As a part of the U.S. Geological Survey National Water-Quality Assessment

(NAWQA) Program, hydrologic and

water-quality assessment of the Upper

Colorado River Basin (UCOL) study unit

began in 1994. Prior to the design of the

integrated studies of water quality in the

basin, a retrospective investigation was

conducted to determine the availability of

historical water-quality data and the location of previous research that occurred in

the UCOL. The findings indicated that

minimal data had been collected regarding the occurrence and distribution of

organochlorine pesticides and polychlorinated biphenyls (PCB’s) in streambed

sediment and whole-body fish in the

UCOL study unit (Deacon and Stephens,

1996).

Organochlorine pesticides and

PCB’s, all of which are organochlorine

compounds, have been specifically targeted by standards and guidelines that

exist to protect water quality for human

and wildlife health. In 1995–96, a survey

of selected organochlorine pesticides and

PCB’s was conducted in the UCOL to

(1) determine their distribution and concentrations in streambed sediment and

whole-body fish, and (2) compare these

concentrations to established waterquality guidelines.

Organochlorine compounds are

unique because their presence can result

only from human activities. These compounds disperse from their original point

of application, typically agricultural fields

and urban areas, to the hydrologic system

through soil erosion, runoff, and precipitation. Due to the persistence, bioaccumulation, and hazards of these compounds,

the use of many organochlorine pesticides

has been banned or severely restricted in

the United States. Organochlorine compounds are extremely persistent in the

environment and have the unique

property of concentrating in sediment

and in the fatty tissue of aquatic life

(Ware, 1989).

This fact sheet presents data for

detections of selected organochlorine

compounds in streambed sediment and

whole-body fish. Data for all the compounds detected in samples collected for

this study are in the U.S. Geological Survey National Water Information System

(NWIS) data base.

Description of Sampling Unit

and Study Approach

The UCOL study unit (fig. 1)

encompasses about 17,800 square miles

and has varied climate, geology, hydrology, soils, topography, and land uses.

Water quality throughout the basin is

directly affected by these natural (physiography, altitude, geology, climate, soils)

and human (population, land use, water

allocation and use) factors (Apodaca and

others, 1996). Sampling sites were

selected to characterize differences

among these environmental settings and

various land uses and to acquire addiDistribution and Concentrations of Selected Organochlorine

Pesticides and PCB’s in Streambed Sediment and Whole-Body

Fish in the Upper Colorado River Basin, 1995–96

—by Verlin C. Stephens and Jeffrey R. Deacon

Typical high-elevation stream in the UCOL

study unit.

tional data regarding the occurrence and

distribution of organochlorine compounds. Sampling sites in the eastern part

of the study unit represent a high-altitude

environment of small, clear, cool streams

dominated by forest and rangeland.

Adverse human effects on water quality in

these areas predominantly are mining,

increasing urban development, recreational use, and hydrologic modifications

(dams and diversions). Sampling sites in

the western part of the study unit are representative of a more arid climate dominated by larger, warmer, sediment-laden

streams. Human effects on water quality
10/10/95

10/05/95

10/05/95

10/10/95

Site

number

(fig. 1) 

Sample

collection

date,

streambed

sediment 

10/13/95

10/13/95

10/13/95

10/12/95

10/10/95

10/11/95

10/11/95

10/12/95

10/12/95

10/12/95

09/17/96

09/17/96

09/17/96

11/20/95

Colorado River below Baker Gulch

French Gulch near Breckenridge 

Blue River below French Gulch

Gore Creek at mouth near Minturn

Site name

East River below Cement Creek

Gunnison River at County Road 32

Gunnison River below Gunnison Tunnel

Uncompahgre River near Ridgway

Colorado River at Dotsero

Dry Fork at upper station near De Beque

Colorado River near Cameo

Dry Creek near Begonia Road

Tongue Creek near Cory, CO

Gunnison River near Grand Junction

33 Road drain near mouth

Appleton drain near mouth

Copeco drain near mouth

Reed Wash near Mack

Colorado River near Colorado-Utah

 State line 

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

09010500

09046530

392944106024400

09066510

Site identifier

09112200

383103106594200

09128000

09146200

09070500

09095300

09095500

09149480

09144200

09152500

390347108265800

390624108374900

390723108400500

09153290

09163500

Reference

Mining

Mining

Urban/Recreation

Site type

Urban/Recreation

Mixed

Reference

Mining

Mixed

Reference

Mixed

Agriculture

Agriculture

Mixed

Agricultural drain

Agricultural drain

Agricultural drain

Agriculture

Mixed 10/11/95

08/17/95

na

08/25/95

08/15/95

Sample

collection

date,

whole-fish

tissue 

10/16/95

08/16/95

09/21/95

10/17/95

08/23/95

na

08/23/95

08/18/95

08/24/95

08/16/95

na

na

na

11/21/95

08/17/95

53

11

69

102

Drainage

area

(mi2) 

238

2,128

3,965

149

4,394

97

8,050

175

200

7,928

na

na

na

16

17,843

Brown trout

No fish found

Brown trout

Brown trout

Type of wholebody-fish sample

used for analysis

Brown trout

Brown trout

Brown trout

White sucker

Brown trout 

No fish found

Bluehead sucker

White sucker

White sucker 

Bluehead sucker

No fish collected

No fish collected

No fish collected

Flannelmouth 

 sucker

Bluehead sucker

in these areas are predominantly agriculture, water development, and increasing

urban development and recreational use.

Streambed-sediment and wholebody-fish samples were collected in fall

1995 and 1996 (fig. 1, table 1) for analysis

of concentrations of organochlorine pesticides and PCB’s. Nineteen sites were

sampled for streambed sediment and analyzed for 33 organochlorine pesticides

and PCB’s. Whole-body-fish samples

were collected by electroshocking at 14 of

the sampling sites and were analyzed for

28 organochlorine pesticides and PCB’s.

Five of the sites sampled for streambed

sediment did not contain, or were not

sampled, for fish (table 1). Samples of

streambed sediment and whole-body fish

were collected, processed, and analyzed

in accordance with NAWQA protocols

(Crawford and Luoma, 1993; Shelton and

Capel, 1994). Sample collection was limited to stream reaches that averaged 150–

200 meters (m) in length for each of the

wadeable sampling sites and 500–750 m

in length for the non-wadeable sites.

Twenty to 25 individual subsamples of

streambed sediment from the upper 2 centimeters were collected from a variety of

undisturbed, continuously wetted depositional zones. The subsamples were composited into a glass container, homogenized, and sieved to < 2 millimeters.

The samples were then frozen and

shipped to a laboratory for analysis. Each

of the whole-body-fish samples collected

consisted of a composite of seven similarly sized fish of the same species. The

predominant species collected in the eastern higher altitudes was brown trout and

the predominant species collected in the

western lower reaches of the basin was

the sucker. Each fish collected was

weighed, measured, sexed, and aged. Fish

also were closely scrutinized for signs of

disease, parasites, or other abnormal

features. Samples were prepared for the

organochlorine and PCB analyses by

wrapping the individual whole fish in

aluminum foil, freezing the sample, and

shipping to the laboratory for analysis.

Bed-sediment sample collection.

Table 1. Sampling-site information

[Sites listed indicate collection of streambed-sediment samples and type of whole-body-fish samples as noted; na, not available; mi2, square miles]
Grand

Junction

Montrose

Gunnison

Glenwood

Springs

Delta

UTAH

COLORADO

Upper Colorado River Basin study unit

UTAH

COLORADO

106°

107°

40°

108°

109°

39°

38° 0

0 20 40 KILOMETERS

20 40 MILES

EXPLANATION

URBAN

AGRICULTURE

RANGELAND

FOREST

WATER

BARREN/ALPINE

SAMPLING SITES FOR

 STREAMBED SEDIMENT

 AND WHOLE-BODY FISH

SAMPLING SITES FOR 

 STREAMBED SEDIMENT

Electroshocking from a boat at a non-wadeable

site.

Established Guidelines

The Provincial Sediment Quality

Guidelines (PSQG) (Environment Canada, 1995) were used to compare concentrations of organochlorine pesticides and

PCB’s in streambed-sediment samples

collected in this study. These guidelines

are based on chronic and long-term

effects of contaminant concentrations on

benthic organisms. The PSQG establish

two assessment values for some of the

organochlorine and PCB contaminants

analyzed in this study: the lower threshold

effect level (TEL) and the higher probable

effect level (PEL). The TEL represents

the guideline concentration of sediment

contamination below which adverse

effects are expected to rarely occur. The

PEL represents the guideline concentration above which adverse effects are

expected to frequently occur. Concentrations that fall between the TEL and PEL

are levels at which adverse effects are

expected to occasionally occur (Environment Canada, 1995). The only national

guidelines available for evaluating organochlorine-compound concentrations in

whole-body fish have been established by

the National Academy of Sciences and

Figure 1. Land use and sampling site locations in the Upper Colorado River Basin Study Unit.
National Academy of Engineering (NAS/

NAE). These guidelines apply to the protection of wildlife that consume fish

(National Academy of Sciences and

National Academy of Engineering, 1973).

Major Organochlorine

Compounds Detected in

Relation to Established

Guidelines

Dichloro diphenyl trichloroethane (DDT): DDT is a welldocumented, persistent organochlorine

compound that has been banned from use

in the United States since 1972. The six

degradation products of DDT were analyzed for, and the sum of the individual

concentrations are denoted as total DDT

in this fact sheet. Total DDT was detected

in streambed-sediment samples at 7 of

19 sites and in whole-body-fish samples at

12 of 14 sites (fig. 2). DDT was the most

frequently detected organochlorine compound, with the highest concentrations

found in the UCOL study unit. The highest concentrations detected in streambedsediment samples were collected from

sites 15, 16, and 17, which are agricultural

drains. Concentrations of the samples collected at these sites exceeded the PSQG

TEL of 6.98 μg/kg (micrograms per kilogram) for total DDT. None of the sites

exceeded the PEL of 4,450 μg/kg.

Samples collected at sites 3 and 7

had no detections of total DDT in wholebody fish. Samples collected at site 1, a

reference site (a reference site is one that

is used to determine background or naturally occurring water-quality conditions)

had a total DDT concentration of 11 μg/kg

in whole-body fish. This concentration

was higher than other samples collected in

the eastern, higher altitude sampling sites

and might be attributed to residues from

applications of DDT to forested areas for

the control of spruce budworm in the

1950’s (L.F. Carter, U.S. Geological

Survey, written commun., 1997). Total

DDT concentrations in whole-body fish

were highest at agricultural and mixed

land-use sites. The concentration of total

DDT in whole-body-fish samples collected at site 12 (983 μg/kg), an agricultural site, approached the NAS/NAE

guideline of 1,000 μg/kg for the protection

of wildlife that consume fish.

Dichloro diphenyl dichloroethylene (p,p'-DDE): P,p'-DDE is a

degradation by-product of DDT and has

separate PSQG guidelines established for

concentrations of this individual isomer in

streambed sediment. Of the seven samples

collected that had detections in

streambed sediment, all concentrations

exceeded the TEL (1.42 μg/kg). Sample

concentrations at two agricultural drain

sites (site 15, 56 μg/kg; site 17, 19 μg/kg)

greatly exceeded the PEL (6.75 μg/kg)

(fig. 3). All seven of these samples were

collected from agricultural and mixed

land-use sites in the western part of the

study unit. P,p'-DDE also was detected in

12 of 14 samples collected for wholebody fish; however, none of the concentrations exceeded NAS/NAE guidelines.

Chlordane: Chlordane is highly toxic

to fish and historically was used as a contact insecticide until 1980 when it was

banned except for termite control and

wood treatment. In this fact sheet, the sum

of the chlordane isomers (cis-chlordane,

trans-chlordane, cis-nonachlor, transnonachlor, oxychlordane, and heptachlor

epoxide) is referred to as “total chlordane.” None of the chlordane isomers

were detected in streambed-sediment

samples, but some were detected in

whole-body-fish samples collected at

some agricultural and mixed land-use

sites (fig. 2). Total chlordane concentrations for whole-body-fish samples ranged

from 25.2 to 86.4 μg/kg. Whole-body-fish

samples collected at site 18, an agricultural land-use site, had the highest total

chlordane concentration (86.4 μg/kg) and

approached the NAS/NAE guideline for

whole-body fish of 100 μg/kg.

Polychlorinated Biphenyls

(PCB’s): PCB’s are well-documented,

persistent organochlorine compounds that

have been banned since 1979. Historically, these compounds primarily were

used as industrial heat-exchange and

dielectric fluids used in capacitors and

transformers. PCB’s were detected only

10 11 12 13 14 15 16 17 18 19

SITE NUMBER

(CORRESPONDS TO SITE NUMBER IN TABLE 1 AND FIGURE 1)

CONCENTRATION, IN MICROGRAMS

PER KILOGRAM

1 2 3 4 5 6 7 8 9 1

TEL

PSQG

PEL

NAS/NAE

guideline

10

100

1,000

p,p'-DDE in streambed sediment

p,p'-DDE in whole-body fish

Figure 2. Concentrations of total DDT and total chlordane in streambed sediment and wholebody fish.

Figure 3. Concentrations of p,p'-DDE in streambed sediment and whole-body fish.

1

1,000

100

10

1 2 3 4 5 6 7 8 9 10

SITE NUMBER

(CORRESPONDS TO SITE NUMBER IN TABLE 1 AND FIGURE 1)

CONCENTRATION, IN MICROGRAMS

11 12 13 14 15 16 17 18 19

PER KILOGRAM

NAS/NAE

guideline

DDT

NAS/NAE

guideline

chlordane

PSQG

TEL DDT

Total DDT in streambed sediment

Total DDT in whole-body fish

Total chlordane in whole-body fish
in whole-body-fish samples at site 8

(fig. 4), a mining land-use site, with a

concentration of 180 μg/kg. The NAS/

NAE guideline for whole-body fish is

500 μg/kg.

Dieldrin: Dieldrin also has been

banned from use in the United States. The

PSQG guidelines for dieldrin are a TEL

of 2.85 and PEL of 6.67 μg/kg. Dieldrin

was detected in streambed sediment at

two agricultural drain sites (15 and 16);

however, only site 15 exceeded the TEL

guideline with a concentration of

3.5 μg/kg (fig. 4). Dieldrin was the second

most frequently detected organochlorine

compound (5 of 14 sites) in whole-bodyfish samples. Concentrations of dieldrin

in whole-body-fish samples occurred predominantly at agricultural land-use sites,

and concentrations at all sites ranged from

6.0 to 71 μg/kg. The highest concentration of 71 μg/kg from site 12 was less

than the NAS/NAE guideline of 100 μg/

kg.

Dacthal (DCPA): Dacthal, more

commonly known as DCPA, is used as a

selective preemergent herbicide. It is considered a general hazard to fish and is the

only compound analyzed for and detected

in this study that has not been banned

from use. DCPA was detected in trace

amounts in streambed-sediment samples

collected at agricultural sites. The

streambed-sediment sample collected

from site 17 had the highest concentration

at 10 μg/kg (fig. 5). DCPA was detected

in whole-body-fish samples at three sites

(12, 14, and 19) with concentrations

ranging from 32 to 52 μg/kg. There are no

established guidelines for concentrations

of DCPA in streambed sediment or

whole-body fish.

Toxaphene: Toxaphene (Camphechlor) was widely used as a preharvest

insecticide for cotton, grains, vegetables,

and fruit. Toxaphene was banned in 1982

after it was used to replace DDT as an

agricultural insecticide. Toxaphene was

only detected in whole-body-fish samples

(fig. 5) at site 18 (300 μg/kg), an intensive

agricultural land-use site. Concentration

at this site exceeded the NAS/NAE guideline (100 μg/kg) for toxaphene concentrations in whole-body fish.

Water-Quality Implications

Organochlorine pesticides and

PCB’s were more frequently detected and

were at much higher concentrations in

whole-body-fish samples than in

streambed-sediment samples. Six of

33 individual organochlorine compounds

analyzed for were detected in streambedsediment samples. Eighteen of the

28 individual organochlorine compounds

analyzed for were detected in wholebody-fish samples. Although the use of

organochlorine compounds such as DDT,

chlordane, and PCB’s was discontinued in

the early 1970’s, all of these compounds

were detected in whole-body-fish samples

and, to a much lesser extent, in streambed-sediment samples collected in the

UCOL study unit. The sites with the most

detections and highest concentrations of

organochlorine compounds in streambedsediment and whole-body-fish samples

generally were located in the western,

lower reaches of the basin, which includes

some mixed land use but which generally

is agricultural.

Site 12 had the most detections of

organochlorine compounds in streambedsediment and whole-body-fish samples.

Site 15 was sampled only for streambed

sediment but had concentrations of a degradational form of DDT (p,p'-DDE) that

exceeded PSQG guidelines by more than

eight times the PEL. In addition, all other

organochlorine compounds detected in

streambed sediment at this site exceeded

the TEL, and some exceeded the PEL.

Concentrations of toxaphene in wholebody-fish samples collected from site 12

exceeded levels established for the protection of wildlife that consume fish.

Weighing and measuring of individual fish.

Figure 4. Concentrations of PCB’s and dieldrin in streambed sediment and whole-body fish.

Figure 5. Concentrations of DCPA and toxaphene in streambed sediment and whole-body fish.

1

1,000

100

10

1 2 3 4 5 6 7 8 9 10

SITE NUMBER

(CORRESPONDS TO SITE NUMBER IN TABLE 1 AND FIGURE 1)

CONCENTRATION, IN MICROGRAMS

11 12 13 14 15 16 17 18 19

PER KILOGRAM

NAS/NAE

guideline

dieldrin

NAS/NAE

guideline

PCB's

PSQG

PEL

dieldrin

TEL

dieldrin

Dieldrin in streambed sediment

Dieldrin in whole-body

 fish

Total PCB's in whole-

 body fish

1

1,000

100

10

1 2 3 4 5 6 7 8 9 10

SITE NUMBER

(CORRESPONDS TO SITE NUMBER IN TABLE 1 AND FIGURE 1)

11 12 13 14 15 16 17 18 19

CONCENTRATION, IN MICROGRAMS

PER KILOGRAM

NAS/NAE

guideline

toxaphene DCPA in streambed sediment

DCPA in whole-body fish

Toxaphene in whole-body fish
Fact Sheet FSInformation on technical reports and hydrologic

data related to the NAWQA Program

can be obtained from:

Upper Colorado River NAWQA Manager

U.S. Geological Survey,

Water Resources Division

Bldg. 53, Denver Federal Center

Mail Stop 415, Box 25046

Denver, CO 80225–0046

email: nedriver@usgs.gov

Assessing the implications of organochlorine pesticide and PCB concentrations in fish and wildlife is becoming

increasingly important because of recent

evidence suggesting that some organochlorine compounds may disrupt endocrine systems, even at low concentrations

(Colburn and others, 1993). Also, the

cumulative or synergistic effects associated with multiple occurrences of toxic

compounds are not well understood or

documented. Although most of the organochlorine compounds detected in the

samples from the study have been banned,

the environmental degradation of these

compounds is slow; therefore, organochlorine compounds such as DDT,

chlordane, and PCB’s remain in the

UCOL study unit long after use has been

restricted.

References Cited

Apodaca, L.E., Driver, N.E., Stephens,

V.C., and Spahr, N.E., 1996, Environmental setting and implications

on water quality, Upper Colorado

River Basin, Colorado and Utah:

U.S. Geological Survey WaterResources Investigations Report

95–4263, 34 p.

Colburn, T., van Saal, F.S., and Soto,

A.M., 1993, Developmental effects

of endocrine-disrupting chemicals in

wildlife and humans: Environmental

Health Perspectives, v. 101; p. 378–

384.

Crawford, J.K., and Luoma, S.N., 1993,

Guidelines for studies of contaminants in biological tissues for the

National Water-Quality Assessment

Program: U.S. Geological Survey

Open-File Report 92–494, 69 p.

Deacon, J.R., and Stephens, V.C., 1996,

Summary of biological and contaminant investigations related to stream

water quality and environmental

setting in the Upper Colorado River

Basin, 1938–95: U.S. Geological

Survey Water-Resources Investigations Report 96–4172, 37 p.

Environment Canada, 1995, Interim sediment quality guidelines: Ottawa,

Ontario, Ecosystem Conservation

Directorate Evaluation and Interpretation Branch, 63 p.

National Academy of Sciences and

National Academy of Engineering,

1973, Water quality criteria, 1972:

U.S. Environmental Protection

Agency, EPA R3–73–033, 594 p.

Shelton, L.R., and Capel, P.D., 1994,

Guidelines for collecting and processing samples of streambed

sediment for analysis of trace elements and organic contaminants for

the National Water-Quality Assessment Program: U.S. Geological Survey Open-File Report 94–458, 20 p.

Ware, G.W., 1989, The pesticide book:

Fresno, Calif., Thomson Publications, 3d ed., 340 p.

Whole-body-fish sample processing.

March 1998 167-97

Manuscript layout and design: Alan M. Duran

Final illustrations: Alan M. Duran