a 

few cases the soft-sediment thickness was greater than the core 

barrel length (8 ft). In these cases, the maximum core length 

was 8 ft. After retrieval, the bottom of each core was checked 

for evidence suggesting that the barrel was pushed deep 

enough to collect samples representative of the entire softsediment thickness. The end of the core barrel was frequently 

plugged with either fine gray clay, which was deposited long 

before the dam was built, or the remains of vegetation that 
4 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts

25

12

19

30

28

24

32

22

21

6

2

3 23

8

5 7

14

11

29

1

15

18

9

10

16

27

31

20

13

4

26

17

Base from U.S. Geological Survey digital data, 1:25:000, 1991

Lambert conformal conic projection. NAD 83

Location of impoundment and site identifier (see Table 1)

EXPLANATION

Drainage area contributing to impoundment

0 20 40 MILES

0 25 50 KILOMETERS

73° 72°

71°

70°

42°30'

41°30'

42°

Figure 2. Locations of impoundments in Massachusetts assessed in this study and the drainage areas to the dams that 

form the impoundments. Sites 24 and 31 are located less than 0.2 mile (mi) apart, and sites 20 and 27 are located less 

than 0.70 mi apart. Both pairs of sites are shown by a single red symbol. Location data are from the U.S. Army Corps of 

Engineers (1996).

presumably grew in the flood plain before inundation (fig. 5). 

If the core barrel appeared not to extend through the entire 

soft-sediment thickness and the total sediment thickness was 

less than 8 ft, the sample was discarded, the core barrel rinsed 

with ambient water, and another core was collected. It is 

important to note that core samples collected from individual 

impoundments may or may not represent the entire history 

of sediment deposition, given the limited number of core 

samples collected and the fact that only one composite sample 

was submitted for laboratory analyses. As stated above, the 

dynamic nature of sediment transport in river systems also 

means that some historically impounded sediment has likely 

been resuspended and transported downstream by large storms 

or dam breach or both. In some cases, sediment may have also 

been previously dredged and disposed of elsewhere during the 

history of the impoundment.

In the laboratory, cores from each impoundment were 

homogenized in a precleaned Teflon bag to produce one 

composite sample for each impoundment. Prior to filling, the 

Teflon bags were cleaned first with 5-percent hydrochloric 

acid, then with methanol, and finally with deionized water. 

Subsamples were collected and placed in precleaned plastic 

(inorganic elements) or glass (organic compounds) containers 

for delivery to appropriate analytical laboratories. Samples 

were shipped on ice in sealed plastic coolers along with 

accompanying documentation.

Chemical Analysis of Sediment

Chemical analysis of 32 inorganic elements was done 

at SGS Laboratory, Lakefield, Ontario, Canada, by means of 

inductively coupled plasma mass spectrometry (ICP–MS). 

Chemical analysis of 108 organic compounds was done at the 

USGS National Water Quality Laboratory (NWQL) in Denver, 

Colorado, by means of high-resolution gas chromatography/

low-resolution mass spectrometry (HRGC/LRMS).
Field, Laboratory, and Statistical Methods 

5

Table 1. Characteristics of selected dams in Massachusetts and sampling information for 2004 and 2005.[The State ID comprises [district number]-[county number]-[town number]-[dam number]. Dam latitude and longitude obtained from U.S. Army Corps of Engineers (2006), except for sites 31 and 32, which were determined in the field. Other dam data were obtained from the Massachusetts Office of Dam Safety database. no., number; NATID; national identification number; State ID, State identification number; USGS, U.S. Geological Survey; --, unknown]

Site 

no.

NATID State ID USGS station no. Latitude/longitude, in decimal degrees Dam name Year built1

Structural 

height, 

in feet

Town name County Stream name Major basin Sample date

1 MA00006 3-14-11-25 423744071532401 42.628747 -71.889712 Factory Village Pond 1924 20 Ashburnham Worcester Phillips Brook Nashua 06/21/052 MA00026 7-12-310-1 414554070445101 41.764962 -70.747216 Horseshoe Pond 1920 16 Wareham Plymouth Weweantic River Buzzards Bay 08/02/053 MA00057 2-6-312-7 424037072165001 42.676413 -72.280499 Sheomet Lake 1924 17 Warwick Franklin West Branch Tully 

River

Millers 07/14/05

4 MA00108 3-14-80-4 01125005 42.063413 -71.880131 North Webster Village 

Pond

1906 20 Dudley Worcester French River French 11/10/05

5 MA00154 5-5-9-8 423736071093001 42.627113 -71.157547 Ballardvale 1838 18 Andover Essex Shawsheen River Shawsheen 07/08/056 MA00216 3-14-80-1 420130071530501 42.024780 -71.884312 Perryville Pond 1874 18 Dudley Worcester French River French 05/17/047 MA00231 5-5-144-4 424037070501701 42.677648 -70.837756 Ipswich Mills 1900 9 Ipswich Essex Ipswich River Ipswich 09/08/058 MA00261 5-5-105-1 424403070594701 42.731749 -70.990537 Pentucket Pond Outlet 1850 8 Georgetown Essex Parker River Parker 07/13/059 MA00315 1-2-313-6 422142073132401 42.361564 -73.223409 Felton Lake 1937 15 Washington Berkshire Housatonic River Housatonic 11/08/05

10 MA00456 4-9-314-1 011046115 42.365362 -71.189229 Watertown 1900 8 Watertown Middlesex Charles River Charles 11/11/05

11 MA00463 2-6-68-1 423221072400201 42.538763 -72.667110 Conway Electric 1898 77 Conway Franklin South River Deerfield 09/01/05

12 MA00493 2-8-127-2 422208072362801 42.371453 -72.608327 D.F. Rile Grist Mill 1900 16 Hatfield Hampshire Mill River Connecticut 05/27/0413 MA00530 2-7-61-1 421135072350601 42.192920 -72.584950 Mountain Lake Dam 1923 36 Chicopee Hampden Willimansett Brook Connecticut 11/01/0514 MA00742 4-9-288-3 01098730 42.364608 -71.465922 Carding Mill Pond 1930 15 Sudbury Middlesex Hop Brook Sudbury 06/30/0515 MA00760 2-8-214-15 01171470 42.338019 -72.727849 Robert Meadow Upper 

Reservoir

1883 35 Northhampton Hampshire Roberts Meadow 

Brook

Connecticut 11/01/05

16 MA00774 4-9-31-1 01098980 42.591832 -71.283919 Talbot Mills 1850 12.5 Billerica Middlesex Concord River Concord 11/03/0517 MA00813 6-3-293-5 415528071062401 41.924374 -71.106524 Mill River 1832 12 Taunton Bristol Mill River Taunton 11/15/0518 MA00841 1-2-345-2 422919073063901 42.488376 -73.109927 Windsor Reservoir 1865 51 Windsor Berkshire Waconah Falls Brook Housatonic 11/08/0519 MA00877 3-14-97-11 423441071495601 42.578111 -71.830495 Mill Pond 1900 14 Fitchburg Worcester North Nashua River Nashua 06/17/0420 MA00909 7-12-239-8 011058739 41.946569 -70.673699 Mill Pond #1 1900 16 Plymouth Plymouth Town Brook South Coastal 11/15/0521 MA00935 3-14-304-4 420610071372201 42.098145 -71.623096 Rice City Pond 1880 21 Uxbridge Worcester Blackstone River Blackstone 06/09/0422 MA00995 3-14-215-4 421944071374801 42.329712 -71.630020 Assabet River 1900 12 Northborough Worcester Assabet River Concord 05/20/0423 MA01001 4-9-301-5 424030071253401 42.674801 -71.426043 Upper Flints Pond 1900 10 Tyngsborough Middlesex Unnamed tributary to 

Merrimack River

Merrimack 07/07/05

24 MA01572 4-9-157-4 422406071182801 42.401599 -71.307854 Stony Brook 1900 10 Lincoln Middlesex Stony Brook Charles 06/16/0425 MA01970 1-2-236-11 422651073155001 42.446875 -73.263670 Tel Electric Pond 1920 20 Pittsfield Berkshire West Branch Housatonic Housatonic 05/26/0426 MA02116 6-3-102-2 01109088 41.798038 -71.063516 Monument Pond #2 1900 -- Freetown Bristol Assonet River Taunton 11/17/0527 MA02458 7-12-239-7 415656070402701 41.949048 -70.673844 Town Brook #1 1900 11 Plymouth Plymouth Town Brook South Coastal 07/21/0528 MA02512 5-5-9-17 423704071063701 42.616993 -71.110105 Deleano Pond 1930 14 North Andover Essex Unnamed tributary to 

Skug

Ipswich 05/19/04

29 MA02828 3-14-186-1 421127071445202 42.190776 -71.747510 Worcester Consolidated 

Station

1900 6 Millbury Worcester Blackstone River Blackstone 06/22/05

30 MA03175 3-14-21-21b 422440072061201 42.411263 -72.102398 Cooks Canyon Lower 

Pond

1900 15 Barre Worcester Galloway Brook Chicopee 06/10/04

31 -- -- 422358071182601 42.399460 -71.307113 Unnamed, Stony Brook 1900 -- Weston Middlesex Stony Brook Charles 06/16/0432 -- -- 415638070485101 41.944083 -70.815004 Unnamed, Winnetuxet 

River

1900 -- Plympton Plymouth Winnetuxet River Taunton 06/21/04

1The year 1900 is typically assigned to dams for which the actual year of construction is unknown (Brian Graber, Massachusetts Riverways Program, oral commun., 2005).
6 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts

A

B

Figure 3. Measurement of soft-sediment thickness where A,

dam has been breached and the impoundment has been drained 

and B, impoundment is present at the time of sampling.

Analysis of Inorganic Elements

Before chemical analysis, SGS collected from each 

sample an unsieved aliquot (about 1 gram). Next, the sample 

was digested with 2 milliliters (mL) of nitric acid (HNO3

) 

and heated at 80 to 90 degrees Celsius for 1⁄2 hour. After the 

sample had cooled slightly, the digestates were spiked with 

4 mL of hydrochloric acid (HCl) and heated for 2 hours in a 

water bath. Next, the digestates were allowed to cool to room 

temperature and diluted with distilled water to a final volume 

of 20 mL. About 5 mL of this solution was poured into a test 

tube for ICP–MS analysis (U.S. Environmental Protection 

Agency, 1996).

Environmental samples were analyzed by SGS in batches 

of up to 40 samples. Each batch was accompanied by quality 

assurance/quality control (QA/QC) samples—including procedural blanks, laboratory duplicates, matrix-spike samples, 

and recovery standards—to test laboratory bias and variability. 

Before analytical results were accepted, QA/QC samples had 

to meet the following methodology criteria: inorganic element 

concentrations measured in procedural blanks were required to 

be less than quantification limits; relative percentage differences (RPDs) between laboratory duplicate and matrix-spike 

samples were no more than 10 percent; and percent recoveries 

were within the 50 to 100 percent range. Laboratory instruments were calibrated in accordance with the standard operating procedures of SGS and were required to meet method 

specifications (SGS Laboratory, written commun., 2006).

Organic Analysis

The day before the chemical analysis, the USGS laboratory extracted unsieved sediment overnight with dichloromethane in a Soxhlet apparatus and split into two aliquots 

(Foreman and others, 1995; Furlong and others, 1996). The 

first aliquot was analyzed for PAHs and alkyl-PAHs by capillary column gas chromatography with detection by mass 

spectrometry (Furlong and others, 1996). The second aliquot 

was analyzed for chlorinated hydrocarbons by dual capillary 

column gas chromatography with electron capture detection 

(Noriega and others, 2004).

Environmental samples were analyzed at the USGS 

National Water Quality Laboratory (NWQL) in batches of 

up to 12 samples. Each batch was accompanied by QA/QC 

samples—including procedural blanks, laboratory duplicates, 

matrix-spike samples, and recovery standards—to test 

laboratory bias and variability (Noriega and others, 2004). 

Before analytical results were accepted, QA/QC samples 

had to meet the following methodology criteria: chemical 

concentrations measured in procedural blanks were less than 

quantification limits; RPDs between laboratory duplicate 

and matrix-spike samples were no more than 10 percent; 

and percent recovery ranges were within 50 to 120 percent. 

Laboratory instruments were calibrated in accordance with the 

standard operating procedures of the USGS and were required 

to meet method specifications.
Field, Laboratory, and Statistical Methods 7

A

B

pontoon or B, at the sediment surface where the impoundment has been drained.

Figure 4. Methods used to obtain cores from impoundments. Cores were collected A, from floating 
8 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts

A

B

Figure 5. Examples of core penetration through the full thickness of impounded sediment into 

preimpoundment material. Core samples contain A, floodplain vegetation, and B, inorganic clay.
Field, Laboratory, and Statistical Methods 9

Bias and Variability in Field and Laboratory 

Analyses

Environmental samples were collected and analyzed 

along with field duplicates (or split samples) and blind reference samples. These QA/QC samples were collected, processed, and analyzed in exactly the same way as the environmental samples. Therefore, the field QA/QC samples can be 

used to assess bias and variability associated with environmental conditions, sample collection, and sample processing 

as well as with laboratory processing. Field duplicates were 

collected at 3 of 32 locations and consisted of two representative aliquots of sediment that were taken from the homogenized sample and were analyzed separately. RPDs for detectable inorganic element concentrations between field duplicate 

samples averaged 2.9 percent, with one exception. The RPD 

for detectable molybdenum concentration measured in the 

Mountain Lake impoundment field duplicate sample (site 13) 

was 66 percent. Blind reference samples for the inorganic elements, consisting of National Institute of Standards and 

Technology (NIST) standard reference material (SRM) 2711 

Montana Soil, were submitted to SGS for analysis. RPDs 

between the SGS-reported inorganic element concentrations 

and the NIST-certified values for the blind samples were all 

less than 15 percent, with the exception of that for titanium, 

which had an RPD of about 28 percent. Field duplicate 

samples were not analyzed for organic compounds.

Quality assurance for organic constituents was conducted 

at the NWQL. No blind reference samples were submitted to 

NWQL. However, percent recovery of laboratory surrogate 

organic constituents ranged between 30 and 95 percent, and 

RPDs between sample and replicate results were less than 

25 percent for 103 of the 115 constituents investigated for two 

of the replicate sample pairs and less than 25 percent for 88 

of the constituents for the third replicate sample pair. Average 

and median RPDs between all replicate sample pairs were 18 

and 6 percent, respectively.

Concentrations of inorganic elements and organic 

compounds greater than the detection limit indicate that the 

compound concentration is greater than the laboratory reporting level (LRL) for a given analytical technique. Nondetection may indicate either that the compound is not present in 

the sample or that the concentration of the compound in the 

sample is less than the LRL for the analytical technique used. 

The LRL is generally equal to twice the long-term method 

detection limit (LT–MDL) for a given analyte and laboratory 

method (Childress and others, 1999).

Estimated Toxicity of Sediment

The consensus-based sediment quality guidelines 

(Ingersoll and others, 2000; MacDonald and others, 2000) 

were used in this study to compare impounded-sediment 

chemistry results to predicted impacts on benthic dwelling 

organisms. It is important to note that these guidelines are 

empirical, effects-based thresholds derived from laboratory 

toxicology tests on a limited range of organisms. As such, the 

thresholds do not account for chronic toxicity that results from 

prolonged exposure, toxicity caused by mixtures of chemicals, 

nor to biological availability of contaminants or other mortality drivers that may be governed by environmental conditions. 

For example, high sediment-oxygen demand (SOD) may 

result in low dissolved oxygen (DO) concentrations that can 

be lethal to some aquatic organisms; by contrast, acid-volatile 

sulfides (AVS) may chemically bind some toxic chemicals 

making them biologically immobile.

Nevertheless, estimation of sediment toxicity from 

concentrations of common contaminants and known 

threshold effect concentrations (TECs) and probable effect 

concentrations (PECs) has been shown to be a reasonable 

predictor of toxicity in a laboratory setting for a limited range 

of organisms (Ingersoll and others, 2000; MacDonald and 

others, 2000). The TEC for a given contaminant is defined as 

the concentration below which harmful effects are unlikely 

to be observed, and the PEC is defined as the concentration 

above which effects are likely to be observed (MacDonald and 

others, 2000).

Understanding of potential sediment toxicity is facilitated 

by determination of PEC quotients (PECQs) for individual 

contaminants within a sample (MacDonald and others, 2000). 

The PECQ is defined as the ratio of the concentration of a 

contaminant in a sample to the contaminant PEC. To obtain 

an estimate of the overall toxicity of a sediment sample x, 

the PECQs for the individual contaminants (and contaminant 

groups) in a sample are averaged to obtain the overall sample 

PECQ, also known as the PECQx

, as follows:

PECQ

C

PEC

n x

x y

y

x

=

∑ ,

, (1)

where

PECQx is the average PECQ for sediment sample x,

Cx,y is the concentration of contaminant y or 

contaminant group y in sample x,

PECy is the PEC for chemical y (MacDonald and 

others (2000), and

nx is the number of contaminants or contaminant 

groups used in sample x.

Before calculating the PECQx

, the contaminant concentrations 

are first adjusted for censored data (data below the laboratory 

reporting level). In accordance with the practice of Breault 

and others (2005, p. 10), censored data were set equal to zero 

in the calculation of the PECQ and PECQx

 values. Consequently, our approach to the calculation of PECQx

 for a sample 

does not include any toxicity associated with undetected 

constituents.
10 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts

In the current study, 10 PECQs (for arsenic, cadmium, 

chromium, copper, lead, nickel, and zinc, total PAHs, total 

PCBs, and total DDTs) were averaged to determine a PECQx

for each sample. For the purposes of this report, total PAHs 

equal the sum of anthracene, benzo(a)anthracene, benzo(a)

pyrene, chrysene, 9H-fluorene, fluoranthene, naphthalene, 

phenanthrene, and pyrene; total PCBs equal the sum of all 

polychlorinated biphenyl congeners; and total DDTs equal the 

sum of ortho,para’-DDE, para,para’-DDE, ortho,para’-DDD, 

para,para’-DDD, ortho,para’-DDT, and para,para’-DDT.

The probability of observing sediment toxicity in a 

sample may be estimated from the PECQx

 using the following 

equation (MacDonald and others, 2000):

not be calculated for these three sites. At all other sites, surface 

areas reported in the NID for each impoundment (U.S. Army 

Corps of Engineers, 1996) were multiplied by average thicknesses to give planning-level estimates of sediment volumes 

(table 2). Sediment volumes estimated in this manner ranged 

from 110,000 ft3

 (Deleano Pond Dam on an unnamed tributary 

of the Skug River in North Andover, site 28) to 81 million 

cubic feet (Mft3

; Talbot Mills Dam on the Concord River in 

Billerica, site 16). It is important to note that sediment may not 

accumulate in a uniform manner behind a dam; commonly it 

forms a wedge shape based upon the gradual settling of different grain sizes in response to reduced water velocities within 

an impoundment. Therefore, actual volumes of impoundment 

sediment may be greater or less than the estimated volumes 

presented here.

Concentrations of Inorganic Elements

Contaminant concentrations in the sediment cores (inorganic elements and organic compounds) varied substantially 

among impoundments. Many of these contaminants are on the 

U.S. Environmental Protection Agency list of 126 priority pollutants (U.S. Environmental Protection Agency, undated). The 

priority pollutant elements arsenic, chromium, copper, lead, 

nickel, and zinc were detected at all 32 impoundment sites. 

The priority pollutant element cadmium was detected at 14 of 

the 32 sites.

The highest concentrations of the inorganic elements 

copper, nickel, and zinc were measured at the Worcester 

Consolidated Station Dam (site 29) on the Blackstone River 

in Millbury (fig. 6; table 3). This finding is consistent with the 

long industrial history of the Blackstone River and its watershed, which, together with the Charles River, is considered 

the birthplace of the industrial revolution in Massachusetts 

(Brown and Tager, 2000, p. 121). Among the 32 impoundment 

sites, the highest concentrations of the inorganic elements 

arsenic, cadmium, chromium, and lead were measured at the 

Mill Pond Dam #1 on the Town Brook in Plymouth (site 20), 

the Mill Pond Dam on the North Nashua River in Fitchburg 

(site 19), the Perryville Pond Dam on the French River in 

Dudley (site 6), and the Tel Electric Pond Dam on the West 

Branch Housatonic in Pittsfield (site 25), respectively. The 

Rice City Pond Dam on the Blackstone River in Uxbridge 

(site 21) also had relatively higher concentrations of the priority pollutant elements than most other sites, with the second 

highest concentrations of cadmium, chromium, copper, and 

nickel and the third highest concentrations of lead and zinc 

among the 32 sites (fig. 6).

Y x = × 101 48 . . ( ) 1 0 − 36

where

Y is the estimated probability of toxicity, in 

percent; and

x is the average probable effects quotient for 

a sample (PECQx

); as calculated in 

equation 1.

(2)

Sediment Thickness, Chemical Quality, 

and Estimated Toxicity

The thickness, chemical quality, and estimated toxicity 

of bottom sediment were assessed at each of the 32 impoundments selected for this study. Major results are presented in the 

following sections.

Measured Sediment Thicknesses and Estimated 

Volumes

Average sediment thicknesses ranged from 0.5 to 6.7 ft 

among the impoundments, with an overall average of 3.7 ft 

(table 2). Minimum sediment thicknesses ranged from 0 to 

2.6 ft. The maximum measured sediment thickness was about 

15 ft (D.F. Rile Grist Mill Dam, site 12). At the Conway 

Electric Dam on the South River in Conway (site 11), sediment thicknesses were found to be greater than what could be 

feasibly measured with a steel rod (greater than 20 ft). At the 

Pentucket Pond Outlet and Carding Mill Dams (sites 8 and 

14), local field conditions precluded collection of thickness 

data. For these reasons, estimates of sediment volume could 
Sediment Thickness, Chemical Quality, and Estimated Toxicity 11

Table 2. Bottom-sediment thicknesses and estimated volumes of sampled impoundments in Massachusetts in 2004 and 2005.

[Estimated sediment volumes are rounded values. no., number; ft, feet; ft2, square feet; ft3, cubic feet; --, not sampled]

Site 

no.

Dam

Estimated 

surface 

area, 

in ft2

Average 

water 

depth, 

in ft

Average 

sediment 

thickness, 

in ft

Minimum 

sediment 

thickness, 

in ft

Maximum 

sediment 

thickness, 

in ft

Number 

of measurements

Estimated 

sediment 

volume, 

in ft3

Number of 

sediment 

cores collected

1 Factory Village Pond 220,000 6.2 3.4 1.1 7.0 29 750,000 4

2 Horseshoe Pond 2,600,000 1.6 4.4 1.9 6.1 16 12,000,000 2

3 Sheomet Lake 1,300,000 6.9 2.5 0.0 4.2 24 3,200,000 2

4 North Webster Village Pond 3,700,000 4.4 4.5 0.0 7.8 15 17,000,000 5

5 Ballardvale 1,600,000 2.3 3.3 0.0 5.1 23 5,200,000 5

6 Perryville Pond1 1,100,000 3.0 4.5 2.5 9.5 50 1,917,000 3

7 Ipswich Mills 1,300,000 4.1 3.3 0.0 8.5 27 4,300,000 2

8 Pentucket Pond Outlet2 4,000,000 -- -- -- -- -- -- 4

9 Felton Lake 540,000 7.0 2.8 0.1 5.5 15 1,500,000 1

10 Watertown 630,000 5.0 1.5 0.0 5.2 17 950,000 3

11 Conway Electric3 98,700 -- -- -- -- -- -- 2

12 D.F. Rile Grist Mill 770,000 8.5 5.0 0.0 15.0 18 3,900,000 7

13 Mountain Lake 460,000 (4) 6.4 1.5 9.3 21 2,900,000 2

14 Carding Mill Pond2 1,800,000 -- -- -- -- -- -- 3

15 Robert Meadow Upper Reservoir 240,000 8.6 6.7 1.4 10.6 19 1,600,000 2

16 Talbot Mills 22,000,000 9.3 3.7 0.0 8.0 12 81,000,000 3

17 Mill River 870,000 2.5 4.8 2.6 7.2 11 4,200,000 2

18 Windsor Reservoir 3,200,000 (4) 4.0 0.3 8.0 26 13,000,000 2

19 Mill Pond 200,000 3.1 3.3 0.0 9.6 26 660,000 2

20 Mill Pond #1 40,800 2.5 4.8 2.6 7.2 11 200,000 1

21 Rice City Pond 940,000 1.3 5.4 0.3 8.1 8 5,000,000 6

22 Assabet River5 210,000 1.5 4.5 0.3 11.0 140 1,483,200 3

23 Upper Flints Pond 3,100,000 4.9 1.7 0.6 4.0 21 5,400,000 3

24 Stony Brook 59,800 2.5 2.0 0.6 3.8 23 120,000 3

25 Tel Electric Pond 610,000 4.3 3.4 0.0 6.5 21 2,000,000 3

26 Monument Pond #2 320,000 4.7 2.4 1.4 4.4 18 770,000 3

27 Town Brook #1 50,500 1.8 3.4 0.8 4.9 16 170,000 3

28 Deleano Pond 220,000 4.0 0.5 0.0 1.8 27 110,000 7

29 Worcester Consolidated Station 2,400,000 3.2 4.0 1.0 6.7 30 9,600,000 4

30 Cooks Canyon Lower Pond 30,800 2.5 5.1 0.3 11.4 25 160,000 2

31 Unnamed, Stony Brook 120,000 2.5 2.0 0.6 3.8 23 240,000 3

32 Unnamed, Winnetuxet River 17,200 2.3 3.2 0.2 5.7 25 55,000 2

1

Data from Zimmerman and Breault (2003).

2

Field conditions precluded measurement.

3

Thickness greater than 20 ft probe length.

4

Impoundment was dry at time of measurement.

5

Data from Zimmerman and Sorenson (2005).
12 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts

0 5 10 15 20

8754

1332313028272624232018171615131211

61

2522

1

25

932

1921291014

0 10 20 30 40

2617151211

93

301828

754

2313

6

24162219103214252513

2

29273121

118

20

A

B

Site number

Site number

Arsenic, in parts per million Cadmium, in parts per million

Figure 6. Concentrations of A, arsenic, B, cadmium, C, chromium, D, copper, E, lead, F, nickel, and G, zinc in sediment samples from 32 impoundments in Massachusetts. Blue 

dashed line shows threshold effects concentration (TEC), and the red dashed line shows probable effects concentration (PEC; MacDonald and others, 2000). The laboratory reporting level (LRL) for cadmium coincides with the threshold effects concentration (1 ppm) on part B. LRLs are not shown for the remaining elements, because all other elements were found above the respective LRLs at all sites. Concentrations of field duplicate samples (table 3) are plotted for sites 1, 13, and 25. Site locations are listed in 

table 1.
Sediment Thickness, Chemical Quality, and Estimated Toxicity 13

0 50 100 150 200 250

3217

9

30202628

211

141223

87

3124

5

131318

3

221611191015

4

2127252925

6

0 100 200 300 400

75

2632

9

181712

8

2430281513131123

32

31

114

2519251427162010

6

292122

C

D

Site number

Site number

Chromium, in parts per million Copper, in parts per million

Figure 6. Concentrations of A, arsenic, B, cadmium, C, chromium, D, copper, E, lead, F, nickel, and G, zinc in sediment samples from 32 impoundments in Massachusetts. Blue 

dashed line shows threshold effects concentration (TEC), and the red dashed line shows probable effects concentration (PEC; MacDonald and others, 2000). The laboratory reporting level (LRL) for cadmium coincides with the threshold effects concentration (1 ppm) on part B. LRLs are not shown for the remaining elements, because all other elements were found above the respective LRLs at all sites. Concentrations of field duplicate samples (table 3) are plotted for sites 1, 13, and 25. Site locations are listed in 

table 1.—Continued
14 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts 0 50 100 150 200 250 300

8

11322812181726

95

23

7

3115

243

20141313302416

6

1022

11

252519212729

E F 

0 60

Site number

10 20 30 40 50

Site number

Lead, in parts per million Nickel, in parts per million

9

2823322617

4

30

72

20

651

19

1

252522151114312427101612131813

83

2921

Figure 6. Concentrations of A, arsenic, B, cadmium, C, chromium, D, copper, E, lead, F, nickel, and G, zinc in sediment samples from 32 impoundments in Massachusetts. Blue 

dashed line shows threshold effects concentration (TEC), and the red dashed line shows probable effects concentration (PEC; MacDonald and others, 2000). The laboratory reporting level (LRL) for cadmium coincides with the threshold effects concentration (1 ppm) on part B. LRLs are not shown for the remaining elements, because all other elements were found above the respective LRLs at all sites. Concentrations of field duplicate samples (table 3) are plotted for sites 1, 13, and 25. Site locations are listed in 

table 1.—Continued
Sediment Thickness, Chemical Quality, and Estimated Toxicity 15

0 100 200 300 400 500

G

Site number

Zinc, in parts per million

3226231728

74

31131330181112

89

2716242015

5

191014

2311

22

6

29252125

Figure 6. Concentrations of A, arsenic, B, cadmium, C, chromium, D, copper, E, lead, 

F, nickel, and G, zinc in sediment samples from 32 impoundments in Massachusetts. Blue dashed line shows threshold effects concentration (TEC), and the red dashed line shows probable effects concentration (PEC; MacDonald and others, 2000). The laboratory reporting level (LRL) for cadmium coincides with the threshold effects concentration (1 ppm) on part B. LRLs are not shown for the remaining elements, because all other elements were found above the respective LRLs at all sites. Concentrations of field duplicate samples (table 3) are plotted for sites 1, 13, and 25. Site locations are listed in table 1.—Continued
16 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts

Table 3. Concentrations of inorganic elements measured in bottom-sediment cores collected from selected impoundments in 

Massachusetts in 2004 and 2005.

[Concentrations were determined on unmilled samples using method 3050b digestion from U.S. Environmental Protection Agency (1996). DUP, field duplicate 

sample; no., number; ppm, parts per million; %, percent; <, less than value shown]

Site 

no.

Dam name

Berylllium,

in ppm

Sodium,

in %

Magnesium,

in %

Aluminum,

in %

Phosphorus,

in %

Potassium,

in %

Calcium,

in %

Scandium,

in ppm

Titanium,

in %

Vanadium,

in ppm

1 Factory Village Pond 4.2 1.08 0.28 5.91 0.15 2.19 0.6 5.3 0.2 46

2 Horseshoe Pond 1.5 0.89 0.2 3.73 0.1 1.06 0.56 4.3 0.19 54

3 Sheomet Lake 1.9 0.8 0.58 5.46 0.12 0.85 0.87 10 0.29 94

4 North Webster Village Pond 2.1 1.12 0.3 4.75 0.04 1.48 0.99 3.9 0.16 27

5 Ballardvale 2.4 1.11 0.36 4.73 0.05 1.51 1.01 4.6 0.18 36

6 Perryville Pond 2.2 1.1 0.31 4.57 0.07 1.5 0.93 4.2 0.16 33

7 Ipswich Mills 1.7 1.36 0.39 4.82 0.03 1.73 0.76 4 0.12 36

8 Pentucket Pond Outlet 1.2 0.44 0.33 2.4 0.05 0.52 1.18 3.3 0.08 31

9 Felton Lake 1.7 0.99 0.28 4.54 0.23 0.86 1.22 9.2 0.51 37

10 Watertown 1.8 1.36 0.68 5.47 0.09 1.66 1.26 7.8 0.33 78

11 Conway Electric 1.9 1 1 6.15 0.06 1.22 1.42 15.3 0.3 93

12 D.F. Rile Grist Mill 1.6 1.43 0.67 5.62 0.05 1.22 1.27 9.8 0.28 70

13 Mountain Lake 2.1 1.53 0.55 6.39 0.1 1.66 1.32 8 0.3 68

14 Carding Mill Pond 2.4 0.78 0.26 3.73 0.25 0.88 1.32 4.7 0.16 36

15 Robert Meadow Upper Reservoir 2.9 1.12 0.56 6.45 0.09 1.52 1.12 9.8 0.31 83

16 Talbot Mills 1.9 0.97 0.25 4.02 0.1 1.3 0.98 3.6 0.1 30

17 Mill River 1.5 1.45 0.25 4.57 0.03 1.6 0.83 4.3 0.21 36

18 Windsor Reservoir 1.5 0.87 0.64 5.48 0.07 2.17 0.84 7.3 0.28 61

19 Mill Pond 2.7 1.05 0.24 7.07 0.07 1.58 0.67 5.4 0.45 50

20 Mill Pond #1 1.5 0.6 0.22 2.84 0.07 0.88 0.41 3.3 0.14 42

21 Rice City Pond 1.9 1.08 0.36 4.71 0.18 1.54 0.8 4.9 0.21 43

22 Assabet River 2.1 1.19 0.62 5.53 0.14 1.27 1.22 8 0.25 63

23 Upper Flints Pond 2.2 1.14 0.21 4.18 0.06 1.47 0.87 3.3 0.14 21

24 Stony Brook 1.6 0.81 0.48 4.05 0.11 0.89 1.31 5.7 0.2 61

25 Tel Electric Pond 1.5 0.56 1.66 5.18 0.08 1.71 2.52 7.9 0.18 66

26 Monument Pond #2 1.4 0.85 0.25 3.58 0.03 1.12 0.43 3.4 0.15 34

27 Town Brook #1 2.1 0.61 0.2 3.67 0.06 0.97 0.38 5.3 0.18 54

28 Deleano Pond 1.9 0.17 0.16 1.41 0.15 0.15 1.05 5.5 0.05 14

29 Worcester Consolidated Station 1.9 1.05 0.42 5.25 0.12 1.77 0.84 5.6 0.23 49

30 Cooks Canyon Lower Pond 2.8 1.65 0.33 6.12 0.18 1.67 1.67 5.3 0.35 46

31 Unnamed, Stony Brook 1.3 0.79 0.37 3.64 0.1 0.79 1.11 4.5 0.17 49

32 Unnamed, Winnetuxet 0.9 0.7 0.15 2.61 0.03 0.96 0.32 2.3 0.14 25

1 DUP-Factory Village Pond 4 1.09 0.28 5.95 0.15 2.21 0.61 5.2 0.2 47

13 DUP-Mountain Lake 2.2 1.51 0.56 6.37 0.1 1.65 1.34 8.1 0.3 70

25 DUP-Tel Electric Pond 1.5 0.57 1.63 5.21 0.08 1.71 2.46 8 0.18 68
Sediment Thickness, Chemical Quality, and Estimated Toxicity 17

Table 3. Concentrations of inorganic elements measured in bottom-sediment cores collected from selected impoundments in 

Massachusetts in 2004 and 2005.—Continued

[Concentrations were determined on unmilled samples using method 3050b digestion from U.S. Environmental Protection Agency (1996). DUP, field duplicate 

sample; no., number; ppm, parts per million; %, percent; <, less than value shown]

Site 

no.

Dam name

Chromium,

in ppm

Manganese,

in ppm

Iron,

in %

Cobalt,

in ppm

Nickel,

in ppm

Copper,

in ppm

Zinc,

in ppm

Arsenic,

in ppm

Strontium,

in ppm

Yttrium,

in ppm

Zirconium,

in ppm

1 Factory Village Pond 32 472 2.25 9 13 36.5 213 24 111 10.9 35.7

2 Horseshoe Pond 33 546 2.97 8 11 25.1 250 15 95.2 17.1 57.1

3 Sheomet Lake 53 602 3.64 17 28 26 216 4 80.9 17.3 37

4 North Webster Village Pond 91 297 1.23 3 10 35.9 51.8 6 137 10.5 38

5 Ballardvale 43 379 1.55 6 13 7.9 149 7 121 11.9 47.7

6 Perryville Pond 196 377 1.69 5 13 109 293 8 130 10.4 43.7

7 Ipswich Mills 37 372 2.08 5 11 9.9 59.2 7 120 7.4 32

8 Pentucket Pond Outlet 42 702 3.24 12 28 17.2 112 23 67.3 13 21.4

9 Felton Lake 22 285 1.89 4 6 11.2 105 4 96.1 54.7 28.4

10 Watertown 60 581 3.23 8 17 42.5 197 10 162 15.7 56.2

11 Conway Electric 63 1,310 4.27 8 22 17.6 72.2 3 150 23.7 30.8

12 D.F. Rile Grist Mill 35 681 2.86 8 16 11.2 68.2 3 149 19.1 28.2

13 Mountain Lake 50 577 3.67 7 15 20.7 91.4 8 238 16.5 32.7

14 Carding Mill Pond 35 469 2 10 21 63.6 191 9 125 21.5 34.6

15 Robert Meadow Upper Reservoir 58 789 3.32 8 22 21.2 116 3 152 18.1 50.1

16 Talbot Mills 77 451 1.74 12 16 50.6 143 13 123 10.7 22.6

17 Mill River 19 430 1.63 3 8 12.5 32 3 146 11.9 39.4

18 Windsor Reservoir 43 539 3.24 9 15 14.5 85.1 5 128 15.2 59.8

19 Mill Pond 60 360 1.79 7 14 75.3 204 11 160 10.4 41.7

20 Mill Pond #1 31 447 2.06 5 11 48.7 120 37 64.3 11.5 37.3

21 Rice City Pond 158 561 2.8 5 29 223 296 15 138 11.5 66.2

22 Assabet River 82 557 2.5 11 22 155 278 12 163 14.4 45.6

23 Upper Flints Pond 33 419 1.26 3 9 17.2 34.1 7 133 9.2 27.3

24 Stony Brook 42 650 2.68 11 18 25 132 14 113 11.7 40.3

25 Tel Electric Pond 103 805 3.69 11 25 69.8 293 8 79.3 12.3 56.8

26 Monument Pond #2 25 271 1.61 4 8 10.7 35.1 3 82.8 8.2 44.4

27 Town Brook #1 155 266 1.99 7 17 57.9 143 19 96.5 13.6 52.5

28 Deleano Pond 24 154 0.61 2 9 22.7 21 4 71.7 17.8 10.3

29 Worcester Consolidated Station 103 537 3.78 6 36 376 325 21 155 12.4 57.6

30 Cooks Canyon Lower Pond 31 468 1.83 6 10 23.6 88.4 5 454 17.4 24.7

31 Unnamed, Stony Brook 42 907 2.97 12 18 26.6 104 16 96.5 11.4 37.1

32 Unnamed, Winnetuxet 19 347 1.84 6 8 10.4 46.7 9 71.5 6.8 33.1

1 DUP-Factory Village Pond 32 470 2.27 9 14 39.5 212 25 111 11.5 36

13 DUP-Mountain Lake 50 573 3.81 7 15 20.5 94.1 7 236 16.4 32.9

25 DUP-Tel Electric Pond 111 792 3.69 11 26 75.7 300 8 79.9 13.1 59.2
18 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts

Table 3. Concentrations of inorganic elements measured in bottom-sediment cores collected from selected impoundments in 

Massachusetts in 2004 and 2005.—Continued

[Concentrations were determined on unmilled samples using method 3050b digestion from U.S. Environmental Protection Agency (1996). DUP, field duplicate 

sample; no., number; ppm, parts per million; %, percent; <, less than value shown]

Site 

no.

Dam name

Molybdenum,

in ppm

Silver,

in ppm

Cadmium,

in ppm

Tin,

in ppm

Antimony,

in ppm

Barium,

in ppm

Lanthanum,

in ppm

Tungsten,

in ppm

Lead,

in 

ppm

Bismuth,

in ppm

Lithium,

in ppm

1 Factory Village Pond <1 <2 1 10 <5 479 27.4 <10 153 <5 32

2 Horseshoe Pond 2 <2 2 <10 <5 321 25.6 <10 49 <5 11

3 Sheomet Lake 2 <2 2 <10 <5 336 24.6 <10 46 <5 24

4 North Webster Village Pond <1 <2 <1 40 <5 336 21.6 <10 47 <5 17

5 Ballardvale <1 <2 <1 <10 <5 343 19.8 <10 26 <5 19

6 Perryville Pond <1 <2 1 20 <5 323 20.3 <10 104 <5 18

7 Ipswich Mills <1 <2 <1 <10 <5 346 14.6 <10 32 <5 18

8 Pentucket Pond Outlet 2 <2 <1 <10 <5 143 17.2 <10 13 <5 13

9 Felton Lake 1 <2 2 <10 <5 327 60.8 <10 29 <5 16

10 Watertown 2 <2 4 <10 7 440 24.7 <10 142 <5 16

11 Conway Electric <1 <2 <1 <10 <5 363 24.8 <10 20 <5 40

12 D.F. Rile Grist Mill <1 <2 <1 <10 <5 381 24.9 <10 17 <5 23

13 Mountain Lake 1 5 <1 <10 6 582 43.7 <10 82 <5 14

14 Carding Mill Pond 3 <2 2 <10 <5 291 34.5 <10 85 <5 17

15 Robert Meadow Upper Reservoir 1 <2 <1 <10 <5 404 35.3 <10 37 <5 59

16 Talbot Mills 1 <2 <1 <10 <5 329 16.8 <10 63 <5 13

17 Mill River <1 <2 <1 <10 <5 466 18.2 <10 16 <5 9

18 Windsor Reservoir <1 <2 <1 <10 <5 501 31.1 <10 16 <5 19

19 Mill Pond 2 <2 19 20 20 531 26 <10 205 <5 30

20 Mill Pond #1 2 <2 <1 <10 <5 304 18.7 <10 93 <5 10

21 Rice City Pond 2 2 11 60 <5 451 25.4 30 174 <5 20

22 Assabet River 2 2 1 20 <5 438 27.6 <10 110 <5 25

23 Upper Flints Pond 1 <2 <1 <10 <5 383 16.7 <10 29 <5 13

24 Stony Brook 2 <2 <1 <10 <5 318 21.1 <10 67 <5 23

25 Tel Electric Pond 1 <2 1 <10 <5 420 25.9 <10 241 <5 36

26 Monument Pond #2 <1 <2 <1 <10 <5 329 14.1 <10 15 <5 13

27 Town Brook #1 2 <2 <1 40 <5 344 21.6 <10 164 <5 23

28 Deleano Pond 4 <2 <1 <10 <5 77 23.2 <10 18 <5 5

29 Worcester Consolidated Station 1 <2 9 60 7 468 29.5 <10 156 <5 27

30 Cooks Canyon Lower Pond <1 <2 <1 <10 <5 862 45.3 <10 77 <5 10

31 Unnamed, Stony Brook 2 <2 <1 <10 <5 296 21.6 <10 45 <5 21

32 Unnamed, Winnetuxet 2 <2 <1 <10 <5 307 13.2 <10 18 <5 9

1 DUP-Factory Village Pond <1 <2 1 10 <5 442 29.5 <10 156 <5 32

13 DUP-Mountain Lake 2 5 <1 <10 <5 568 39.8 <10 85 <5 14

25 DUP-Tel Electric Pond 1 <2 1 <10 <5 398 26.3 <10 257 <5 37
Sediment Thickness, Chemical Quality, and Estimated Toxicity 19

Concentrations of Organic Compounds

High concentrations of organic compounds in bottom 

sediment are generally the result of human activity, although 

some PAHs have natural sources (Van Metre and others, 

2004). Of the 108 organic compounds tested in this study, 64 

were measured in concentrations greater than the laboratory 

reporting level (table 4, in back of report). In general, 

the highest concentrations of organic compounds were 

measured at the Ballardvale Dam (site 5) on the Shawsheen 

River in Andover (table 4, in back of report). Almost half 

of the individual compounds detected were found at their 

highest concentration at this site [number (n) of maximum 

concentrations = 26]. The site with the second largest number 

of maximum concentrations (n = 10) was the Deleano Pond 

Dam (site 28). This result was unexpected. Deleano Pond 

drains a relatively small drainage area (0.3 square mile) with 

no commercial, industrial, or transportation land use and is 

presently within the Harold Parker State Forest in northeastern 

Massachusetts. The Deleano Pond Dam was built in the 1930s 

and may have had an industrial history that is not evident by 

information readily available from a geographic information 

system (GIS). High concentrations of individual organic 

compounds were also measured at the Tel Electric Pond Dam 

(site 25) and the Felton Lake Dam on the Housatonic River in 

Washington (site 9) compared with measurements at the other 

sampling locations.

The maximum concentrations for the three major groups 

of organic compounds considered in this study (total PAHs, 

total PCBs, and total DDTs) are also of interest (fig. 7; table 4, 

in back of report). The maximum concentration of total PAHs 

was found at the Ballardvale Dam (site 5) where individual 

compounds were also present at elevated concentrations. The 

maximum concentration of total PCBs was found at the Mill 

Pond Dam (site 19; estimated value), and the maximum concentration of total DDTs was found at the Stony Brook Dam in 

Lincoln (site 24).

The major groups of compounds differed in their frequency of detection. Total PAHs were found most frequently, 

with detections at all 32 sites (100 percent of sites). Total 

PCBs were the least widespread, with detections at only 10 

of the sites (31 percent). Total DDTs were found at 29 of the 

sites (91 percent), a detection frequency between that of the 

other two groups. The relatively high rate of detection for total 

PAHs (69 percent of sites) suggests a potential likelihood of 

nonpoint sources of total PAHs in the contributing watersheds 

to the impoundments. The potential role of nonpoint sources 

of PAHs to impoundments is supported by recent research 

on sources of PAHs to the lakes and reservoirs of the United 

States (Van Metre and others, 2010). By contrast, the lower 

rate of detection for total PCBs (31 percent of sites) suggests 

that point sources may play an important role at sites where 

PCBs were detected during the present study. Recent research 

in Massachusetts (Breault and others, 2004) has provided sitespecific information on the role of PCB point sources in the 

contamination of impounded sediment.

Estimated Toxicity of Sediments

Although concentrations of priority pollutants may be 

used to help prioritize dam removal projects, contaminant concentrations alone do not indicate the potential risk posed by 

toxic contaminants. Potential toxicity of sediments to benthic 

organisms may be estimated by comparing observed contaminant concentrations in sediment to widely accepted criteria 

such as threshold effects concentrations (TECs) and probable 

effects concentrations (PECs; MacDonald and others, 2000). 

The TECs and PECs for each of the contaminants considered in this study (inorganic elements and organic compound 

groups) are shown on figures 6 and 7.

Among the inorganic elements, lead exceeded the PEC 

most frequently, with 7 of 32 impoundments (22 percent) 

having average lead concentrations above the PEC. Cadmium, chromium, and copper each exceeded the PEC at three 

impoundments (9 percent of sites), and arsenic exceeded the 

PEC at one impoundment. The remaining inorganic elements 

(nickel and zinc) did not exceed their PECs at any of the 

impoundments. Among the organic compound groups, total 

PAHs, total PCBs, and total DDTs exceeded the PEC at three, 

two, and zero sites, respectively.

The overall sediment toxicity at each of the impoundments was estimated by calculating the average PECQx

 for 

a sample (MacDonald and others (2000). The PECQx values 

(table 5) are used to assign an overall likelihood of toxicity (in 

percent) to each sediment sample (table 6). These likelihood 

values serve as indicators of the potential risk posed by the 

sediment to local and downstream receptors.

The likelihood of toxicity ranged from 8 to 70 percent 

among the sampling locations, and averaged 28 percent. A 

likelihood value of 28 percent means that 28 out of 100 toxicity tests are likely to show some level of toxicity for a given 

sample. Values greater than 60 percent were obtained for 3 of 

the 32 sites: Mill Pond Dam (site 19), Rice City Pond Dam 

(site 21), and Worcester Consolidated Station Dam (site 2). 

Cadmium was the largest single contributor to the estimated 

sediment toxicity at the two sites with the highest overall 

toxicity (Mill Pond Dam and Rice City Pond Dam; table 5). 

although total PCBs were also a large contributor to toxicity 

at the Mill Pond Dam. Copper was the largest contributor to 

toxicity at the Worcester Consolidated Station Dam, the site 

with the third highest overall toxicity. The Ballardville Dam 

(site 5) was the site where toxicity was most strongly dominated by a single contaminant—in this case, total PAHs, which 

contributed 70 percent of the overall toxicity. Chromium was a 

widespread contaminant; it contributed the largest single fraction of toxicity at 11 of the 32 sites, including not only sites 

with relatively low overall toxicity [Mill River Dam on the 

Mill River in Taunton (site 17) and Monument Pond #2 Dam 

on the Assonet River in Freetown (site 26)], but also sites with 

relatively high overall toxicity [Perryville Pond Dam (site 6) 

and Town Brook #1 Dam on the Town Brook in Plymouth 

(site 27)].
20 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts A 

Site number

Total Polycyclic Aromatic Hydrocarbons, in parts per billion

0 20,000 40,000 60,000 80,000 100,000

7

23322617

48

13

3

102415311811

62

12

1

2527292030142819212216

59

Figure 7. Concentrations for A, total polycyclic aromatic hydrocarbons, B, total polychlorinated biphenyls, and C, total dichlorodiphenyl-trichloroethylene (DDT) compounds 

in sediment samples from 32 impoundments in Massachusetts. Blue dashed line shows threshold effects concentration, and red dashed line shows the probable effects concentration (PEC) measured in parts per billion (ppb). The graph for DDT compounds does not show the PEC line because the value of the PEC (MacDonald and others, 2000) is more than 20 times greater than the highest DDT concentration from the 32 sampled sites. Sites are listed in table 1.
Sediment Thickness, Chemical Quality, and Estimated Toxicity 21

B

Total Polychlorinated Biphenyls, in parts per billion

0 500 1,000 1,500 2,000 2,500 3,000

8764321

29163012323128272624232018171514131110

5

22

9

192521

Site number

Figure 7. Concentrations for A, total polycyclic aromatic hydrocarbons, B, total polychlorinated biphenyls, and C, total dichlorodiphenyl-trichloroethylene (DDT) compounds 

in sediment samples from 32 impoundments in Massachusetts. Blue dashed line shows threshold effects concentration, and red dashed line shows the probable effects concentration (PEC) measured in parts per billion (ppb). The graph for DDT compounds does not show the PEC line because the value of the PEC (MacDonald and others, 2000) is more than 20 times greater than the highest DDT concentration from the 32 sampled sites. Sites are listed in table 1.—Continued
22 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts

0 20 40 60 80 100 120 140 160

321917

743

15111610261823

2

21

6

301314

8

29

9

2712

5

2220

1

25242831

PEC = 572 ppb

Total DDTs, in parts per billion

Site number

C

Figure 7. Concentrations for A, total polycyclic aromatic hydrocarbons, B, total polychlorinated biphenyls, and C, total dichlorodiphenyl-trichloroethylene (DDT) compounds 

in sediment samples from 32 impoundments in Massachusetts. Blue dashed line shows threshold effects concentration, and red dashed line shows the probable effects concentration (PEC) measured in parts per billion (ppb). The graph for DDT compounds does not show the PEC line because the value of the PEC (MacDonald and others, 2000) is more than 20 times greater than the highest DDT concentration from the 32 sampled sites. Sites are listed in table 1.—Continued
Sediment Thickness, Chemical Quality, and Estimated Toxicity 23

Table 5. Average probable effects concentration quotients for bottom-sediment cores collected from selected impoundments in Massachusetts in 2004 and 2005.[The probable effects concentration quotient (PECQ, dimensionless) is the ratio of the sample concentration to the probable effects concentration (PEC) for each contaminant at each site. The mean PECQ for a site (PECQx) is the overall average PECQ at a site for arsenic, cadmium, chromium, copper, lead, nickel, zinc, total polycyclic aromatic hydrocarbons (PAHs), total polychlorinated biphenyls (PCBs), and total dichlorodiphenyl-trichloroethane compounds (DDTs). Total PAHs comprise the sum of the concentrations of anthracene, 9-H fluorene, naphthalene, phenanthrene, benzo(a)anthracene, benzo(a)pyrene, chrysene, fluoranthene, and pyrene. Total DDTs comprise the sum of dichlorodiphenyl-trichloroethane (DDT) and dichlorodiphenyl-dichloroethylene (DDE) compounds; no., number]

Site 

no.

Dam name Arsenic PECQ Cad- mium PECQ Chro- mium PECQ Copper PECQ Lead PECQ Nickel PECQ Zinc PECQ Total PAHs PECQ Total PCBs PECQ Total DDT PECQ Mean for sample PECQx Maximum single con- tributor to to- tal estimated toxicity Percent of total toxicity from maxi- mum single contributor

1 Factory Village Pond 0.727 0.201 0.288 0.245 1.195 0.267 0.464 0.175 0.000 0.091 0.365 Lead 332 Horseshoe Pond 0.455 0.402 0.297 0.168 0.383 0.226 0.545 0.032 0.000 0.033 0.254 Zinc 213 Sheomet Lake 0.121 0.402 0.477 0.174 0.359 0.576 0.471 0.042 0.000 0.000 0.262 Nickel 224 North Webster Village Pond 0.182 0.100 0.820 0.241 0.367 0.206 0.113 0.010 0.000 0.000 0.204 Chromium 405 Ballardvale 0.212 0.100 0.387 0.053 0.203 0.267 0.325 4.053 0.163 0.065 0.583 Total PAHs 706 Perryville Pond 0.242 0.201 1.766 0.732 0.813 0.267 0.638 0.111 0.000 0.038 0.481 Chromium 377 Ipswich Mills 0.212 0.100 0.333 0.066 0.250 0.226 0.129 0.000 0.000 0.002 0.132 Chromium 258 Pentucket Pond Outlet 0.697 0.100 0.378 0.115 0.102 0.576 0.244 0.000 0.000 0.000 0.221 Arsenic 319 Felton Lake 0.121 0.402 0.198 0.075 0.227 0.123 0.229 2.507 0.399 0.000 0.428 Total PAHs 59

10 Watertown 0.303 0.803 0.541 0.285 1.109 0.350 0.429 0.051 0.000 0.014 0.389 Lead 29

11 Conway Electric 0.091 0.100 0.568 0.118 0.156 0.453 0.157 0.037 0.000 0.007 0.169 Chromium 34

12 D.F. Rile Grist Mill 0.091 0.100 0.315 0.075 0.133 0.329 0.149 0.147 0.044 0.056 0.144 Nickel 2313 Mountain Lake 0.242 0.100 0.450 0.139 0.641 0.309 0.199 0.000 0.000 0.031 0.211 Lead 3014 Carding Mill Pond 0.273 0.402 0.315 0.427 0.664 0.432 0.416 0.344 0.000 0.000 0.327 Lead 2015 Robert Meadow Upper Reservoir 0.091 0.100 0.523 0.142 0.289 0.453 0.253 0.047 0.000 0.014 0.191 Chromium 2716 Talbot Mills 0.394 0.100 0.694 0.340 0.492 0.329 0.312 0.186 0.074 0.000 0.292 Chromium 2417 Mill River 0.091 0.100 0.171 0.084 0.125 0.165 0.070 0.000 0.000 0.000 0.081 Chromium 2118 Windsor Reservoir 0.152 0.100 0.387 0.097 0.125 0.309 0.185 0.045 0.000 0.003 0.140 Chromium 2819 Mill Pond 0.333 3.815 0.541 0.505 1.602 0.288 0.444 0.257 3.698 0.000 1.148 Cadmium 3320 Mill Pond #1 1.121 0.100 0.279 0.327 0.727 0.226 0.261 0.387 0.000 0.000 0.343 Arsenic 3321 Rice City Pond 0.455 2.209 1.423 1.497 1.359 0.597 0.645 0.254 0.976 0.003 0.942 Cadmium 2322 Assabet River 0.364 0.201 0.739 1.040 0.859 0.453 0.606 0.231 0.266 0.065 0.482 Copper 2223 Upper Flints Pond 0.212 0.100 0.297 0.115 0.227 0.185 0.074 0.000 0.000 0.000 0.121 Chromium 2524 Stony Brook 0.424 0.100 0.378 0.168 0.523 0.370 0.288 0.015 0.000 0.157 0.242 Lead 2225 Tel Electric Pond 0.242 0.201 0.928 0.468 1.883 0.514 0.638 2.222 1.198 0.121 0.842 Total PAHs 2626 Monument Pond #2 0.091 0.100 0.225 0.072 0.117 0.165 0.076 0.004 0.000 0.000 0.085 Chromium 2627 Town Brook #1 0.576 0.100 1.396 0.389 1.281 0.350 0.312 0.730 0.000 0.000 0.513 Chromium 2728 Deleano Pond 0.121 0.100 0.216 0.152 0.141 0.185 0.046 0.304 0.000 0.093 0.136 Total PAHs 2229 Worcester Consolidated Station 0.636 1.807 0.928 2.523 1.219 0.741 0.708 0.653 0.148 0.000 0.936 Copper 2730 Cooks Canyon Lower Pond 0.152 0.100 0.279 0.158 0.602 0.206 0.193 0.350 0.059 0.019 0.212 Lead 2831 Unnamed, Stony Brook 0.485 0.100 0.378 0.179 0.352 0.370 0.227 0.000 0.000 0.129 0.222 Arsenic 2232 Unnamed, Winnetuxet 0.273 0.100 0.171 0.070 0.141 0.165 0.102 0.000 0.000 0.000 0.102 Arsenic 27
24 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts

Table 6. Likelihood of toxicity of bottom-sediment cores collected from selected 

impoundments in Massachusetts in 2004 and 2005.

[Likelihoood of toxicity calculated from equation 2 of this report (MacDonald and others, 2000). The 

average probable effects concentration quotient for a site (PECQx) is the average of the PECQs for arsenic, 

cadmium, chromium, copper, lead, nickel, and zinc, total polycyclic aromatic hydrocarbons (PAHs), 

total polychlorinated biphenyls (PCBs), and total dichlorodiphenyl-trichloroethylene (DDTs). For the 

purposes of this report, total DDTs comprise the sum of dichlorodiphenyl-trichloroethane and dichlorodiphenyl-dichloroethylene compounds. Total PAHs comprise the sum of the concentrations of anthracene, 

9H-fluorene, naphthalene, phenanthrene, benzo(a)anthracene, benzo(a)pyrene, chrysene, fluoranthene, and 

pyrene. no., number]

Site no. Dam name Mean 

PECQ

Estimated likelihood of toxicity 

of bottom-sediment cores, 

in percent

1 Factory Village Pond 0.365 32

2 Horseshoe Pond 0.254 23

3 Sheomet Lake 0.262 24

4 North Webster Village Pond 0.204 19

5 Ballardvale 0.583 46

6 Perryville Pond 0.481 39

7 Ipswich Mills 0.132 13

8 Pentucket Pond Outlet 0.221 21

9 Felton Lake 0.428 36

10 Watertown 0.389 33

11 Conway Electric 0.169 16

12 D.F. Rile Grist Mill 0.144 14

13 Mountain Lake 0.211 20

14 Carding Mill Pond 0.327 29

15 Robert Meadow Upper Reservoir 0.191 18

16 Talbot Mills 0.292 26

17 Mill River 0.081 8

18 Windsor Reservoir 0.140 14

19 Mill Pond 1.148 70

20 Mill Pond #1 0.343 30

21 Rice City Pond 0.942 63

22 Assabet River 0.482 39

23 Upper Flints Pond 0.121 12

24 Stony Brook 0.242 22

25 Tel Electric Pond 0.842 59

26 Monument Pond #2 0.085 8

27 Town Brook #1 0.513 41

28 Deleano Pond 0.136 13

29 Worcester Consolidated Station 0.936 62

30 Cooks Canyon Lower Pond 0.212 20

31 Unnamed, Stony Brook 0.222 21

32 Unnamed, Winnetuxet 0.102 10
Relations Among Contaminant Concentrations, Land Use, and Industrial History 25

This evaluation of potential toxicity was intended to 

distinguish contaminants or contaminant groups that are likely 

to be associated with adverse biological effects at specific 

sampling locations. Additionally, these data were calculated 

for homogenized core samples and may not represent potential toxicity at the present day sediment surface (top 4 inches) 

where many benthic organisms live and feed. Nevertheless, 

estimated toxicity values can be used to help evaluate the relative ecological risks present in the studied impoundments.

Relations Among Contaminant 

Concentrations, Land Use, and 

Industrial History

Present day land use has been shown to be an accurate 

predictor of shallow sediment chemistry in certain situations. For example, Chalmers and others (2007, figs. 2 and 

3) showed that the percentage of commercial, industrial, and 

transportation (CIT) land use in a drainage basin can be used 

to predict concentrations of both individual contaminant 

concentrations and average PECQs for lake and impoundment 

sediment accumulated since 1990 in New England. However, 

predicting potential risk to biota posed by toxic contaminants 

buried at deeper levels within sediment—representing pointand nonpoint-source contamination from activities in the 

drainage basin many decades in the past—has not been tested 

using this approach.

Correlation analysis was conducted to evaluate relations 

between basin characteristics and sediment contaminant 

concentrations, following the approach of Chalmers and others 

(2007). Concentrations of individual inorganic elements and 

organic compound groups (total PAHs, total PCBs, and total 

DDTs) were used as response variables. The explanatory 

variables tested were obtained from publicly available 

geospatial data layers, and included the drainage basin area 

upstream of each dam, the number of upstream dams, the 

percentage of impervious area, the percentage of commercial, 

industrial, and transportation land use in the basin in 1971 

and 2005, and the number of 21E1

 sites (Massachusetts Office 

of Geographic and Environmental Information, 2009). In 

addition, the number of factories operating in the 1830s in 

each drainage basin was obtained from a recent geospatial 

compilation of historical information (Hall and others, 2002). 

Information concerning land use in 1971 and the number of 

factories operating in each drainage basin in the 1830s was 

included in the analysis (table 7) to represent conditions prior 

to the effects of the U.S. Clean Water Act, enacted in 1972 

(U.S. Environmental Protection Agency, 2011).

1

Sites noted as 21E sites are oil and (or) hazardous material disposal sites 

that have been reported and classified under Massachusetts General Laws 

chapter 21E (General Court of the Commonwealth of Massachusetts, undated) 

and the Massachusetts Contingency Plan (310 CMR 40.0000; Massachusetts 

Department of Environmental Protection, undated).

Correlations between several of the response variables 

and particular explanatory, or landscape, variables were found 

to be statistically significant (p values less than 0.05) or highly 

significant (p less than 0.01; table 8). The landscape variable 

with the largest number of significant correlations with contaminant concentrations was the number of factories in each 

drainage area in the 1830s. Concentrations of five of the inorganic elements (chromium, copper, zinc, cadmium, lead) as 

well as total PAH concentrations were significantly correlated 

with this variable. Three other landscape variables (number of 

dams, commercial and industrial land use in 1971, and number 

of 21E sites) were found to be significantly correlated with 

inorganic metal concentrations, with each landscape variable 

showing significant correlations with a different subset of 

inorganic elements (table 8). One of the inorganic elements 

(arsenic) and two of the groups of organic compounds (total 

PCBs and total DDTs) showed no significant correlations with 

any of the landscape variables.

Other statistical approaches (univariate, multivariate, 

and logistic regression modeling with and without transformations of variables) were also tested to predict contaminant 

concentrations and toxicity potential. Numerous individual 

correlations between chemical concentrations and present day 

landscape variables were found to be statistically significant 

(as described above). However, none of the regression models 

described a sufficient amount of the overall variability to 

make the models useful for prediction of the depth-averaged, 

bulk sediment concentration at unsampled impoundments 

in Massachusetts. These findings suggest that human activities in Massachusetts drainage basins have varied to such an 

extent during the past 200 years that it may not be feasible to 

predict the depth-averaged quality of impounded sediment 

behind most unsampled impoundments, using models based 

largely on recent land use in the contributing drainage basin. 

If the objective of a particular investigation is to predict the 

chemical quality and potential toxicity of recently deposited 

(post-1990) sediment behind a dam in Massachusetts, existing 

models relating chemistry and potential toxicity to geospatial indicators of urbanization in New England (for example, 

Chalmers and others, 2007) may be sufficient for screening 

purposes. However, if the objective is to characterize average 

sediment quality and potential toxicity over the entire range 

of sediment depths, the results of this study suggest that sitespecific sampling will likely be required.

The data collected and interpreted for this study could 

provide a starting point for a statewide database of information 

concerning Massachusetts impoundments. Such a database 

could include data on impoundment water depths (bathymetry), impounded sediment thicknesses, sediment chemical 

quality, and potential toxicity of sediment to benthic organisms. This information could be used to help prioritize sites for 

dam removal, and to inform impounded sediment management 

decisions in the Commonwealth.
26 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts Table 7. Land use characteristics of selected impoundment drainage areas in Massachusetts. [Percent industrial, commercial, and transportation land use from the Massachusetts Office of Geographic and Environmental Information (2009). Sites designated as 21E sites are oil and (or) hazardous mate- rial disposal sites that have been reported and classified under Massachusetts General Laws chapter 21E (General Court of the Commonwealth of Massachusetts, undated) and the Massachusetts Contingency Plan (310 CMR 40.0000; Massachusetts Department of Environmental Protection, undated). Information on Massachusetts factories in 1830s was obtained from Hall and others (2002). no., number; mi2, square miles] Site no. Dam name Drainage area, in mi2 No. of dams in drainage area Impervious, in percent 1971 Land use 2005 Land use No. of 21E sites in drainage area No. of factories in 1830s Industrial, in percent Commercial, in percent Industrial, in percent Commercial, in percent Transportation, in percent

1 Factory Village Pond 5.2 4 4.8 0.23 0.33 0.23 0.36 0 2 52 Horseshoe Pond 57.1 57 9.6 0.01 0.15 0.21 0.50 1.3 5 113 Sheomet Lake 5.5 1 1.1 0 0 0 0 0 0 04 North Webster Village Pond 83.3 51 8.0 0.20 0.61 0.63 0.90 1.4 22 305 Ballardvale 65.7 8 20.1 3.0 1.7 5.9 2.5 3.6 50 46 Perryville Pond 93.3 65 8.6 0.35 0.76 0.76 1.1 1.3 40 377 Ipswich Mills 150 53 11.2 0.48 0.77 1.2 1.2 0.99 45 228 Pentucket Pond Outlet 7.5 1 8.2 0.12 0.29 0.13 0.46 0.09 2 09 Felton Lake 0.8 1 0.78 0 0 0 0 0 0 0

10 Watertown 273 86 16.4 1.3 1.4 2.4 1.8 1.5 146 69

11 Conway Electric 26.0 4 2.2 0 0.16 0.01 0.21 0 0 2

12 D.F. Rile Grist Mill 47.5 7 4.3 0.28 0.21 0.96 0.57 1.4 3 1013 Mountain Lake 2.2 1 37.9 0 5.1 1.3 5.3 5.6 1 014 Carding Mill Pond 3.9 3 12.1 0 2.1 0 4.7 0 0 015 Robert Meadow Upper Reservoir 8.8 1 1.3 0 0 0 0 0 0 116 Talbot Mills 368 135 12.9 0.98 1.6 2.2 2.3 1.4 112 4017 Mill River 41.1 18 9.5 0.17 0.19 1.2 0.50 1.4 5 818 Windsor Reservoir 14.8 1 1.6 0 0.04 0 0.04 0.09 0 119 Mill Pond 58.8 38 6.3 0.59 0.20 1.2 0.39 0.95 11 1820 Mill Pond #1 8.4 5 10.7 0.02 0.39 1.2 0.94 0.50 0 021 Rice City Pond 147 107 18.5 2.1 2.4 3.0 2.9 2.5 121 4722 Assabet River 30.0 25 13.8 0.24 1.0 1.6 2.5 1.4 8 623 Upper Flints Pond 7.9 1 9.6 0 0.06 0.91 0.41 2.3 1 024 Stony Brook 4.3 5 7.2 0 0.30 0 0.62 0 0 025 Tel Electric Pond 36.1 7 5.4 0.26 0.70 0.26 0.81 0.08 5 426 Monument Pond #2 20.7 6 6.7 0.02 0.08 0.06 0.14 0.88 0 027 Town Brook #1 8.5 6 10.7 0.05 0.39 1.2 0.94 0.49 0 128 Deleano Pond 0.3 1 8.5 0 0 0 0 0 0 029 Worcester Consolidated Station 83.1 72 20.4 3.0 2.9 3.9 3.3 3.3 98 2530 Cooks Canyon Lower Pond 1.6 1 4.5 0.67 0.01 0 0.01 0 0 031 Unnamed, Stony Brook 4.4 6 7.2 0 0.30 0 0.62 0 0 032 Unnamed, Winnetuxet 10.9 14 14.0 0.20 0.14 0.77 0.84 0.34 3 0
Relations Among Contaminant Concentrations, Land Use, and Industrial History 27

Table 8. Relations between sediment-core contaminant concentrations and land use in the drainage areas of selected impoundments 

in Massachusetts.

[CIT 2005 is the sum of commercial, industrial, and transportation land use for 2005; CI 1971 is the sum of commercial and industrial land use for 1971. Number of 21E sites is the number of oil and (or) hazardous material disposal sites that have been reported and classified under Massachusetts General Laws chapter 

21E and the Massachusetts Contingency Plan. r is the Pearson’s correlation coefficient. p value, a measure of statistical significance; p values less than 0.05 are 

considered significant and are in bold type. The number of factories in 1830s was obtained from Hall and others (2002); all other information was obtained from 

the Massachusetts Office of Geographic and Environmental Information (2009). DDT, dichlorodiphenyl-trichloroethane; PAH, polycyclic aromatic hydrocarbon; 

PCB, polychlorinated biphenyl]

Landscape characteristic

Chromium Nickel Copper Zinc Arsenic

r p value r p value r p value r p value r p value

Drainage area, in square miles 0.295 0.101 0.083 0.652 0.206 0.259 0.224 0.218 0.022 0.907

Number of dams 0.489 0.004 0.192 0.293 0.491 0.004 0.435 0.013 0.140 0.443

Impervious cover, in percent 0.168 0.357 0.120 0.515 0.339 0.057 0.168 0.357 0.207 0.256

CIT 2005, in percent 0.273 0.130 0.239 0.187 0.486 0.005 0.317 0.077 0.127 0.490

CI 1971, in percent 0.329 0.066 0.417 0.018 0.615 0.000 0.437 0.012 0.155 0.398

Number of 21E sites 0.417 0.018 0.317 0.077 0.523 0.002 0.416 0.018 0.130 0.480

Number of factories in the 1830s 0.500 0.004 0.159 0.386 0.398 0.024 0.394 0.026 0.047 0.800

Cadmium Lead Total PAH Total PCB Total DDT

r p value r p value r p value r p value r p value

Drainage area, in square miles 0.195 0.286 0.189 0.301 0.293 0.104 0.055 0.764 -0.212 0.245

Number of dams 0.398 0.024 0.316 0.078 0.316 0.078 0.144 0.431 -0.242 0.182

Impervious cover, in percent 0.122 0.506 0.203 0.266 0.049 0.790 -0.060 0.745 -0.059 0.750

CIT 2005, in percent 0.249 0.170 0.242 0.182 0.058 0.755 0.029 0.874 -0.130 0.478

CI 1971, in percent 0.346 0.052 0.360 0.043 0.121 0.511 0.065 0.724 -0.080 0.663

Number of 21E sites 0.377 0.034 0.337 0.059 0.340 0.057 0.056 0.760 -0.199 0.276

Number of factories in the 1830s 0.397 0.024 0.366 0.039 0.508 0.003 0.141 0.440 -0.209 0.251
28 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts

Summary

Contaminants in impounded sediment may be a source 

of contaminants to the overlying water column, to organisms 

that live on or in bottom sediment, and to wildlife and humans 

that come into contact with contaminated sediment. Such 

sediment may also be an ongoing source for resuspension, 

downstream transport, and dispersal of contaminants. The 

U.S. Geological Survey and the Massachusetts Department 

of Fish and Game, Division of Ecological Restoration 

collaborated to collect baseline information describing the 

thickness of impounded sediment and the concentrations of 

sediment-associated contaminants behind 32 dams throughout 

Massachusetts. Sediment-core samples were collected, and 

concentrations of 32 inorganic elements and 108 organic 

compounds were quantified.

Sediment thicknesses across the 32 impoundments 

ranged from 0 to more than 20 feet and averaged 3.7 feet. 

Bottom-sediment volumes—estimated by multiplying 

the average sediment thickness by impoundment surface 

area—ranged from about 55,000 cubic feet to 81 million 

cubic feet. Concentrations of contaminants toxic to benthic 

organisms, as well as the number detected above laboratory 

reporting levels, varied greatly among sampling locations. 

Of the impoundments sampled, the highest concentrations 

of inorganic elements and organic compounds generally 

were measured in samples collected from impoundments 

downstream of present or former urban and industrial areas, 

including the Blackstone and North Nashua Rivers (elements) 

and the Shawsheen River (organic compounds). The estimated 

probability of toxicity of bottom sediment ranged from about 

8 to 70 percent among the sampling locations and averaged 

slightly under 30 percent. Statistically significant correlations 

(p less than 0.05) were found between concentrations of some 

of the contaminants and upstream basin characteristics. In 

particular, significant correlations were found between the 

number of factories operating in each drainage basin in the 

1830s and the concentrations of several inorganic elements 

(cadmium, chromium, copper, lead, and zinc) as well as total 

PAH concentrations. However, predictive statistical models 

developed from the data were found to have a high degree 

of uncertainty. This result is consistent with the complex 

industrial history to which impoundments in Massachusetts 

have typically been subjected over their periods of deposition. 

This result also indicates that site-specific sampling may likely 

be required to characterize overall, depth-averaged sediment 

quality at unsampled impoundments in Massachusetts.

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Table 4 31

Table 4. Concentrations of organic compounds measured in bottom-sediment cores collected from selected impoundments in Massachusetts in 2004 and 2005.[Blue headings indicate members of total PAH group; yellow headings indicate members of total DDT group; gray heading indicates total PCB group. DDTs, dichlorodiphenyl-trichloroethane compounds; e, estimated; M, presence verified but not quantified; PAHs, polycyclic aromatic hydrocarbon compounds; PCBs, polychlorinated biphenyl compounds; ppb, parts per billion; V, value likely affected by contamination; --, not analyzed; <, less than value shown; %, percent]

Site 

no.

Dam name

1,2,4-Trichlorobenzene, 

in ppb

1,2-Dichlorobenzene, 

in ppb

1,2-Dimethylnaphthalene, 

in ppb

1,3-Dichlorobenzene, 

in ppb

1,4-Dichlorobenzene, 

in ppb

1,6-Dimethylnaphthalene, 

in ppb

1-Methyl-9Hfluorene, 

in ppb

1-Methylphenanthrene, 

in ppb

1-Methyl 

pyrene, 

in ppb

2,2’-Biquinoline, 

in ppb

1 Factory Village Pond <180 <180 <180 <180 <180 e43 <180 e110 e130 <1802 Horseshoe Pond <320 <320 <320 <320 <320 <320 <320 <320 <320 <3203 Sheomet Lake <63 <63 <63 <63 <63 e14 e20 98 e68 <634 North Webster Village Pond <85 <85 <85 <85 <85 e23 e26 <85 e30 <855 Ballardvale e34 e54 870 <70 120 1,700 1,400 3,900 2,800 <706 Perryville Pond <78 e8 e30 <78 <78 e42 e46 94 e64 <787 Ipswich Mills <310 <310 <310 <310 <310 <310 <310 <310 e44 <3108 Pentucket Pond Outlet <320 <320 <320 <320 <320 <320 <320 <320 <320 <3209 Felton Lake <62 <62 82 <62 <62 140 240 1,000 880 150

10 Watertown <62 <62 e21 <62 <62 e20 e30 e38 e34 <62

11 Conway Electric <120 <120 <120 <120 <120 <120 e42 e40 e51 <120

12 D.F. Rile Grist Mill <64 <64 e18 <64 <64 e27 e30 77 75 <6413 Mountain Lake <200 <200 <200 <200 <200 e62 <200 <200 <200 <20014 Carding Mill Pond <100 <100 e27 <100 <100 e57 e79 290 190 <10015 Robert Meadow Upper Reservoir <130 <130 e20 <130 <130 <130 <130 e54 <130 <13016 Talbot Mills <160 <160 <160 <160 <160 e34 e59 e110 e100 <16017 Mill River <58 <58 <58 <58 <58 <58 <58 <58 <58 <5818 Windsor Reservoir <64 <64 <64 <64 <64 e15 <64 e30 <64 <6419 Mill Pond <80 <80 87 <80 <80 360 100 200 170 <8020 Mill Pond #1 <290 <290 <290 <290 <290 e88 <290 e200 e180 <29021 Rice City Pond e27 <70 <70 <70 e16 120 120 170 240 <7022 Assabet River <140 <140 <140 <140 <140 e67 e68 e110 e120 <14023 Upper Flints Pond <100 <100 <100 <100 <100 <100 <100 <100 <100 <10024 Stony Brook <330 <330 <330 <330 <330 e47 e50 e38 e64 <33025 Tel Electric Pond e39 e61 e77 <85 e71 140 170 850 800 <8526 Monument Pond #2 <66 <66 <66 <66 <66 e11 <66 e18 e14 <6627 Town Brook #1 <120 <120 e55 <120 <120 130 160 600 290 <12028 Deleano Pond <650 <650 <650 <650 <650 e260 e250 e210 e280 e58029 Worcester Consolidated Station e13 e29 160 <65 <65 270 320 700 480 <6530 Cooks Canyon Lower Pond <75 <75 e43 <75 e10 e70 e69 200 140 <7531 Unnamed, Stony Brook <430 <430 <430 <430 <430 e53 <430 <430 <430 <43032 Unnamed, Winnetuxet <300 <300 <300 <300 <300 <300 <300 e43 <300 <300
32 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts Table 4. Concentrations of organic compounds measured in bottom-sediment cores collected from selected impoundments in Massachusetts in 2004 and 2005.—Continued [Blue headings indicate members of total PAH group; yellow headings indicate members of total DDT group; gray heading indicates total PCB group. DDTs, dichlorodiphenyl-trichloroethane compounds; e, esti- mated; M, presence verified but not quantified; PAHs, polycyclic aromatic hydrocarbon compounds; PCBs, polychlorinated biphenyl compounds; ppb, parts per billion; V, value likely affected by contamination; --, not analyzed; <, less than value shown; %, percent] Site no. Dam name 2,3,6-Trimeth- ylnaphthalene, in ppb 2,4,6-Trichlo- rophenol, in ppb 2,4,6-Trimeth- ylphenol, in ppb 2,4-Dichlo- rophenol, in ppb 2,4-Dini- trophenol, in ppb 2,4-Dini- trotoluene, in ppb 2,6-Dimethyl- naphthalene, in ppb 2,6-Dinitro- toluene, in ppb 2-Chloro- naphthalene, in ppb 2-Chloro- phenol, in ppb 

1 Factory Village Pond e39 -- -- -- -- <180 e100 <180 <180 <1802 Horseshoe Pond <320 -- -- -- -- <320 e180 <320 <320 <3203 Sheomet Lake <63 -- -- -- -- <63 e27 <63 <63 <634 North Webster Village Pond <85 -- -- -- -- <85 e50 <85 <85 <855 Ballardvale 1,000 -- -- -- -- <70 2,300 <70 <70 <706 Perryville Pond e40 -- -- -- -- <78 e54 <78 <78 <787 Ipswich Mills <310 -- -- -- -- <310 e94 <310 <310 <3108 Pentucket Pond Outlet <320 -- -- -- -- <320 e71 <320 <320 <3209 Felton Lake 180 -- <68 -- -- <68 260 <65 <62 <62

10 Watertown e25 -- -- -- -- <62 e24 <62 <62 <62

11 Conway Electric e46 -- -- -- -- <120 e61 690 <120 <120

12 D.F. Rile Grist Mill e28 -- -- -- -- <64 e53 <64 <64 <6413 Mountain Lake <200 -- -- -- -- <200 330 <200 <200 <20014 Carding Mill Pond <100 -- -- -- -- <100 110 <100 <100 <10015 Robert Meadow Upper Reservoir <130 -- -- -- -- <130 e56 <130 <130 <13016 Talbot Mills <160 -- -- -- -- <160 e70 <160 <160 <16017 Mill River <58 -- -- -- -- <58 e13 <58 <58 <5818 Windsor Reservoir <64 -- -- -- -- <64 e18 <64 <64 <6419 Mill Pond 160 -- -- -- <98 <80 440 <80 <80 <8020 Mill Pond #1 <290 -- -- -- -- <290 e290 <290 <290 <29021 Rice City Pond 120 -- -- -- -- <70 200 <70 <70 <7022 Assabet River e69 -- -- -- -- <140 e87 870 <140 <14023 Upper Flints Pond <100 -- -- -- -- <100 e44 <100 <100 <10024 Stony Brook <330 -- -- -- -- <330 e100 <330 <330 <33025 Tel Electric Pond 100 -- -- -- -- <85 200 <85 <85 <8526 Monument Pond #2 e0 -- -- -- -- <66 e16 <66 <66 <6627 Town Brook #1 e100 -- -- -- -- <120 230 <120 <120 <12028 Deleano Pond <650 -- -- -- -- <650 e520 3,800 <650 <65029 Worcester Consolidated Station 240 -- -- -- -- <65 450 <65 <65 <6530 Cooks Canyon Lower Pond 83 -- -- -- -- <75 100 440 <75 <7531 Unnamed, Stony Brook <430 -- -- -- -- <430 e160 <430 <430 <43032 Unnamed, Winnetuxet <300 -- -- -- -- <300 e58 <300 <300 <300
Table 4 33

Table 4. Concentrations of organic compounds measured in bottom-sediment cores collected from selected impoundments in Massachusetts in 2004 and 2005.—Continued[Blue headings indicate members of total PAH group; yellow headings indicate members of total DDT group; gray heading indicates total PCB group. DDTs, dichlorodiphenyl-trichloroethane compounds; e, estimated; M, presence verified but not quantified; PAHs, polycyclic aromatic hydrocarbon compounds; PCBs, polychlorinated biphenyl compounds; ppb, parts per billion; V, value likely affected by contamination; --, not analyzed; <, less than value shown; %, percent]

Site 

no.

Dam name

2-Ethylnaphthalene, 

in ppb

2-Methyl-4,6-

dinitrophenol, 

in ppb

2-Methylanthracene, 

in ppb

2-Nitrophenol, 

in ppb

3,5-Dimethylphenol, 

in ppb

3-Nitrophenol, 

in ppb

4-Bromophenyl 

phenyl ether, 

in ppb

4-Chloro3-methylphenol, 

in ppb

4-Chlorophenylphenyl ether, 

in ppb

1 Factory Village Pond e26 -- <180 -- <180 -- <180 <180 <1802 Horseshoe Pond <320 -- <320 -- <320 -- <320 <320 <3203 Sheomet Lake e17 -- e40 -- <63 -- <63 <63 <634 North Webster Village Pond e22 -- <85 -- <85 -- <85 <85 <855 Ballardvale 2,000 -- 3,200 -- <70 -- <70 <70 <706 Perryville Pond e31 -- e66 -- <78 -- <78 <78 <787 Ipswich Mills <310 -- <310 -- <310 -- <310 <310 <3108 Pentucket Pond Outlet <320 -- <320 -- <320 -- <320 <320 <3209 Felton Lake 110 -- 800 -- e39 -- <62 <62 <62

10 Watertown <62 -- e36 -- <62 -- <62 <62 <62

11 Conway Electric <120 -- e45 -- <120 -- <120 <120 <120

12 D.F. Rile Grist Mill e24 -- e47 -- <64 -- <64 <64 <6413 Mountain Lake <200 -- <200 -- <200 -- <200 <200 <20014 Carding Mill Pond e48 -- 160 -- <100 -- <100 <100 <10015 Robert Meadow Upper Reservoir <130 -- <130 -- <130 -- <130 <130 <13016 Talbot Mills <160 -- <160 -- <160 -- <160 <160 <16017 Mill River <58 -- <58 -- <58 -- <58 <58 <5818 Windsor Reservoir <64 -- e30 -- <64 -- <64 <64 <6419 Mill Pond 120 -- <80 -- <80 -- <80 <1,200 <8020 Mill Pond #1 <290 -- <290 -- <290 -- <290 <290 <29021 Rice City Pond 87 -- 120 -- <70 -- <70 <70 <7022 Assabet River <140 -- e99 -- <140 -- <140 <140 <14023 Upper Flints Pond <100 -- <100 -- <100 -- <100 <100 <10024 Stony Brook <330 -- <330 -- <330 -- <330 <330 <33025 Tel Electric Pond e80 -- 560 -- <85 -- <85 <85 <8526 Monument Pond #2 e9 -- <66 -- <66 -- <66 <66 <6627 Town Brook #1 e77 -- 360 -- <120 -- <120 <120 <12028 Deleano Pond <650 -- e220 -- <650 -- <650 <650 <65029 Worcester Consolidated Station 340 -- 410 -- <65 -- <65 <65 <6530 Cooks Canyon Lower Pond e31 -- 110 -- <75 -- <75 <75 <7531 Unnamed, Stony Brook <430 -- <430 -- <430 -- <430 <430 <43032 Unnamed, Winnetuxet <300 -- <300 -- <300 -- <300 <300 <300
34 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts Table 4. Concentrations of organic compounds measured in bottom-sediment cores collected from selected impoundments in Massachusetts in 2004 and 2005.—Continued [Blue headings indicate members of total PAH group; yellow headings indicate members of total DDT group; gray heading indicates total PCB group. DDTs, dichlorodiphenyl-trichloroethane compounds; e, estimated; M, presence verified but not quantified; PAHs, polycyclic aromatic hydrocarbon compounds; PCBs, polychlorinated biphenyl compounds; ppb, parts per billion; V, value likely affected by con- tamination; --, not analyzed; <, less than value shown; %, percent] Site no. Dam name 4H-Cyclopenta[def] phenanthrene, in ppb 9,10-Anthra- quinone, in ppb 9H-Fluorene, in ppb Acenaph- thene, in ppb Acenaph- thylene, in ppb Acridine, in ppb Aldrin, in ppb alpha- Endosulfan, in ppb alpha- HCH, in ppb

1 Factory Village Pond e140 240 e100 e31 e110 <180 1 <3 <32 Horseshoe Pond <320 e260 <320 <320 e78 <320 <6 <6 <63 Sheomet Lake e39 e62 e22 e10 e38 e26 <1 <1 <14 North Webster Village Pond e20 e59 e34 e26 e38 <85 <2 <2 <25 Ballardvale 4,900 <70 4,400 5,800 2,700 <70 2 <1

M

6 Perryville Pond 100 130 e71 e34 100 <78 <1 <1 <17 Ipswich Mills e52 <310 <310 <310 <310 <310 <6 <6 <68 Pentucket Pond Outlet <320 <320 <320 <320 <320 <320 <6 <6 <69 Felton Lake 1,700 1,400 940 510 1,400 400 <1 <1 <1

10 Watertown e58 72 e51 e23 e54 <62 <1 <1 <1

11 Conway Electric e53 e63 e51 e33 e65 <120 <2 <2 <2

12 D.F. Rile Grist Mill 100 150 74 e28 93 e54 <1 <1 <113 Mountain Lake e34 e130 <200 e22 e60 <200 <4 <4 <414 Carding Mill Pond 270 450 170 e71 580 <100 <2 <2 <215 Robert Meadow Upper Reservoir e47 e120 <130 e18 e61 <130 <3 <3 <316 Talbot Mills e160 250 e90 e34 e140 <160 <3 <3 <317 Mill River e11 e38 <58 e5 e15 <58 <1 <1 <118 Windsor Reservoir e43 e62 e40 e13 e33 <64 <1 <1 <119 Mill Pond 200 <80 180 96 180 <80 <1 <1 <120 Mill Pond #1 e280 500 e190 e88 e150 <290 <6 <6 <621 Rice City Pond 160 110 140 89 390 <70 <1 <1 <122 Assabet River 160 190 e96 e63 190 <140 <2 <2 <223 Upper Flints Pond e12 e58 e25 <100 e26 <100 <2 <2 <224 Stony Brook e45 e130 e45 <330 e62 <330 <6 <6 <625 Tel Electric Pond 1,200 1,700 720 460 1,800 160 <1 <1 <126 Monument Pond #2 e8 e46 <66 e5 <66 <66 <1 <1 <127 Town Brook #1 640 670 520 460 370 170 <2 <2 <228 Deleano Pond e340 e500 e260 e160 e310 e160 <13 <13 <1329 Worcester Consolidated Station 590 <65 670 620 620 <65 <1 <4 <130 Cooks Canyon Lower Pond 200 220 120 e56 340 <75 <1 <1 <131 Unnamed, Stony Brook <430 <430 <430 <430 e50 <430 <8 <8 <832 Unnamed, Winnetuxet <300 <300 <300 <300 <300 <300 <6 <6 <6
Table 4 35

Table 4. Concentrations of organic compounds measured in bottom-sediment cores collected from selected impoundments in Massachusetts in 2004 and 2005.—Continued[Blue headings indicate members of total PAH group; yellow headings indicate members of total DDT group; gray heading indicates total PCB group. DDTs, dichlorodiphenyl-trichloroethane compounds; e, estimated; M, presence verified but not quantified; PAHs, polycyclic aromatic hydrocarbon compounds; PCBs, polychlorinated biphenyl compounds; ppb, parts per billion; V, value likely affected by contamination; --, not analyzed; <, less than value shown; %, percent]

Site 

no.

Dam name

Anthracene, 

in ppb

Azobenzene, 

in ppb

Benzo[a]

anthracene, 

in ppb

Benzo[a]

pyrene, 

in ppb

Benzo[b]fluoranthene, 

in ppb

Benzo[c]

cinnoline, 

in ppb

Benzo[ghi]- 

perylene, 

in ppb

Benzo[k]fluoranthene, 

in ppb

Benzyl n-butyl 

phthalate, 

in ppb

betaHCH, 

in ppb

1 Factory Village Pond 220 <180 500 490 780 <180 e160 270 <190 <32 Horseshoe Pond e100 <320 e170 <320 330 <320 e160 e130 <380 <63 Sheomet Lake e47 <63 150 150 e160 <63 e74 e68 <63 <14 North Webster Village Pond e40 <85 e58 e74 88 <85 <85 e36 <100 <25 Ballardvale 9,600 <70 9,000 8,000 4,700 <70 1,200 5,200 <70 <16 Perryville Pond 120 <78 300 e300 540 <78 e210 200 <78 <17 Ipswich Mills e60 <310 <310 <310 <310 <310 <310 <310 <310 <68 Pentucket Pond Outlet <320 <320 e98 <320 <320 <320 <320 <320 <380 <69 Felton Lake 2,400 <1,000 6,200 6,300 7,400 <62 e4,400 3,300 e260 <1

10 Watertown e61 <62 140 e150 250 <62 e140 120 <62 <1

11 Conway Electric e70 <120 130 e120 e100 <120 e95 e110 V <2

12 D.F. Rile Grist Mill 120 <64 300 370 590 <64 e200 230 <100 <113 Mountain Lake e62 <200 e91 e130 e160 <200 <200 e63 <290 <414 Carding Mill Pond 390 <100 760 1,100 940 <100 740 890 <170 <215 Robert Meadow Upper Reservoir e66 <130 e120 140 e220 <130 <130 e96 <150 <316 Talbot Mills 180 <160 460 480 e740 <160 e230 290 <160 <317 Mill River e17 <58 e25 e35 e45 <58 e34 e23 <58 <118 Windsor Reservoir e61 <64 120 120 150 <64 e85 78 <75 <119 Mill Pond 310 <200 510 420 410 <80 260 320 <80 <120 Mill Pond #1 e260 <290 920 1,100 1,800 <290 e620 750 <550 <621 Rice City Pond 370 <70 560 630 e440 <70 510 e520 V <122 Assabet River 260 <140 590 480 500 <140 340 500 V <223 Upper Flints Pond e26 <100 e35 e56 e49 <100 <100 e19 <140 <224 Stony Brook e74 <330 e130 e160 e200 <330 e120 e140 420 <625 Tel Electric Pond 2,300 <85 4,900 5,600 5,200 <85 3,700 4,800 V <126 Monument Pond #2 e14 <66 e19 e22 e27 <66 e22 e12 <110 <127 Town Brook #1 840 <120 1,700 1,600 1,400 <120 1,000 1,400 <210 <228 Deleano Pond e300 <650 720 790 880 <650 e680 800 V <1329 Worcester Consolidated Station 860 <65 1,500 1,400 1,100 <65 890 1,000 e160 <130 Cooks Canyon Lower Pond 360 <75 890 1,200 1,000 <75 790 920 V <131 Unnamed, Stony Brook e67 <430 e100 e140 e99 <430 e140 e80 e390 <832 Unnamed, Winnetuxet e36 <300 <300 <300 <300 <300 <300 <300 e290 <6
36 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts Table 4. Concentrations of organic compounds measured in bottom-sediment cores collected from selected impoundments in Massachusetts in 2004 and 2005.—Continued [Blue headings indicate members of total PAH group; yellow headings indicate members of total DDT group; gray heading indicates total PCB group. DDTs, dichlorodiphenyl-trichloroethane compounds; e, estimated; M, presence verified but not quantified; PAHs, polycyclic aromatic hydrocarbon compounds; PCBs, polychlorinated biphenyl compounds; ppb, parts per billion; V, value likely affected by con- tamination; --, not analyzed; <, less than value shown; %, percent] Site no. Dam name Bis(2-chlo- roethoxy) methane, in ppb Bis(2-chlo- roethyl) ether, in ppb Bis(2-chlo- roisopropyl) ether, in ppb Bis(2- ethylhexyl) phthalate, in ppb C8-Alkyl- phenol, in ppb Carbazole, in ppb Chloroneb, in ppb Chrysene, in ppb cis-Chlor- dane, in ppb cis-Non- achlor, in ppb

1 Factory Village Pond <180 <180 -- <190 <180 e75 8 560 <3 <32 Horseshoe Pond <320 <320 -- e1,000 e95 <320 <30 e200 <6 <63 Sheomet Lake <63 <63 -- e120 <63 <63 <5 170 <1 <14 North Webster Village Pond <85 <85 -- <85 <85 e38 <8 e61 <2 <25 Ballardvale <70 <70 -- 2,200 <70 140 <5 8,800

M <1

6 Perryville Pond <78 <78 -- <100 <78 e45 <5 390

M

M

7 Ipswich Mills <310 <310 -- <310 e88 <310 <30 <310 <6 <68 Pentucket Pond Outlet <320 <320 -- <320 <320 <320 <30 e95 <6 <69 Felton Lake <62 <62 -- 12,000 e49 560 <5 7,100 <1 e1

10 Watertown <62 <62 -- <62 <62 e28 <5 150 <1 <1

11 Conway Electric <120 <120 --

V <120 e23 <10 130 <2 <2

12 D.F. Rile Grist Mill <64 <64 -- 740 <64 e51 <5 470 10 213 Mountain Lake <200 <200 -- <230 <200 <200 <20 e96 <4 <414 Carding Mill Pond <100 <100 -- e220 <100 160 <10 1,000 <2 <215 Robert Meadow Upper Reservoir <130 <130 -- <130 e53 <130 <15 150 <3 <316 Talbot Mills <160 <160 -- <240 e69 <160 <15 570 <3 <317 Mill River <58 <58 -- <58 <58 <58 <5 e27 <1 <118 Windsor Reservoir <64 <64 -- <.0 e23 e25 <5 120 <1 <119 Mill Pond <80 <80 -- 82 <80 e46 <5 680 <1 <220 Mill Pond #1 <290 <290 -- <480 e110 e170 <30 1,300 <6 <621 Rice City Pond <70 <70 -- 1,600 <70 e28 <5 830 4 M22 Assabet River <140 <140 -- 1,300 <140 e69 <10 720 3 e123 Upper Flints Pond <100 <100 -- <100 <100 <100 <10 e22 <2 <224 Stony Brook <330 <330 -- e220 <330 <330 <30 e180 <6 <1225 Tel Electric Pond <85 <85 -- 1,400 <85 760 <5 6,400 4 M26 Monument Pond #2 <66 <66 -- <66 <66 <66 <5 e18 <1 <127 Town Brook #1 <120 <120 -- <170 e68 450 <12 1,800 <2 <228 Deleano Pond <650 <650 --

V <650 e160 <65 1,000 15 e10

29 Worcester Consolidated Station <65 <65 -- 1,000 <65 140 <5 1,600 e2 <130 Cooks Canyon Lower Pond <75 <75 --

V <75 95 <5 1,100

M <1

31 Unnamed, Stony Brook <430 <430 -- 1,400 <430 <430 <40 e130 <8 <1632 Unnamed, Winnetuxet <300 <300 -- e88 <300 <300 <30 <300 <6 <12
Table 4 37

Table 4. Concentrations of organic compounds measured in bottom-sediment cores collected from selected impoundments in Massachusetts in 2004 and 2005.—Continued[Blue headings indicate members of total PAH group; yellow headings indicate members of total DDT group; gray heading indicates total PCB group. DDTs, dichlorodiphenyl-trichloroethane compounds; e, estimated; M, presence verified but not quantified; PAHs, polycyclic aromatic hydrocarbon compounds; PCBs, polychlorinated biphenyl compounds; ppb, parts per billion; V, value likely affected by contamination; --, not analyzed; <, less than value shown; %, percent]

Site 

no.

Dam name

cis-Permethrin, 

in ppb

DCPA, 

in ppb

Dibenzo[a,h]

anthracene, 

in ppb

Dibenzothiophene, 

in ppb

Dieldrin, 

in ppb

Diethyl 

phthalate, 

in ppb

Dimethyl 

phthalate, 

in ppb

Di-n-butyl 

phthalate, 

in ppb

Di-n-octyl 

phthalate, 

in ppb

Endrin, 

in ppb

1 Factory Village Pond <15 <15 <180 <180 2 <180 <180 <180 <180 <62 Horseshoe Pond <30 <30 <320 <320 <6 e82 <320 <320 <320 <123 Sheomet Lake <5 <5 e40 <63 <1 <63 <63 <63 <63 <24 North Webster Village Pond <8 <8 <85 <85 <2 <85 <85 <85 <85 <35 Ballardvale <5 <5 770 1,700 20 V <70 <70 <70 <26 Perryville Pond <5 <5 <78 e54 <1 <78 <78 <78 <78 <27 Ipswich Mills <30 <30 <310 <310 <6 <310 <310 <310 <310 <128 Pentucket Pond Outlet <30 <30 <320 <320 <6 <320 <320 <320 <320 <129 Felton Lake <5 <5 e260 560 <1 <62 <62 e130 e200 <2

10 Watertown <5 <5 <62 e32 <1 <62 <62 <62 <62 <2

11 Conway Electric <10 <10 e36 e39 <2 V <120 V <120 <4

12 D.F. Rile Grist Mill <5 <5 e48 e42 e2 <64 <64 <64 <64 <213 Mountain Lake <20 <20 <200 <200 <4 <200 <200 <200 <200 <814 Carding Mill Pond <10 <10 350 110 <2 <100 <100 <100 <100 <415 Robert Meadow Upper Reservoir <15 <15 e79 <130 <3 <130 <130 <130 <130 <616 Talbot Mills <15 <15 <160 <160 e3 <160 <160 <160 <160 <617 Mill River <5 <5 <58 <58 <1 <58 <58 <58 <58 <218 Windsor Reservoir <5 <5 <64 e24 <1 <64 <64 <64 <64 <219 Mill Pond <5 <5 <140 100 <1 <80 <80 <80 <80 <220 Mill Pond #1 <30 <30 e100 e120 <6 <290 <290 <290 <290 <1221 Rice City Pond <5 <5 180 100 65 V <70 <70 <70 M22 Assabet River <10 <10 e120 e73 <2 V <140 V <140 <423 Upper Flints Pond <10 <10 <100 <100 <2 <100 <100 <100 <100 <424 Stony Brook <30 <30 <330 <330 <6 <330 <330 e170 <330 <1225 Tel Electric Pond <5 <5 1,200 370 <1 V <85 V <85 <226 Monument Pond #2 <5 <5 <66 <66 <1 <66 <66 <66 <66 <227 Town Brook #1 <12 <12 460 280 <2 <120 <120 <120 <120 <528 Deleano Pond <65 <65 e250 e220 <13 V <650 V <650 <2629 Worcester Consolidated Station <5 <5 330 290 <1 <65 <65 <65 <65 <230 Cooks Canyon Lower Pond <5 <5 380 84 <1 V <75 V <75 <231 Unnamed, Stony Brook <40 <40 <430 <430 <8 <430 <430 e210 <430 <1632 Unnamed, Winnetuxet <30 <30 <300 380 <6 <300 <300 e140 <300 <12
38 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts Table 4. Concentrations of organic compounds measured in bottom-sediment cores collected from selected impoundments in Massachusetts in 2004 and 2005.—Continued [Blue headings indicate members of total PAH group; yellow headings indicate members of total DDT group; gray heading indicates total PCB group. DDTs, dichlorodiphenyl-trichloroethane compounds; e, estimated; M, presence verified but not quantified; PAHs, polycyclic aromatic hydrocarbon compounds; PCBs, polychlorinated biphenyl compounds; ppb, parts per billion; V, value likely affected by con- tamination; --, not analyzed; <, less than value shown; %, percent] Site no. Dam name Fluoran- thene, in ppb Heptachlor epoxide, in ppb Hepta- chlor, in ppb Hexachloro- benzene, in ppb Hexachloro- butadiene, in ppb Hexachlorocy- clopentadiene, in ppb Hexachlo- roethane, in ppb Indeno[1,2,3- cd]pyrene, in ppb Isodrin, in ppb Isopho- rone, in ppb

1 Factory Village Pond 900 <3 <3 <3 -- -- -- e180 <3 <1802 Horseshoe Pond 390 <6 <6 <6 -- -- -- <320 <6 <3203 Sheomet Lake 170 <1 <1 <1 -- -- -- e75 <1 <634 North Webster Village Pond 120 <2 <2 <2 -- -- -- e78 <1 <855 Ballardvale 14,000 <1 <1 2 -- -- -- 3,600 <1 <706 Perryville Pond 730 <1 <1 <1 -- -- -- e210 <1 <787 Ipswich Mills e72 <6 <6 3 -- -- -- <310 <6 <3108 Pentucket Pond Outlet e160 <6 <6 e12 -- -- -- <320 <6 <3209 Felton Lake 14,000 <1 <1 <1 -- -- -- 4,200 <1 <62

10 Watertown 360 <1 <1 <1 -- -- -- e130 <1 <62

11 Conway Electric 230 <2 <2 <2 -- -- -- e75 <2 <120

12 D.F. Rile Grist Mill 830 <1 <1 <1 -- -- -- 210 <1 <6413 Mountain Lake e190 <4 <4 <4 -- -- -- e160 <1 <20014 Carding Mill Pond 1,700 <2 <2 <2 -- -- -- 770 <1 <10015 Robert Meadow Upper Reservoir 320 <3 <3 <3 -- -- -- e120 <3 <13016 Talbot Mills 1,100 <3 <3 <3 -- -- -- e250 <3 <16017 Mill River e55 <1 <1 <1 -- -- -- e39 <1 <5818 Windsor Reservoir 260 <1 <1 <1 -- -- -- 86 <1 <6419 Mill Pond 1,200 <1 <1 <1 -- -- -- 310 <1 <8020 Mill Pond #1 2,500 <6 <6 <6 -- -- -- e650 <6 <29021 Rice City Pond 980 <1 <1 <1 -- -- -- 640 <1 <7022 Assabet River 1,400 <2 <2 <2 -- -- -- 400 <2 <14023 Upper Flints Pond e69 <2 <2 <2 -- -- -- <100 <1 <10024 Stony Brook 350 <6 <6 <6 -- -- -- e140 <6 <33025 Tel Electric Pond 12,000 <1 <1

M -- -- -- 4,100 <1 <85

26 Monument Pond #2 e37 <1 <1 <1 -- -- -- e22 <1 <6627 Town Brook #1 3,800 <2 <2 <2 -- -- -- 1,100 <1 <12028 Deleano Pond 2,000 <13 <13 <13 -- -- -- e560 <13 <65029 Worcester Consolidated Station 2,400 <1 <1 <1 -- -- -- 890 <1 <6530 Cooks Canyon Lower Pond 1,600 <1 <1 <1 -- -- -- 590 <1 <7531 Unnamed, Stony Brook e280 <8 <8 <8 -- -- -- <430 <8 <43032 Unnamed, Winnetuxet e120 <6 <6 <6 -- -- -- <300 <6 <300
Table 4 39

Table 4. Concentrations of organic compounds measured in bottom-sediment cores collected from selected impoundments in Massachusetts in 2004 and 2005.—Continued[Blue headings indicate members of total PAH group; yellow headings indicate members of total DDT group; gray heading indicates total PCB group. DDTs, dichlorodiphenyl-trichloroethane compounds; e, estimated; M, presence verified but not quantified; PAHs, polycyclic aromatic hydrocarbon compounds; PCBs, polychlorinated biphenyl compounds; ppb, parts per billion; V, value likely affected by contamination; --, not analyzed; <, less than value shown; %, percent]

Site 

no.

Dam name Isoquinoline, in ppb Lindane, in ppb Mirex, in ppb Naphthalene, in ppb Nitrobenzene, in ppb N-Nitrosodi-n- propylamine, in ppb N-Nitrosodi- phenylamine, in ppb o,p’-DDD, in ppb o,p’-DDE, in ppb

1 Factory Village Pond <180 <3 <3 e60 <180 <180 <180 8 <32 Horseshoe Pond <320 <6 <6 e22 <320 <320 <320 2 <63 Sheomet Lake <63 <1 <1 <63 <63 <63 <63 <1 <14 North Webster Village Pond <85 <2 <2 e20 <85 <85 <85 <2 <25 Ballardvale 76 <1 <1 2,600 <70 <70 <70 10 26 Perryville Pond <78 <1 <1 e64 <78 <78 <78 3 37 Ipswich Mills <310 <6 <6 <310 <310 <310 <310 <6 <68 Pentucket Pond Outlet <320 <6 <6 <320 <320 <320 <320 <6 <69 Felton Lake <62 <1 <1 410 <62 <62 <68 <1 <1

10 Watertown <62 <1 <1 e14 <62 <62 <62 1 <1

11 Conway Electric e47 <2 <2 e19 <120 <120 <120 e1 <2

12 D.F. Rile Grist Mill <64 <1 <1 e57 <64 <64 <64 6 <113 Mountain Lake <200 <4 <4 <200 <200 <200 <200 <4 <414 Carding Mill Pond <100 <2 <2 120 <100 <100 <100 <2 <215 Robert Meadow Upper Reservoir <130 <3 <3 <130 <130 <130 <130 <3 <316 Talbot Mills <160 <3 <3 e53 <160 <160 <160 <3 <317 Mill River <58 <1 <1 <58 <58 <58 <58 <1 <118 Windsor Reservoir <64 <1 <1 <64 <64 <64 <64 <1 <119 Mill Pond <80 <1 <1 260 <80 <80 <80 <1 <120 Mill Pond #1 <290 <6 <6 e64 <290 <290 <290 <6 <621 Rice City Pond <70 <1 <1 190 <70 <70 <70 2 <122 Assabet River <140 <2 <2 e56 <140 <140 <140 11 423 Upper Flints Pond <100 <2 <2 <100 <100 <100 <100 <2 <224 Stony Brook <330 <6 <6 <330 <330 <330 <330 28 <625 Tel Electric Pond <85 <1 <1 340 <85 <85 <85 26 <126 Monument Pond #2 e35 <1 <1 88 <66 <66 <66 <1 <127 Town Brook #1 e79 <2 <2 280 <120 <120 <120 <2 <228 Deleano Pond <650 13 <13 e100 <650 <650 <650 15 <1329 Worcester Consolidated Station <65 <1 <1 950 <65 <65 <65 e5 <130 Cooks Canyon Lower Pond <75 <1 <1 e46 <75 <75 <75 7 M31 Unnamed, Stony Brook <430 <8 <8 <430 <430 <430 <430 26 <832 Unnamed, Winnetuxet <300 <6 <6 <300 <300 <300 <300 <6 <6
40 Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts Table 4. Concentrations of organic compounds measured in bottom-sediment cores collected from selected impoundments in Massachusetts in 2004 and 2005.—Continued [Blue headings indicate members of total PAH group; yellow headings indicate members of total DDT group; gray heading indicates total PCB group. DDTs, dichlorodiphenyl-trichloroethane compounds; e, estimated; M, presence verified but not quantified; PAHs, polycyclic aromatic hydrocarbon compounds; PCBs, polychlorinated biphenyl compounds; ppb, parts per billion; V, value likely affected by con- tamination; --, not analyzed; <, less than value shown; %, percent] Site no. Dam name o,p’-DDT, in ppb o,p’-Metho- xychlor, in ppb Oxychlordane, in ppb p,p’-DDD, in ppb p,p’-DDE, in ppb p,p’-DDT, in ppb p,p’-Metho- xychlor, in ppb Total PCBs, in ppb p-Cresol, in ppb Pentachloro- anisole, in ppb

1 Factory Village Pond <6 <15 <3 42 e24 2 <15 <150 e750 <32 Horseshoe Pond <12 <30 <6 10 7 <12 <30 <300 e2,300 <63 Sheomet Lake <2 <5 <1 <1 e1 <2 <5 <50 <63 <14 North Webster Village Pond <3 <8 <2 <2 e1 <3 <8 <80 160 <25 Ballardvale e1 <5 <1 e19 25

M <5 110 <70 <1

6 Perryville Pond <2 <5 <1 11 5 e1 <5 <50 e52 <17 Ipswich Mills <12 <30 <6 <6 1 <12 <30 <300 e88 <68 Pentucket Pond Outlet <12 <30 <6 e21 e9 <12 <30 <300 e190 <69 Felton Lake <2 <5 <1 e27 e12 <2 <5 e270 e160 <1

10 Watertown <2 <5 <1 5 2 <2 <5 <50 e29 <1

11 Conway Electric <4 <10 <2 e5 4 <4 <10 <100 <120 <2

12 D.F. Rile Grist Mill <2 <5 <1 26 e5 e2 <5 e30 e31 <113 Mountain Lake <8 <20 <4 e9 18 <8 <20 <200 <200 <414 Carding Mill Pond <4 <10 <2 e13 e6 e4 <10 <100 220 <215 Robert Meadow Upper Reservoir <6 <15 <3 8 e3 <6 <15 <150 <130 <316 Talbot Mills <6 <15 <3 e4 e4 <6 <15 e50 e130 <317 Mill River <2 <5 <1 <1 <1 <2 <5 <50 <58 <118 Windsor Reservoir <2 <5 <1 2 M <2 <5 <50 e28 <119 Mill Pond <2 <5 <1 <1 <1 <2 <5 e2,500 <80 <120 Mill Pond #1 <12 <30 <6 e38 e31 <12 <30 <300 e170 <621 Rice City Pond

M <5 <1 e6 e11 e2 <5 e660 e43

M

22 Assabet River <4 <10 <2 e37 22 <4 <10 180 <140 <223 Upper Flints Pond <4 <10 <2 e1

M <4 <10 <100 e91 <1

24 Stony Brook <12 <30 <6 e28 62 <12 <30 <300 <330 <625 Tel Electric Pond <2 <5 <1 e92 26 17 <5 810 e75 <126 Monument Pond #2 <2 <5 <1 <1 <1 <2 <5 <50 120 <127 Town Brook #1 <5 <12 <2 e26 e18 <5 <12 <120 300 <228 Deleano Pond <26 <65 <13 e46 38 <26 <65 <650 <650 <1329 Worcester Consolidated Station <2 <5 <1 e14 e11 <2 <5 100 330 <130 Cooks Canyon Lower Pond <2 <5 <1 e16 4 <4 <5 e40 <75 <131 Unnamed, Stony Brook <16 <40 <8 e12 48 <16 <40 <400 <430 <832 Unnamed, Winnetuxet <12 <30 <6 <6 <6 <12 <30 <300 <300 <6
Table 4 41

Table 4. Concentrations of organic compounds measured in bottom-sediment cores collected from selected impoundments in Massachusetts in 2004 and 2005.—Continued[Blue headings indicate members of total PAH group; yellow headings indicate members of total DDT group; gray heading indicates total PCB group. DDTs, dichlorodiphenyl-trichloroethane compounds; e, estimated; M, presence verified but not quantified; PAHs, polycyclic aromatic hydrocarbon compounds; PCBs, polychlorinated biphenyl compounds; ppb, parts per billion; V, value likely affected by contamination; --, not analyzed; <, less than value shown; %, percent]

Site 

no.

Dam name

Pentachloronitrobenzene, 

in ppb

Pentachlorophenol, 

in ppb

Phenanthrene, 

in ppb

Phenanthridine, 

in ppb

Phenol, 

in ppb

Pyrene, 

in ppb

Quinoline, 

in ppb

Toxaphene, 

in ppb

transChlordane, 

in ppb

transNonachlor, 

in ppb

transPermethr,

in ppb

1 Factory Village Pond <180 -- 500 <180 <180 810 <180 <600 <3 <3 <152 Horseshoe Pond <320 -- e250 <320 <320 330 <320 <1,200 <6 <6 <303 Sheomet Lake <63 -- 83 <63 <63 230 <63 <200 <1 <1 <54 North Webster Village Pond <85 -- e81 <85 e38 100 <85 <300 <2 <2 <85 Ballardvale <70 -- 17,000 <70 <70 19,000 <70 <200 1 M <56 Perryville Pond <78 -- 420 e36 e42 580 <78 <200 M <1 <57 Ipswich Mills <310 e240 e33 <310 <310 e60 <310 <1,200 <6 <6 <308 Pentucket Pond Outlet <320 -- e85 <320 e120 e140 <320 <1,200 <6 <6 <309 Felton Lake <62 -- 7,800 170 80 12,000 e38 <200 <1 <1 <5

10 Watertown <62 -- 230 e27 100 280 <62 <200 <1 <1 <5

11 Conway Electric <120 -- 160 <120 e93 190 <120 <400 <2 <2 <10

12 D.F. Rile Grist Mill <64 -- 440 <64 e34 750 <64 <200 10 6 <513 Mountain Lake <200 -- e100 <200 e68 e160 <200 <800 e2 <4 <2014 Carding Mill Pond <100 -- 1,000 <100 e67 1,600 <100 <400 <2 <2 <1015 Robert Meadow Upper Reservoir <130 -- 200 <130 e46 270 <130 <600 <3 <3 <1516 Talbot Mills <160 -- 470 <160 e56 990 <160 <600 <3 <3 <1517 Mill River <58 -- e22 <58 e10 e48 <58 <200 <1 <1 <518 Windsor Reservoir <64 -- 200 <64 e26 200 <64 <200 <1 <1 <519 Mill Pond <80 e830 1,200 <80 e52 1,100 <80 <200 <1 <1 <520 Mill Pond #1 <290 -- 1,100 <290 e110 1,900 <290 <1,200 <6 <6 <3021 Rice City Pond <70 -- 690 e41 e190 1,400 <70 <200 4 2 <522 Assabet River <140 -- 620 <140 e120 1,200 <140 <400 e2 e1 <1023 Upper Flints Pond <100 -- e38 <100 e29 e49 <100 <400 <2 <2 <1024 Stony Brook <330 -- e170 <330 e190 e290 <330 <1,200 <6 <6 <3025 Tel Electric Pond <85 -- 7,400 120 e94 11,000 <85 <200 4 3 <526 Monument Pond #2 <66 e570 e58 <66 e37 e32 e23 <200 <1 <1 <527 Town Brook #1 <120 -- 2,900 <120 e69 3,200 e43 <500 <2 <2 <1228 Deleano Pond <650 e1,500 730 <650 e460 1,700 <650 <2,600 e8 e8 <6529 Worcester Consolidated Station <65 -- 2,500 <65 160 3,000 <65 <200 e3 <1 <530 Cooks Canyon Lower Pond <75 -- 1,100 <75 e76 1,600 <75 <200 1 M <531 Unnamed, Stony Brook <430 -- e130 <430 e610 e220 <430 <1,600 <8 <8 <4032 Unnamed, Winnetuxet <300 -- e61 <300 e38 e85 <300 <1,200 <6 <6 <30
THIS PAGE INTENTIONALLY LEFT BLANK
Prepared by the Pembroke Publishing Service Center.

For more information concerning this report, contact:

Office Chief

U.S. Geological Survey

New England Water Science Center

Massachusetts-Rhode Island Office

10 Bearfoot Road

Northborough, MA 01532

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Breault and others—Estimated Sediment Thickness, Quality, and Toxicity to Benthic Organisms in Selected Impoundments in Massachusetts—SIR 2012–5191

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