A Synoptic Study of Fecal-Indicator Bacteria in the 

Wind River, Bighorn River, and Goose Creek Basins, 

Wyoming, June-July 2000

Water-Resources Investigations Report 03-4055

Prepared as part of the

NATIONAL WATER-QUALITY ASSESSMENT PROGRAM

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY
U.S. Department of the Interior

U.S. Geological Survey

A Synoptic Study of Fecal-Indicator Bacteria in the 

Wind River, Bighorn River, and Goose Creek Basins, 

Wyoming, June-July 2000

By Melanie L. Clark and Merry E. Gamper

Water-Resources Investigations Report 03-4055

Prepared as part of the 

NATIONAL WATER-QUALITY ASSESSMENT PROGRAM

Cheyenne, Wyoming

2003
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

Any use of trade, product, or firm names in this publication is for 

descriptive purposes only and does not imply endorsement by the 

U.S. Government

For additional information write to:

District Chief

U.S. Geological Survey, WRD

2617 E. Lincolnway, Suite B

Cheyenne, Wyoming 82001-5662

Copies of this report can be purchased from:

U.S. Geological Survey

Branch of Information Services

Box 25286, Denver Federal Center

Denver, Colorado 80225

Information regarding the National Water-Quality Assessment (NAWQA) Program is available on the Internet via the 

World Wide Web. You may connect to the NAWQA Home Page using the Universal Resource Locator (URL): 

<http://wwwrvares.er.usgs.gov/nawqa/nawqa_home.html>
 iii

FOREWORD

The U.S. Geological Survey (USGS) is committed to 

serve the Nation with accurate and timely scientific 

information that helps enhance and protect the overall 

quality of life, and facilitates effective management of 

water, biological, energy, and mineral resources. 

(http://www.usgs.gov/). Information on the quality of the 

Nation’s water resources is of critical interest to the 

USGS because it is so integrally linked to the long-term 

availability of water that is clean and safe for drinking 

and recreation and that is suitable for industry, irrigation, 

and habitat for fish and wildlife. Escalating population 

growth and increasing demands for the multiple water 

uses make water availability, now measured in terms of 

quantity and quality, even more critical to the long-term 

sustainability of our communities and ecosystems.

The USGS implemented the National Water-Quality 

Assessment (NAWQA) Program to support national, 

regional, and local information needs and decisions 

related to water-quality management and policy. 

(http://water.usgs.gov/nawqa/). Shaped by and 

coordinated with ongoing efforts of other Federal, State, 

and local agencies, the NAWQA Program is designed to 

answer: What is the condition of our Nation’s streams 

and ground water? How are the conditions changing over 

time? How do natural features and human activities 

affect the quality of streams and ground water, and where 

are those effects most pronounced? By combining 

information on water chemistry, physical characteristics, 

stream habitat, and aquatic life, the NAWQA Program 

aims to provide science-based insights for current and 

emerging water issues and priorities. NAWQA results 

can contribute to informed decisions that result in 

practical and effective water-resource management and 

strategies that protect and restore water quality.

Since 1991, the NAWQA Program has implemented 

interdisciplinary assessments in more than 50 of the 

Nation’s most important river basins and aquifers, 

referred to as Study Units. (http://water.usgs.gov/nawqa/

nawqamap.html). Collectively, these Study Units 

account for more than 60 percent of the overall water use 

and population served by public water supply, and are 

representative of the Nation’s major hydrologic 

landscapes, priority ecological resources, and 

agricultural, urban, and natural sources of contamination. 

Each assessment is guided by a nationally consistent 

study design and methods of sampling and analysis. The 

assessments thereby build local knowledge about waterquality issues and trends in a particular stream or aquifer 

while providing an understanding of how and why water 

quality varies regionally and nationally. The consistent, 

multi-scale approach helps to determine if certain types 

of water-quality issues are isolated or pervasive, and 

allows direct comparisons of how human activities and 

natural processes affect water quality and ecological 

health in the Nation’s diverse geographic and 

environmental settings. Comprehensive assessments on 

pesticides, nutrients, volatile organic compounds, trace 

metals, and aquatic ecology are developed at the national 

scale through comparative analysis of the Study-Unit 

findings. (http://water.usgs.gov/nawqa/natsyn.html). 

The USGS places high value on the communication and 

dissemination of credible, timely, and relevant science so 

that the most recent and available knowledge about water 

resources can be applied in management and policy 

decisions. We hope this NAWQA publication will 

provide you the needed insights and information to meet 

your needs, and thereby foster increased awareness and 

involvement in the protection and restoration of our 

Nation’s waters. 

The NAWQA Program recognizes that a national 

assessment by a single program cannot address all waterresource issues of interest. External coordination at all 

levels is critical for a fully integrated understanding of 

watersheds and for cost-effective management, 

regulation, and conservation of our Nation’s water 

resources. The Program, therefore, depends extensively 

on the advice, cooperation, and information from other 

Federal, State, interstate, Tribal, and local agencies, nongovernment organizations, industry, academia, and other 

stakeholder groups. The assistance and suggestions of all 

are greatly appreciated.

Robert M. Hirsch 

Associate Director for Water
CONTENTS v

CONTENTS

Page

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

Introduction........................................................................................................................................................................... 2

Background ................................................................................................................................................................. 2

Purpose and scope....................................................................................................................................................... 5

Acknowledgments....................................................................................................................................................... 5

Environmental setting ........................................................................................................................................................... 5

Sampling sites and methods.................................................................................................................................................. 7

Field measurements and sample collection................................................................................................................. 7

Data analysis ............................................................................................................................................................... 8

Microbial source tracking ........................................................................................................................................... 15

Synoptic-study results ........................................................................................................................................................... 15

Sampling conditions.................................................................................................................................................... 15

Quality-control samples .............................................................................................................................................. 22

Distribution of fecal-indicator bacteria by basin......................................................................................................... 23

Wind River Basin .............................................................................................................................................. 28

Bighorn River Basin.......................................................................................................................................... 30

Goose Creek Basin............................................................................................................................................ 32

Distribution of fecal-indicator bacteria by land cover................................................................................................. 35

Relation of Escherichia coli to fecal coliform ............................................................................................................ 36

Relation of fecal-indicator bacterial to water-quality characteristics.......................................................................... 36

Microbial source tracking ........................................................................................................................................... 39

Summary ............................................................................................................................................................................... 40

References............................................................................................................................................................................. 41

FIGURES

1. Map showing location of the Wind River, Bighorn River, and Goose Creek Basins in the Yellowstone 

River Basin........................................................................................................................................................ 3

2. Graph showing relative distribution of land cover in the Wind River, Bighorn River, and Goose Creek 

Basins, Wyoming .............................................................................................................................................. 7

3-5. Map showing:

3. Location of sampling sites in the Wind River Basin, Wyoming, July 2000.................................................. 9

4. Location of sampling sites in the Bighorn River Basin, Wyoming, July 2000 ............................................. 10

5. Location of sampling sites in the Goose Creek Basin, Wyoming, June 2000............................................... 11

6. Annual hydrographs and streamflows for terminal sites during a synoptic study in the Wind River, 

Bighorn River, and Goose Creek Basins, Wyoming, 2000 ............................................................................... 24

7. Graph showing historical and synoptic-study fecal-coliform concentrations for selected sites in the 

Wind River, Bighorn River, and Goose Creek Basins, Wyoming, 1991-2000 ................................................. 25

8. Graph showing fecal-indicator-bacteria concentrations for the Wind River, Bighorn River, and Goose 

Creek Basins, Wyoming, June-July 2000 ......................................................................................................... 27

9-11. Map showing:

9. Fecal-indicator-bacteria concentratons for samples collected in the Wind River Basin, 

Wyoming, July 2000 ................................................................................................................................ 29

10. Fecal-indicator-bacteria concentration for samples collected in the Bighorn River Basin, 

Wyoming, July 2000 ................................................................................................................................ 31

11. Fecal-indicator-bacteria concentrations for samples collected in the Goose Creek Basin, 

Wyoming, June 2000................................................................................................................................ 34
vi A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

CONTENTS--Continued

Page

12-14. Graph showing:

12. Fecal-indicator-bacteria concentrations by land-cover classification in the Wind River, Bighorn River, 

and Goose Creek Basins, Wyoming, June-July 2000.............................................................................. 37

13. Fecal-coliform and Escherichia coli relations in the Wind River, Bighorn River, and Goose Creek 

Basins, Wyoming, June-July 2000 .......................................................................................................... 38

14. Source determinations of Escherichia coli isolates for samples from the Bighorn River at Basin, 

Wyoming (site 52) and Bitter Creek near Garland, Wyoming (site 71) in the Bighorn River Basin, 

Wyoming, July 2000................................................................................................................................ 40

TABLES

1. Minimum and maximum mean monthly air temperatures for climate stations in the Wind River, 

Bighorn River, and Goose Creek Basins, Wyoming ........................................................................................ 6

2. Site information for sampling sites in the Wind River, Bighorn River, and Goose Creek Basins, 

Wyoming, June-July 2000................................................................................................................................ 12

3. Streamflow, physical-characteristics, and fecal-indicator-bacteria results for the Wind River, 

Bighorn River, and Goose Creek Basins, Wyoming, June-July 2000.............................................................. 16

4. Period of record for fecal-coliform concentrations for selected sites in the Wind River, Bighorn River, 

and Goose Creek Basins, Wyoming, 1991-2000.............................................................................................. 26

5. Concentrations and relative percent difference of replicate quality-control samples of fecal-indicator 

bacteria in the Wind River, Bighorn River, and Goose Creek Basins, Wyoming, June-July 2000.................. 26

6. Estimated human and livestock population densities for the Wind River, Bighorn River, and Goose 

Creek Basins, Wyoming, 2000......................................................................................................................... 27

7. Fecal-indicator-bacteria concentrations exceeding the U.S. Environmental Protection Agency’s 

recommended limits for a single sample for recreational contact with water for samples in the 

Wind River, Bighorn River, and Goose Creek Basins, Wyoming, June-July 2000.......................................... 28

8. Sites where sample concentrations of fecal-indicator bacteria exceeded the U.S. Environmental Protection 

Agency’s recommended limits for a single sample for recreational contact with water in the 

Wind River Basin, Wyoming, July 2000.......................................................................................................... 30

9. Sites where sample concentrations of fecal-indicator bacteria exceeded the U.S. Environmental Protection 

Agency’s recommended limits for a single sample for recreational contact with water in the 

Bighorn River Basin, Wyoming, July 2000 ..................................................................................................... 33

10. Sites where sample concentrations of fecal-indicator bacteria exceeded the U.S. Environmental Protection 

Agency’s recommended limits for a single sample for recreational contact with water in the 

Goose Creek Basin, Wyoming, June 2000....................................................................................................... 35

11. Sampling sites by land cover in the Wind River, Bighorn River, and Goose Creek Basins, 

Wyoming, June-July 2000................................................................................................................................ 35

12. Spearman’s rank correlation coefficients between fecal-indicator bacteria and water-quality constituents 

in the Wind River, Bighorn River, and Goose Creek Basins, Wyoming, June-July 2000................................ 39
CONTENTS vii

CONVERSION FACTORS

Multiply By To obtain

millimeter (mm) 0.03937 inch

kilometer (km) 0.6214 mile

square kilometer (km2) 0.3861 square mile

cubic meter (m3) 35.31 cubic foot (ft3)

cubic meter per second (m3/s) 35.31 cubic foot per second (ft3/s)

kilogram 2.205 pound (lb)

Temperature can be converted to degrees Fahrenheit (oF) or degrees Celsius (oC) as follows:

oF = 9/5(oC) + 32

oC = 5/9(oF - 32)

Abbreviated water-quality units used in this report:

col/100 mL colonies per 100 milliliters

μm micrometer

mg/L milligrams per liter

mL milliliters

NTU nephelometric turbidity units

μS/cm microsiemens per centimeter at 25 degrees Celsius

< less than

> greater than

Abbreviations used in this report:

EPA U.S. Environmental Protection Agency

NAWQA National Water-Quality Assessment Program

NLCD National Land Cover Data

RPD Relative percent difference

USGS U.S. Geological Survey

WDEQ Wyoming Department of Environmental Quality

YRB Yellowstone River Basin
ABSTRACT 1

ABSTRACT

A synoptic study of fecal-indicator bacteria 

was conducted during June and July 2000 in the 

Wind River, Bighorn River, and Goose Creek 

Basins in Wyoming as part of the U.S. Geological 

Survey’s National Water-Quality Assessment Program for the Yellowstone River Basin. Fecalcoliform concentrations ranged from 2 to 

3,000 col/100 mL (colonies per 100 milliliters) for 

100 samples, and Escherichia coli concentrations 

ranged from 1 to 2,800 col/100 mL for 97 samples. 

Fecal-coliform concentrations exceeded the U.S. 

Environmental Protection Agency’s recommended 

limit for a single sample for recreational contact 

with water in 37.0 percent of the samples. Escherichia coli concentrations exceeded the U.S. Environmental Protection Agency’s recommended limit for 

a single sample for moderate use, full-body recreational contact with water in 38.1 percent of the 

samples and the recommended limit for infrequent 

use, full-body recreational contact with water in 

24.7 percent of the samples.

Fecal-indicator-bacteria concentrations varied by basin. Samples from the Bighorn River Basin 

had the highest median concentrations for fecal 

coliform of 340 col/100 mL and for Escherichia coli

of 300 col/100 mL. Samples from the Wind River 

Basin had the lowest median concentrations for 

fecal coliform of 50 col/100 mL and for Escherichia 

coli of 62 col/100 mL. 

Fecal-indicator-bacteria concentrations varied by land cover. Samples from sites with an urban 

land cover had the highest median concentrations 

for fecal coliform of 540 col/100 mL and for Escherichia coli of 420 col/100 mL. Maximum concentrations for fecal coliform of 3,000 col/100 mL and for 

Escherichia coli of 2,800 col/100 mL were in samples from sites with an agricultural land cover. The 

lowest median concentrations for fecal coliform of 

130 col/100 mL and for Escherichia coli of 

67 col/100 mL were for samples from sites with a 

forested land cover. 

A strong and positive relation existed 

between fecal coliform and Escherichia coli (Spearman’s Rho value of 0.976). The majority of the 

fecal coliforms were Escherichia coli during the 

synoptic study. Fecal-indicator-bacteria concentrations were not correlated to streamflow, water temperature, dissolved oxygen, pH, specific conductance, and alkalinity. Fecal-indicator-bacteria concentrations were moderately correlated with turbidity (Spearman’s Rho values of 0.662 and 0.640 for 

fecal coliform and Escherichia coli, respectively) 

and sediment (Spearman’s Rho values of 0.628 and 

0.636 for fecal coliform and Escherichia coli, 

respectively). 

Escherichia coli isolates analyzed by discriminant analysis of ribotype patterns for samples from 

the Bighorn River at Basin, Wyoming, and Bitter 

Creek near Garland, Wyoming, in the Bighorn River 

Basin were determined to be from nonhuman and 

human sources. Using a confidence interval of 

90 percent, more of the isolates from both sites were 

classified as being from nonhuman than human 

sources; however, both samples had additional isolates that were classified as unknown sources. 

A Synoptic Study of Fecal-Indicator Bacteria in the 

Wind River, Bighorn River, and Goose Creek Basins, 

Wyoming, June-July 2000

By Melanie L. Clark and Merry E. Gamper
2 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

INTRODUCTION

In 1991, the U.S. Geological Survey (USGS) 

began full implementation of the National WaterQuality Assessment (NAWQA) Program. The objectives of the NAWQA Program are to: 1) describe current water-quality conditions for a large part of the 

Nation’s freshwater streams and aquifers; 2) describe 

how water quality is changing over time; and 

3) improve our understanding of the primary natural 

and human factors that affect water-quality conditions. 

In order to achieve these objectives, over 50 Study 

Units containing important river basins and aquifer 

systems were selected that represent diverse hydrogeologic settings and over 60 percent of the national water 

use and population. 

The Yellowstone River Basin (YRB) was selected 

to be one of these NAWQA Study Units. The YRB 

Study Unit consists of the 182,000 km2

 (square kilometers) area that is drained by the Yellowstone River and 

its tributaries, including the Clarks Fork Yellowstone, 

Wind/Bighorn, Tongue, and Powder Rivers. Of the 

total area, 51 percent is in Montana, 48 percent is in 

Wyoming, and 1 percent is in North Dakota (Miller and 

Quinn, 1997). Activities by the NAWQA Program in 

the YRB Study Unit began in 1997. A 3-year intensive 

data-collection period during 1999-2001 included the 

collection of ground-water, stream-water, and biological data. 

The NAWQA Program assesses stream quality 

based on water-column chemistry, bed sediment and 

fish tissue, and ecological studies. Water-column 

chemistry of the YRB was assessed using a fixed-site 

network that included sampling for a wide range of 

constituents with a high sampling frequency at a limited number of sites and synoptic studies that targeted 

selected constituents with a low sampling frequency at 

a large number of sites. A synoptic study to determine 

the distribution of fecal-indicator bacteria was conducted at 100 sites in three basins in the YRB in 

Wyoming—the Wind River, the Bighorn River, and 

the Goose Creek Basins (fig. 1). These basins were 

selected for study because of the known presence of 

fecal-indicator bacteria. Each site was sampled once 

during June-July, 2000. 

Background

Fecal-indicator bacteria, including total coliform, 

fecal coliform, Escherichia coli (E. coli), fecal streptococci, and enterococci, are used to assess the sanitary 

quality of water because their presence can be an indication that contamination by fecal material has 

occurred. Fecal contamination can be from point or 

nonpoint sources. The primary point source of bacterial contamination is sewage treatment outfalls. Nonpoint sources are diffuse in nature and include: 

1) agricultural—animal waste, application of manure 

to fields, crop irrigation from contaminated storage 

ponds; 2) urban/residential—failed septic systems, pet 

waste, landfill leakage; 3) recreational—direct discharge of sewage or waste; and 4) wildlife waste (Wilhelm and Maluk, 1998). 

Fecal-indicator bacteria do not necessarily cause 

illness themselves; however, they are found in association with pathogens. Large levels of fecal-indicator 

bacteria indicate the possible presence of pathogens 

that cause such waterborne diseases as gastroenteritis 

and bacillary dysentery, typhoid fever, and cholera 

(Myers and Sylvester, 1997). Pathogens can pose a 

health risk even at low concentrations. Because of the 

difficulties in analyzing for the actual pathogens, fecalindicator bacteria are widely used to assess the potential for their presence. 

Fecal coliforms commonly are used as the fecalindicator bacteria for determining the sanitary conditions of recreational waters. Fecal coliforms are 

defined as the subgroup of total coliforms able to ferment lactose with the production of gas in 24 hours at 

an incubation temperature of 44.5o

C (Dufour, 1977). 

Despite their name, at least one member of the fecalcoliform group, Klebsiella, has non-fecal sources, 

including pulp and paper mill effluents, textile processing plant effluents, cotton mill wastewaters, and sugar 

beet wastes (U.S. Environmental Protection Agency, 

1986). The presence of E. coli in recreational waters is 

direct evidence that fecal contamination from humans 

or other warm-blooded animals has occurred (Dufour, 

1977; Cabelli, 1977). 

The presence of fecal-indicator bacteria, primarily 

fecal coliform, has been documented in the Wind 

River, Bighorn River, and Goose Creek Basins of the 

YRB. In the Wind River Basin, fecal-coliform concentrations greater than 400 col/100 mL (colonies per 

100 milliliters) occasionally were measured at a site on 
INTRODUCTION 3 Figure 1. Location of the Wind River, Bighorn River, and Goose Creek Basins in the Yellowstone River Basin.

Bighorn River Basin Bighorn River Basin

Wind River Basin Wind River Basin

112 ̊

112 ̊ 110 ̊

110 ̊

108 ̊

108 ̊

106 ̊

106 ̊

104 ̊

104 ̊

102 ̊

102 ̊

100 ̊

100 ̊

114 ̊ 116 ̊

114 ̊

44 ̊ 44 ̊

46 ̊

48 ̊

42 ̊ 42 ̊

00

50

50

100

100

150

150

200

200

250 MILES

250 KILOMETERS

MONTANA

WYOMING

NORTH DAKO

Bighorn River Basin

Wind River Basin

Goose Creek

Basin

Yellowstone River

Basin boundary
4 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

the Little Wind River near Riverton, Wyo. for the 

period 1990-99 (Clark and Norris, 2000). Preliminary 

data prepared for the Popo Agie Conservation District 

indicate fecal-indicator bacteria, including E. coli, 

were found at elevated concentrations in the Middle 

Fork Popo Agie River, a tributary in the Wind River 

Basin (J. States, consultant, written commun., 2001). 

Stream reaches in the Bighorn River and Goose Creek 

Basins were assessed as being impaired by fecal 

coliform for contact recreation in the Wyoming 305(b) 

water-quality assessment for 2000 (Wyoming Department of Environmental Quality, 2000). Additional 

monitoring programs by the State have confirmed the 

presence of fecal coliform in these basins (J. Smith, 

Wyoming Department of Environmental Quality, oral 

commun., 2000). In an interim report prepared for the 

Hot Springs Conservation District and the Wyoming 

Department of Agriculture on a water-quality study in 

Hot Springs County in Wyoming, concentrations of 

fecal coliform exceeding 2,000 col/100 mL were 

reported for Kirby Creek, a tributary to the Bighorn 

River, during 1999 (G. Hurley, consultant, written 

commun., 2000). Concentrations of fecal coliform 

exceeding 1,000 col/100 mL were reported for Bitter 

Creek, a tributary to the Shoshone River in the Bighorn River Basin, during 1977 to 1982 (Wenzel, 

1984). The study cited the Powell Sewage Treatment 

Plant and small private wastewater systems with inadequate construction as sources contributing bacteria to 

Bitter Creek. A water-quality assessment study by the 

Sheridan County Conservation District during 1996 to 

1999 found fecal-coliform concentrations that 

exceeded water-quality criteria in the Tongue River 

drainage near Goose Creek. The concentrations 

exceeded water-quality criteria more often during the 

recreational season (May 1 to September 30) than during the non-recreational season (Sheridan County 

Conservation District, 2000). 

The presence and distribution of fecal-indicator 

bacteria has been related to land-cover characteristics 

in other study areas. Embrey (1992) determined fecalindicator-bacteria concentrations were higher in agricultural and urban settings compared to rangeland and 

forested settings in the Yakima River Basin, Washington. For streams in North and South Carolina, Wilhelm 

and Maluk (1998) found that maximum fecalindicator-bacteria concentrations were within agricultural areas, whereas the highest median concentrations 

were within urban areas. A study of the distribution of 

fecal-indicator bacteria along a gradient of residential 

development in Alaska found urban areas served by 

sewer systems had significantly higher concentrations 

than rural areas served by septic systems; however, differences due to variability in population density could 

not be distinguished (Frenzel and Couvillion, 2002). 

Cattle grazing has been linked to the presence of fecalindicator bacteria in agricultural (Howell and others, 

1995) and rangeland settings (Jawson and others, 1982; 

Sherer and others, 1988; Stephenson and Street, 1978).

Need exists to distinguish between fecal-indicator 

bacteria associated with human waste as opposed to 

other warm-blooded animal waste because human fecal 

wastes represent a greater risk with regard to recreational water quality (Cabelli, 1977). Human feces 

more readily carry enteric pathogens that infect 

humans, including Salmonella spp., Shigella spp., hepatitis A virus, and Norwalk group viruses, compared to 

nonhuman feces (Parveen and others, 1999). However, 

agricultural animals also may carry pathogens that are 

harmful to humans, including E. coli 0157:H7, Salmonella spp., and Shigella spp. (Dombek and others, 

2000). Most basins have multiple host sources, including humans, pets, agricultural animals, and wildlife. 

Historically, a common field technique for differentiating sources of fecal pollution was based on ratios 

of fecal coliform to fecal streptococci; a ratio of greater 

than or equal to 4.0 was used to indicate a human 

source and a ratio less than or equal to 0.7 was used to 

indicate a nonhuman source of fecal material (Geldreich and Kenner, 1969). A later study found the 

source of contamination could not be determined using 

this technique because the ratio was not constant for 

samples from the same origin, and the fecal streptococci test was too general (Pourcher and others, 1991). 

More recent work describes newer techniques for 

microbial source tracking. For example, a field study 

in Puget Sound reported different serotypes of RNA 

coliphages for different fecal sources. Samples from 

streams in a predominantly urban area were serotyped 

as implicating human sources, whereas samples from 

streams in a rural and agricultural area were serotyped 

as implicating nonhumans (Embrey, 2001). Antibiotic 

resistance analysis is another technique used to identify 

sources of bacteria. Because antibiotics are so widely 

used in human and agricultural animals, bacteria from 

these sources develop different patterns of resistance. 

One method of antibiotic resistance analysis uses fecal 

streptococci to differentiate fecal sources (Wiggins, 
ENVIRONMENTAL SETTING 5

1996; Wiggins and others, 1999). A field study using 

this method found that the fecal streptococci were from 

cattle sources in greater than 78 percent of the isolates 

(Hagedorn and others, 1999). Other contributions were 

from waterfowl, deer, and unknown sources. Another 

method of antibiotic resistance analysis uses E. coli to 

differentiate fecal sources. A field study of E. coli isolates from Apalachicola Bay found that E. coli from 

point sources showed greater antibiotic resistance than 

isolates from nonpoint sources, indicating human and 

nonhuman sources, respectively (Parveen and others, 

1997). Two DNA methods for differentiating E. coli

sources are rep-PCR DNA fingerprinting (Dombek and 

others, 2000) and discriminant analysis of ribotype patterns (Parveen and others, 1999; Carson and others, 

2001). A field study in Grand Teton National Park in 

western Wyoming found that isolated colonies of 

E. coli from a stream in the Park contained ribotype 

patterns that matched avian, deer, canine, elk, rodent, 

and human sources (Farag and others, 2001).

Purpose and Scope

This report describes a synoptic study conducted 

in the Wind River, Bighorn River, and Goose Creek 

Basins of the YRB in Wyoming during June-July 2000. 

The objectives of this report are to:

1. Describe the distribution of fecal-indicator bacteria in the Wind River, Bighorn River, and 

Goose Creek Basins. 

2. Describe the distribution of fecal-indicator bacteria as it relates to land cover.

3. Describe the relation between E. coli and fecal 

coliform.

4. Describe the relations between fecal-indicator 

bacteria and other water-quality constituents.

5. Present results for E. coli samples that were analyzed using a microbial source-tracking 

method. 

Acknowledgments

This report resulted from the efforts of many people. The authors graciously thank the Hot Springs, 

Meeteetse, Shoshone, South Bighorn, and Washakie 

Conservation Districts for providing additional funding 

to increase the number of sampling sites in the Bighorn 

River Basin and providing field assistance. The 

authors also thank the Popo Agie, Powell-Clarks Fork, 

and the Sheridan County Conservation Districts, 

Lower Wind River Natural Resource District, U.S. Forest Service, Wind River Environmental Quality Council, and the Wyoming Department of Environmental 

Quality for their assistance in site determinations. 

Thanks are extended to the USGS people that helped 

with the field work for this study, including Eric 

Blajszczak, Jason Feltner, Nathan Majerus, Kirk 

Miller, Thomas Pointon, Wilfrid Sadler, Karen 

Watson, and Peter Wright. Sue Roberts and Emily 

Sabado assisted with the preparation of this report. 

ENVIRONMENTAL SETTING

The Wind River and Bighorn River compose a 

large part of the YRB in Wyoming. The drainage area 

for the Wind River Basin covers about 20,300 km2

before the river changes name to the Bighorn River at 

the “Wedding of the Waters.” The drainage area for the 

Bighorn River Basin above Bighorn Lake at Kane, 

Wyo. is the largest of the three basins in the synoptic 

study and covers about 40,800 km2

, which includes the 

area drained by the Wind River. The Shoshone River 

Basin at Kane, Wyo., also part of the Bighorn River 

Basin above Bighorn Lake, drains an additional 

7,740 km2. Goose Creek is tributary to the Tongue 

River in the eastern drainage area of the YRB. The 

Goose Creek Basin is a small basin and covers about 

1,060 km2 at Acme, Wyo. 

The Wind River, Bighorn River, and Goose Creek 

Basins all have the same general physiography of high 

mountains and lowland basins. The Bighorn River 

Basin and parts of the Wind River and Goose Creek 

Basins are part of the Middle Rocky Mountains province. Lowland basins of the Wind River Basin are part 

of the Wyoming Basin province, and lowlands of the 

Goose Creek Basin are part of the Unglaciated Missouri Plateau section (Zelt and others, 1999). All three 

basins are geologically similar, with Precambrian rocks 

at the center of the high mountains that are flanked by 

Paleozoic and Mesozoic sedimentary rocks. Tertiary 

rocks, partially overlain by Quaternary alluvium, are 

typical of the lowland basins. In the Wind and Bighorn 

River Basins, Eocene rocks associated with the Absaroka volcanic field also are present (Zelt and others, 

1999). 
6 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

Cold winters and warm summers characterize the 

climates of the lowland basins (Western Regional Climate Center, 2002). All three basins have a similar 

range of minimum and maximum mean monthly temperatures during the year (table 1). Annual precipitation varies among the basins. Annual precipitation is 

about 180 millimeters in Greybull, Wyo., about 

220 millimeters in Riverton, Wyo., and about 380 millimeters in Sheridan, Wyo. Maximum temperatures 

decrease and annual precipitation increases with 

increasing elevation in all three basins. 

The distribution of the land cover for the basins 

was determined using the National Land Cover Data 

(NLCD), a 30-meter resolution, raster-based dataset. 

Details of the NLCD land-cover classification process 

are discussed in Vogelmann, Sohl, Campbell, and 

Shaw (1998) and Vogelmann, Sohl, and Howard 

(1998). The land-cover classifications in the synopticstudy basins included: water (open water, snow/ice), 

developed (residential, commercial, industrial, transportation), barren (bare rock/sand/clay, quarries/strip 

mines/pits, transitional), forested upland (deciduous, 

evergreen and mixed forest), shrubland, herbaceous 

upland natural/semi-natural vegetation (grasslands/

herbaceous), herbaceous planted/cultivated (pasture/

hay, row crops, small grains, fallow, urban and recreation grasses), and wetland (woody wetlands, emergent 

herbaceous wetlands).

The distributions of land cover in the Wind and 

Bighorn River Basins are similar; the Goose Creek 

Basin has a higher percentage of forested upland and 

less shrubland (fig. 2). Land cover in the Wind River 

Basin includes: shrubland (62 percent), herbaceous 

upland natural/semi-natural vegetation (21 percent), 

forested upland (10 percent), and herbaceous planted/

cultivated (4 percent). Water, developed, barren, and 

wetland land covers each overlie one percent or less of 

the area in the Wind River Basin. Land cover in the 

Bighorn River Basin includes: shrubland (52 percent), 

herbaceous upland natural/semi-natural vegetation 

(27 percent), forested upland (15 percent), and herbaceous planted/cultivated (4 percent). Water, developed, barren, and wetland land covers each overlie less 

than one percent of the area in the Bighorn River Basin. 

Land cover in the Goose Creek Basin includes: forested upland (41 percent), herbaceous upland natural/

semi-natural vegetation (35 percent), herbaceous 

planted/cultivated (15 percent), shrubland (5 percent), 

and wetland (2 percent). Water, developed, and barren 

land covers each overlie one percent or less of the area 

in the Goose Creek Basin.

Table 1. Minimum and maximum mean monthly air temperatures for climate stations in the Wind River, 

Bighorn River, and Goose Creek Basins, Wyoming. 

Climate station Basin

Mean monthly

Period of 

record

 Temperature 

minimum 

(month)

Temperature 

maximum 

(month)

Riverton, Wyo. Wind River -10oC (January) 21oC (July) 1918-2000

Greybull, Wyo. Bighorn River -8oC (January) 22oC (July) 1951-2000

Sheridan, Wyo. Goose Creek -6oC (January) 21oC (July) 1948-2000
SAMPLING SITES AND METHODS 7

Figure 2. Relative distribution of land cover in the Wind River, Bighorn River, and Goose Creek Basins, Wyoming.

SAMPLING SITES AND METHODS

Sampling sites were selected based on land cover, 

site access, presence of an existing or historical stream 

gage, and input from local agencies. Twenty-three sites 

were sampled along the Wind River, Little Wind River, 

and selected tributaries (fig. 3), 53 sites were sampled 

along the Bighorn River, Shoshone River, and selected 

tributaries (fig. 4), and 24 sites were sampled along Big 

Goose Creek, Little Goose Creek, Goose Creek, and 

selected tributaries (fig. 5). Map numbers, USGS site 

numbers, and site names for sites in all three basins are 

listed in table 2. 

Methods used during field measurements, sample 

collection, and fecal-indicator-bacteria sample processing are described in the following sections. Methods 

used during data analysis, including comparisons to 

water-quality criteria, land-cover classification for sites, 

and statistical analysis, and microbial source-tracking 

methods also are described. 

Field Measurements and Sample Collection 

Measurements of standard NAWQA field waterquality constituents were made during the samplecollection visits of the synoptic study. Standard methods for sample collection and field measurements of 

water-quality constituents are described in the National 

Field Manual for the Collection of Water-Quality Data 

(U.S. Geological Survey, 1997 to 2002). Streamflow 

was measured using the methods described in Rantz and 

others (1982) during the sample-collection visit when a 

stream gage did not exist. Streamflow for sites with 

gages were either measured or computed from stagestreamflow ratings. Most of the streams for this synoptic study were wadeable, and samples were collected 

using a DH-81 sampler and equal-width-integrating 

sampling techniques in order to cross-sectionally composite the samples. For non-wadeable streams, samples 

were collected with a D-95 sampler, and multiplevertical sampling techniques were used if an acceptable 

bridge or cableway existed. Samples from a few sites 

were collected using a hand-dip method because the 

sites either were too shallow for a sampler or did not 

have an acceptable bridge or cableway. 

Air temperature, water temperature, and dissolved 

oxygen were measured on-site at the time of sample collection. Cross-sectionally composited samples were 

used for measurements of pH, specific conductance, turbidity, and filtered alkalinity. Specific conductance and 

pH were determined using electronic meters. Turbidity 

was measured using a Hach 2100P portable field turbidimeter, sensitive to 1,000 NTU (nephelometric turbid-
8 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

ity units). Alkalinity samples were filtered through a 

0.45-micrometer plate filter and titrated with an 

inflection-point method using incremental additions of 

sulfuric acid. Two deviations from standard procedures 

for pH, specific conductance, turbidity, and filtered 

alkalinity were necessary because of the scale of the 

synoptic study: 1) samples were prepared and analyzed 

for these constituents at a central field laboratory as 

quickly as possible after collection rather than on site, 

and 2) constituents were not determined in triplicate 

because sample volumes were limited. Suspendedsediment samples were cross-sectionally composited 

and sent to the sediment laboratory at the USGS Montana District office for analysis (Lambing and Dodge, 

1993). 

Sterile conditions are required for the collection, 

preservation, and storage of samples for fecal-indicator 

bacteria. Details on methods used for agar preparation 

and fecal-indicator-bacteria processing are described in 

Myers and Sylvester (1997) and U.S. Environmental 

Protection Agency (2000). To help minimize analytical 

variability, all samples were processed using the same 

equipment and same person at a central field laboratory. 

Multiple aliquots of stream water (generally 3 mL (milliliters), 10 mL, 30 mL, and 100 mL) were processed 

through the membrane filters to increase the likelihood 

of an ideal enumeration. Enumeration methods are 

described in Myers and Sylvester (1997). Fecalindicator-bacteria concentrations are listed as ‘E’ for 

estimated, with a qualifier ‘k’ when counts were outside 

the ideal range of 20 to 60 colonies for fecal coliform or 

20 to 80 colonies for E. coli. A few concentrations are 

listed as ‘E’ for estimated, without the non-ideal colony 

count qualification because only a partial plate was 

readable. Waters with large sediment concentrations or 

poorly formed colonies can result in a plate that is 

unreadable or only partially readable. E. coli concentrations are not listed for three sites because the entire plate 

was unreadable and an estimate could not be made. 

Quality-control samples, including blanks and replicates, were collected during the synoptic study. Sampling equipment blanks, membrane-filtration equipment 

blanks, and membrane-filtration procedure blanks were 

processed with sterile water to determine if contamination occurred during the sample collection or processing. Sampling equipment blanks were processed for 

each sampler bottle and nozzle. Membrane-filtration 

equipment blanks were processed for every sample 

before sample aliquots were processed to assure that the 

filtration equipment and buffer water were sterile. 

Membrane-filtration procedure blanks were processed 

after the filtration process to assure that the rinsing procedures used during sample processing were adequate. 

Generally, procedure blanks are processed at least every 

fourth sample (Francy and others, 2000). Twenty-five 

percent of samples were processed with the procedure 

blanks, although not necessarily after every fourth sample due to the large number of samples and limitations 

on incubator space at a given time. 

Replicate samples were analyzed to determine variability of fecal-indicator-bacteria concentrations resulting from sample processing procedures. The equation 

used for determining the relative percent difference 

(RPD) between the environmental sample and the replicate samples is:

Replicate samples were processed from the same bottle 

as the environmental sample.

Data Analysis

Data in this report are compared to water-quality 

criteria for assessing relative magnitude of fecalindicator-bacteria concentrations. During 2000, the 

State of Wyoming used fecal-coliform water-quality 

criteria for assessing sanitary water quality based on the 

criteria recommended in 1976 by the U.S. Environmental Protection Agency (EPA) (U.S. Environmental Protection Agency, 1976). The State of Wyoming criteria 

for fecal coliform for a water body are not a single number but are based on multiple samples, the class of water, 

time of year, and location relative to sewage treatment 

outfalls (Wyoming Department of Environmental Quality, 1990). Historically, EPA studies determined that 

statistically significant swimming-associated gastrointestinal illness may occur when concentrations of 

fecal coliform are greater than 400 col/100 mL for a single sample (U.S. Environmental Protection Agency, 

1976). 

E. coli was determined to have a stronger relation to 

swimming-associated gastrointestinal illness than fecal 

coliform and, as such, was determined to be a better 

fecal-indicator bacteria for monitoring recreational 

RPD = sample1-sample2

sample1 sample2 +

2 --------------------------------------------------    

--------------------------------------------------------

   

 

x 100
SAMPLING SITES AND METHODS 9

Figure 3. Location of sampling sites in the Wind River Basin, Wyoming, July 2000.
10 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

Figure 4. Location of sampling sites in the Bighorn River Basin, Wyoming, July 2000.
SAMPLING SITES AND METHODS 11

Figure 5. Location of sampling sites in the Goose Creek Basin, Wyoming, June 2000.
12 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA Table 2. Site information for sampling sites in the Wind River, Bighorn River, and Goose Creek Basins, Wyoming, June-July 2000 Site map number (figs. 4, 5, 6) USGS Site No. Site name Site map number (figs. 4, 5, 6) USGS Site No. 

1 06218500 Wind River near Dubois, Wyo. 51 06274220 Nowood River at Man2 06220800 Wind River above Red Creek, near Dubois, Wyo. 52 06274300 Bighorn River at Basin3 431950109085501 Crow Creek near confluence with Wind River, near Lenore, 

Wyo.

53 440617108572801 Wood River near mout

4 06225500 Wind River near Crowheart, Wyo. 54 06276500 Greybull River at Mee5 06227600 Wind River near Kinnear, Wyo. 55 442328108350101 Greybull River near Pa

Wyo. 

6 06228000 Wind River at Riverton, Wyo. 56 442514108293700 Greybull River at Aven7 06228350 South Fork of the Little Wind River above Washakie 

Reservoir, near Fort Washakie, Wyo. 

57 442815108032600 Greybull River at mou

8 430211108463201 Little Wind River in Ethete, Wyo. 58 442919108024901 Bighorn River at Grey9 06231000 Little Wind River above Arapahoe, Wyo. 59 443055108252101 Dry Creek near Emble

10 06231600 (Middle) Popo Agie River below the Sinks, near Lander, Wyo. 60 06278000 Dry Creek at Greybull11 425054108423401 Middle Popo Agie River in Lander, Wyo. 61 443246107295701 Shell Creek above She

Wyo. 

12 425250108433201 North Fork Popo Agie River near mouth, near Lander, Wyo. 62 06278400 Granite Creek near Sh13 06232600 Popo Agie River at Hudson Siding, near Lander, Wyo. 63 06278500 Shell Creek near Shell14 06233500 Little Popo Agie River at Hudson, Wyo. 64 443223107453901 Trapper Creek near mo15 06233900 Popo Agie River near Arapahoe, Wyo. 65 443229107503501 Beaver Creek near mo16 06235500 Little Wind River near Riverton, Wyo. 66 06279090 Shell Creek near Grey17 06236100 Wind River above Boysen Reservoir, near Shoshoni, Wyo. 67 06279440 Crystal Creek near Gre18 06244500 Fivemile Creek above Wyoming Canal, near Pavillion, Wyo. 68 06279500 Bighorn River at Kane19 06253000 Fivemile Creek near Shoshoni, Wyo. 69 06280300 South Fork Shoshone 20 06255500 Poison Creek near Shoshoni, Wyo. 70 06281700 Shoshone River above 21 06256650 Badwater Creek at Lysite, Wyo. 71 06284500 Bitter Creek near Garla22 06258000 Muddy Creek near Shoshoni, Wyo. 72 444524108331801 Whistle Creek near By23 06259000 Wind River below Boysen Reservoir, Wyo. 73 06285100 Shoshone River near L24 433520108125501 Bighorn River at Wedding of the Waters, near Thermopolis, 

Wyo.

74 444932108254201 Foster Gulch near Lov

25 433612108115001 Bighorn River below Buffalo Creek, near Thermopolis, Wyo. 75 06285500 Sage Creek near Love26 06259500 Bighorn River at Thermopolis, Wyo. 76 06286200 Shoshone River at Kan27 433941108114501 Bighorn River at White Sulfur Springs, near Thermopolis, 

Wyo. 

77 443559107122501 East Fork Big Goose C

Big Horn, Wyo. 
SAMPLING SITES AND METHODS 13

28 06260000 South Fork Owl Creek near Anchor, Wyo. 78 06301500 West Fork Big Goose 29 434207108281701 Owl Creek at Middleton School, near Hamilton Dome, Wyo. 79 444319107085201 Big Goose Creek belo30 06264500 Owl Creek near Lucerne, Wyo. 80 443654107110101 Rapid Creek on Forest 

Wyo.

31 06264700 Bighorn River at Lucerne, Wyo. 81 06302200 Big Goose Creek abov32 433653107504501 Kirby Creek on Kirby Creek Road, near Thermopolis, Wyo. 82 444503107061601 Big Goose Creek at Co33 434227107541501 Kirby Creek above Lake Creek, near Kirby, Wyo. 83 444550107042601 Big Goose Creek belo34 434331107565701 Kirby Creek below Lake Creek, near Kirby, Wyo. 84 444637107014701 Big Goose Creek on H35 06265337 Cottonwood Creek at High Island Ranch, near Hamilton 

Dome, Wyo.

85 444631107010901 Big Goose Creek three 

36 435213108080701 Bighorn River at Hanover Flume, near Winchester, Wyo. 86 444803106574701 Big Goose Creek in K37 06266450 Gooseberry Creek at State Highway 431, near Grass Creek, 

Wyo.

87 443638107070201 Tepee Creek near cam

38 06267000 Gooseberry Creek at Neiber, Wyo. 88 06303700 Little Goose Creek abo39 06267050 Bighorn River at Neiber, Wyo. 89 443900107002201 Little Goose Creek at 

Horn, Wyo.

40 06267420 Nowater Creek four miles south of Worland, Wyo. 90 444014106593401 Little Goose Creek on 

Wyo. 

41 440044107584301 Fifteenmile Creek at Worland, Wyo. 91 444101106591501 Little Goose Creek on 

Wyo. 

42 440045107581401 Sage Creek at mouth, near Worland, Wyo. 92 444246106572801 Little Goose Creek at 

Wyo.

43 06268600 Bighorn River at Worland, Wyo. 93 444415106565001 Little Goose Creek at 

Park Village, near She

44 06268640 Slick Creek near Worland, Wyo. 94 444634106565401 Little Goose Creek be

Sheridan, Wyo.

45 441138107545501 Bighorn River near Rairden, Wyo. 95 06304500 Little Goose Creek at 46 06269500 Bighorn River at Manderson, Wyo. 96 444848106573701 Goose Creek at 11th S47 06270000 Nowood River near Tensleep, Wyo. 97 444916107013401 Soldier Creek on Coun48 440457107183500 Tensleep Creek above Leigh Creek, near Tensleep, Wyo. 98 444911106574601 Soldier Creek near mo49 440959107410301 Nowood River near Big Horn County line, near Hyattville, 

Wyo.

99 06305500 Goose Creek below Sh

50 06273500 Paint Rock Creek near mouth, below Hyattville, Wyo. 100 06305700 Goose Creek near Acm

Table 2. Site information for sampling sites in the Wind River, Bighorn River, and Goose Creek Basins, Wyoming, June-July 2000--Con

Site map 

number 

(figs. 4, 

5, 6) USGS Site No. Site name

Site map 

number 

(figs. 4, 

5, 6) USGS Site No. 
14 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

waters (Dufour, 1984; U.S. Environmental Protection 

Agency, 1986). The EPA recommends four different 

limits for E. coli concentrations for a single sample, 

depending on the degree of exposure with the source 

waters. The recommended limits for E. coli for a single 

sample defined in the EPA study are: 235 col/100 mL 

for designated beach areas, 298 col/100 mL for moderate use, full-body recreational contact, 406 col/100 mL 

for light use, full-body recreational contact, and 

576 col/100 mL for infrequent use, full-body recreational contact. The E. coli limit for designated beach 

areas was not used in this report because none of the 

synoptic-study sites were at designated beaches. 

In the assessment of fecal-indicator bacteria by 

basin, the population densities of humans and livestock, 

which are sources for fecal contamination, were determined. Human population densities for basins were 

estimated from the 2000 county census data (U.S. Census Bureau, 2002). Livestock population densities 

(including cattle, cows, milk cows, and breeding sheep) 

were estimated from the Wyoming Agricultural Statistics Service county data for 2000 (Wyoming Agricultural Statistics Service, 2002). Fremont County data 

were used to estimate the Wind River Basin, and Hot 

Springs, Washakie, Bighorn and Park Counties data 

were used to estimate the Bighorn River Basin. The 

Goose Creek Basin is about 16 percent of the area of 

Sheridan County. Human population for the Goose 

Creek Basin was estimated by using populations for 

individual towns in the Goose Creek Basin and about 

16 percent of the rural population of the basin. For livestock, 16 percent of the county livestock populations 

were assumed to be in the Goose Creek Basin. 

For the purposes of data analysis in this report, 

land-cover classifications were combined or renamed 

and a single land-cover attribute was assigned to each 

sampling site. The forested upland land-cover classification is termed “forested,” shrubland and herbaceous 

upland natural/semi-natural vegetation land-cover classifications were combined and are termed “rangeland,” 

the herbaceous planted/cultivated land-cover classification is termed “agricultural,” and the developed landcover classification is termed “urban.” The urban and 

recreational grasses, which are classified in the NLCD 

as herbaceous planted/cultivated land cover, comprised 

1 percent or less of the agricultural classification in the 

Wind and Bighorn River Basins and about 2 percent in 

the Goose Creek Basin. Although urban and recreational grasses are not actually agricultural cover, they 

were not considered to be a significant enough component of the land cover to warrant a separate classification. 

Land cover for the drainage area upstream from 

most sampling sites included more than a single landcover classification. To determine the land-cover designation for each sampling site, a 500-meter buffer was 

established around each point using a geographic information system. The land cover with the highest percentage of area within the buffer and upstream from the site 

was assigned as the land-cover attribute for the sampling 

site. It is important to note that land-cover areas cannot 

be completely separated, and adjacent upstream land 

covers may affect the water quality of a downstream 

reach.

Data in this report are summarized using boxplots 

and nonparametric statistics. For boxplots, the lower 

and upper edges of the box indicate the 25th and 

75th percentiles, respectively. The median is a line 

within the box, and whiskers extend to the 10th and 

90th percentiles. Values outside the 10th and 90th percentiles are shown as individual points. Nonparametric 

statistical techniques were used to test for correlations 

and statistical differences between data sets because the 

fecal-indicator-bacteria data were not normally distributed. Spearman’s correlation coefficient (Spearman’s 

Rho) was used to measure the strength and direction of 

the relation between variables (Helsel and Hirsch, 

1995). The coefficient is determined using linear correlation of ranks of the data values instead of actual data 

values and is resistant to the effects of outliers. Spearman’s Rho values range between –1 and +1; a negative 

value indicates an inverse relation between the data 

ranks. Two tests were used for testing statistical differences between data sets. The Wilcoxon rank-sum test 

was used to compare two groups, and the KruskalWallis test was used for more than two groups. For both 

tests, data ranks are used rather than actual data values 

to reduce the effect of outliers. In the most general form, 

the Wilcoxon rank-sum test determines whether the two 

distributions of ranked data are similar. Likewise, the 

Kruskal-Wallis test determines whether three or more 

groups of ranked data have similar distributions or at 

least one group differs in its distribution (Helsel and 

Hirsch, 1995). Statistical significance was determined 

using a 95 percent confidence level (alpha=0.05) for 

both tests. 
SYNOPTIC-STUDY RESULTS 15

Microbial Source Tracking 

A microbial source-tracking method using discriminant analysis of ribotype patterns, performed at the 

University of Missouri in Columbia, Mo. (Carson and 

others, 2001), was selected to be tested at two sites from 

the synoptic-study area where fecal-indicator bacteria 

were known to exist in the basins. Raw water samples 

were collected from two sites and shipped on ice overnight to the University of Missouri. At the time of this 

study, the method was still under development, and the 

results of this sampling are considered experimental 

data. In general terms, individual colonies are isolated 

from the water samples and cultured. DNA is extracted 

from each isolate culture and the concentration is measured. The DNA is blotted from gels onto nylon membranes. Ribotype patterns are captured for computer 

analysis by placement on a flatbed scanner, and patterns 

of bands are converted to a line diagram and DNAfragment sizes are assigned. Discriminant analysis is 

performed to compare the presence or absence and number of bands in a given segment. Patterns are compared 

against a library of patterns for known isolates. A 

detailed description of the method steps, including the 

E. coli culturing, DNA extraction, southern blot analysis, probe preparation, hybridization, and the statistical 

analysis, is contained in Parveen and others (1999) and 

Carson and others (2001). 

The discriminant analysis technique used to determine sources can analyze patterns as: 1) human or nonhuman, or as 2) human and individual animal host 

classes. The average rate of correct classification 

reported for the method for known human and nonhuman isolates was 97 percent by Carson and others 

(2001). Rates of correct classification for up to eight 

individual host classes for known-host sources ranged 

between 49 and 96 percent (Carson and others, 2001). 

For this report, isolates were classified as human and 

nonhuman because of the higher average rate of correct 

classification. The method testing and average rate of 

correct classification was performed with known 

sources for isolates, whereas the synoptic-study samples 

had unknown sources for isolates. 

SYNOPTIC-STUDY RESULTS

The synoptic sampling of 100 sites in the Wind 

River, Bighorn River, and Goose Creek Basins was conducted during June and July 2000. Fecal-indicatorbacteria concentrations and measurements of other 

water-quality constituents are presented in table 3. The 

lowest concentration of fecal coliform for 100 samples 

was 2 col/100 mL for the (Middle) Popo Agie River 

below the Sinks, near Lander, Wyo. (site 10) and the 

Wind River below Boysen Reservoir, Wyo. (site 23) in 

the Wind River Basin. The highest concentration was 

3,000 col/100 mL in a sample from Foster Gulch near 

Lovell, Wyo. (site 74) in the Bighorn River Basin. The 

lowest concentration of E. coli for 97 samples was 

1 col/100 mL for the (Middle) Popo Agie River below 

the Sinks, near Lander, Wyo. (site 10) and the Wind 

River below Boysen Reservoir, Wyo. (site 23). The 

highest E. coli concentration was 2,800 col/100 mL in a 

sample from Foster Gulch near Lovell, Wyo. (site 74). 

Sampling Conditions 

Because each synoptic sample represents only one 

point in time for each site, it is important to put the synoptic sampling conditions in some context relative to the 

hydrologic regime and historical data. In an attempt to 

reduce the hydrologic variability within the study, samples were collected at the 100 sites during a short period 

of time, between June 27, 2000 and July 20, 2000. The 

June-July time period was selected because human 

exposure to pathogens through recreational contact with 

water is highest during the summer months. 

Hydrographs for the water year and the streamflow 

at the time of sampling for the terminal sites for the 

mainstem stream in each of the basins are presented in 

figure 6. The terminal sites, which represent the lowest 

site sampled on the mainstem streams are the Wind 

River above Boysen Reservoir, near Shoshoni, Wyo. 

(site 17), Bighorn River at Kane, Wyo. (site 68), and 

Goose Creek near Acme, Wyo. (site 100). The 

hydrograph for the Wind River above Boysen Reservoir, near Shoshoni, Wyo. (site 17) is shown rather than 

the hydrograph for the site below the reservoir (site 23) 

because of the regulated conditions directly below the 

reservoir. The synoptic sampling was conducted after 

snowmelt runoff that occurred in late May and early 

June in each basin had subsided. In the plains, some of 

the smaller tributaries that experience an earlier runoff 

were at or near low-flow conditions. Streamflows in the 

basins may be affected by irrigation diversions, return 

flows, or reservoirs upstream that alter the natural 

hydrologic regime.
16 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

Table 3. Streamflow, physical-characteristics, and fecal-indicator-bacteria results for the Wind 

[NTU, nephelometric turbidity units; mm of Hg, millimeters of mercury; mg/L, milligrams per liter; μS/cm, microsiemens 

 >. greater than; E, estimated value; k, count outside 

Site map 

number 

(figs. 3, 4, 5; 

tab. 2)

Date 

sampled

Time 

sampled

Streamflow, 

(cubic feet 

per second)

Turbidity 

(NTU)

Barometric 

pressure 

(mm of Hg)

Oxygen, 

dissolved 

(mg/L)

Oxygen, 

dissolved 

(percent 

saturation)

pH 

(standard 

units)

Wind River

1 07-11-00 0830 155 6.9 591 9.6 111 7.6

2 07-11-00 0900 842 7.2 606 8.7 103 8.3

3 07-11-00 0900 7.1 5.3 619 8.4 103 8.2

4 07-11-00 1330 1650 2.7 597 8.4 112 8.7

5 07-11-00 1430 434 2.5 632 11.8 159 9.1

6 07-11-00 1615 21 3.2 638 7.8 116 8.9

7 07-12-00 0930 169 1.2 610 8.1 96 7.8

8 07-12-00 0900 18 2.2 632 10.1 128 8.3

9 07-12-00 1300 30 6.5 639 -- -- 8.6

10 07-10-00 1600 151 4.1 610 11.0 140 7.5

11 07-11-00 1630 7.7 1.2 628 6.4 98 8.6

12 07-11-00 1445 52 2.2 629 7.0 100 8.6

13 07-11-00 1630 108 3.5 632 10.4 149 8.8

14 07-12-00 0835 22 8.6 639 6.3 80 8.0

15 07-12-00 1300 106 4.3 639 6.8 97 8.5

16 07-12-00 1055 162 4.0 643 11.8 161 8.3

17 07-12-00 1620 256 8.5 642 7.2 106 8.6

18 07-13-00 0725 .03 <1.0 629 7.8 -- 7.6

19 07-12-00 1500 E279 -- 644 -- -- 8.6

20 07-13-00 1045 .19 3.1 645 9.0 128 8.2

21 07-12-00 1330 .96 27 635 5.9 95 8.2

22 07-12-00 1700 45 160 644 7.5 109 8.6

23 07-13-00 1500 1350 3.9 645 8.5 110 8.5

Bighorn River

24 07-14-00 0900 E1320 4.8 653 10.3 128 8.3

25 07-14-00 1030 1670 3.4 -- -- -- 8.5

26 07-17-00 1300 1430 5.6 653 13.3 175 8.9

27 07-14-00 1300 E1430 4.0 654 8.2 -- 8.7

28 07-14-00 0940 33 3.4 606 8.3 104 8.1

29 07-14-00 1340 .81 3.1 637 7.1 102 8.6

30 07-13-00 1345 5.4 6.6 655 10.4 145 8.7
SYNOPTIC-STUDY RESULTS 17

River, Bighorn River, and Goose Creek Basins, Wyoming, June-July 2000

per centimeter at 25 degrees Celsius; deg C, degrees Celsius; col/100 mL, colonies per 100 milliliters; <, less than;

 acceptable range (non-ideal); --, missing value]

Specific 

conductance 

(μS/cm)

Temperature, 

air 

(deg C)

Temperature, 

water 

(deg C)

Alkalinity, 

dissolved 

(mg/L as 

CaCO3)

Bicarbonate, 

dissolved 

(mg/L as 

HCO3)

Carbonate, 

dissolved 

(mg/L as 

CO3

-2)

Fecal 

coliform 

(col/100 mL)

Escherichia 

coli, 

(col/100 ml)

Sediment, 

suspended 

(mg/L)

Basin

160 11.5 10.5 72 88 -- 160 130 14

194 25.0 12.5 81 98 -- 130 E160k 17

293 19.0 15.0 133 162 -- 170 E94k 4

140 26.0 17.0 54 66 1 E20k E10k 15

211 33.0 20.5 77 81 6 E33k E23k 16

529 28.5 26.0 150 161 11 38 E30k 6

32 26.5 13.0 13 16 -- E23k E6k 4

454 21.0 17.5 104 127 -- 26 E20k 4

895 35.0 23.5 176 201 7 63 E67k 14

43 22.0 16.0 18 22 -- E2k E1k 3

478 30.0 27.0 151 177 4 340 450 14

362 32.5 23.0 111 134 -- 190 E180k 3

604 32.5 23.5 158 177 7 150 E100k 13

1180 32.0 18.0 217 264 -- 240 E130k 70

812 34.0 24.0 174 203 5 32 E46k 27

898 32.0 22.0 179 205 6 E50k E32k 52

744 35.0 26.0 182 213 5 E48k E10k 28

4230 -- -- 184 225 -- 37 33 22

685 35.0 -- 156 185 2 300 E400k 241

6160 35.0 23.5 275 336 -- 2000 2300 54

4930 34.0 29.5 397 484 -- 47 E62k 70

784 35.0 25.5 142 165 4 800 >200 390

595 37.0 19.5 138 162 3 E2k E1k 5

Basin

616 23.5 18.0 158 178 7 E10k E10k --

615 -- -- 136 164 -- E12k E15k 8

617 30.0 21.0 143 164 5 32 E14k 7

634 -- -- 148 167 6 E16k E25k --

100 31.0 15.0 46 57 -- 240 140 6

2070 33.5 24.0 346 407 8 340 E300 24

1540 -- 24.0 236 274 7 1500 620 86
18 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

Table 3. Streamflow, physical-characteristics, and fecal-indicator-bacteria results for the Wind 

Site map 

number 

(figs. 3, 4, 5; 

tab. 2)

Date 

sampled

Time 

sampled

Streamflow, 

(cubic feet 

per second)

Turbidity 

(NTU)

Barometric 

pressure 

(mm of Hg)

Oxygen, 

dissolved 

(mg/L)

Oxygen, 

dissolved 

(percent 

saturation)

pH 

(standard 

units)

Bighorn River

31 07-14-00 1650 1260 2.0 -- -- -- 8.9

32 07-13-00 1100 .06 22 642 9.1 124 8.6

33 07-13-00 1200 .01 21 -- 9.0 -- 8.7

34 07-13-00 1230 .68 13 652 6.2 89 8.7

35 07-14-00 1115 E.48 5.0 624 11.8 -- 9.7

36 07-17-00 1445 742 12 657 8.4 107 8.5

37 07-19-00 1600 .90 3.6 620 7.7 121 8.5

38 07-15-00 0830 .55 5.2 655 -- -- 8.2

39 07-16-00 1445 841 12 656 9.3 131 8.7

40 07-15-00 0930 32 66 657 9.0 114 8.3

41 07-16-00 1700 13 88 -- 8.1 -- 8.6

42 07-17-00 0900 32 83 657 -- -- 8.0

43 07-17-00 1030 267 140 660 -- -- 8.2

44 07-17-00 1000 27 120 659 8.6 107 8.2

45 07-17-00 1300 471 310 663 7.0 89 8.4

46 07-18-00 0850 608 440 665 8.0 101 8.2

47 07-17-00 1200 106 6.2 649 8.9 112 8.4

48 07-17-00 1000 52 1.1 627 8.3 99 7.6

49 07-17-00 1345 75 14 656 6.6 91 8.4

50 07-17-00 1445 82 8.0 656 8.5 109 8.5

51 07-17-00 1500 136 5.5 663 8.9 120 8.2

52 07-18-00 1150 865 >1000 666 8.2 106 8.2

53 07-19-00 1030 98 3.2 613 9.0 105 8.2

54 07-19-00 1210 638 22 620 8.5 110 8.4

55 07-19-00 1500 582 62 653 8.2 97 8.3

56 07-19-00 1645 85 84 652 7.3 96 8.6

57 07-19-00 1000 112 >1000 669 7.6 94 8.2

58 07-18-00 1515 980 260 663 9.5 126 8.3

59 07-19-00 1445 22 190 653 7.7 105 8.2

60 07-19-00 0845 34 280 671 -- -- 8.2
SYNOPTIC-STUDY RESULTS 19

River, Bighorn River, and Goose Creek basins, Wyoming, June-July 2000--Continued

Specific 

conductance 

(μS/cm)

Temperature, 

air 

(deg C)

Temperature, 

water 

(deg C)

Alkalinity, 

dissolved 

(mg/L as 

CaCO3)

Bicarbonate, 

dissolved 

(mg/L as 

HCO3)

Carbonate, 

dissolved 

(mg/L as 

CO3

-2)

Fecal 

coliform 

(col/100 mL)

Escherichia 

coli, 

(col/100 ml)

Sediment, 

suspended 

(mg/L)

Basin--Continued

663 -- 24.0 139 154 8 35 E77k 19

1100 33.0 22.0 214 255 3 E670k 680 27

3700 39.0 22.0 149 177 2 1900 1700 19

3460 -- 25.0 209 244 5 420 550 32

700 32.0 -- 166 139 31 E11k E12k 20

712 22.0 19.5 152 185 -- 130 E120k 49

3200 32.0 27.0 332 391 7 260 210 62

3400 24.0 20.0 214 262 -- 330 230 5

708 34.0 25.0 150 169 7 110 E47k 40

962 25.0 19.5 206 251 -- 1500 670 184

811 -- 27.5 163 185 6 1200 1600 423

1030 23.0 17.5 223 272 -- 770 550 289

858 27.0 18.5 182 223 -- 540 400 235

970 20.0 18.5 221 270 -- 1100 800 200

910 20.0 20.0 168 199 3 830 670 380

936 22.0 20.0 196 240 -- 1400 E1000k 440

646 23.0 18.5 112 132 2 160 E180k 13

71 24.0 14.5 34 42 -- 67 65 4

765 23.0 23.0 143 175 -- 55 49 42

591 25.0 20.0 131 159 -- 220 E200k 14

758 -- 23.0 41 50 -- 62 80 10

914 26.0 21.0 166 203 -- E1000 E670 5170

236 20.0 12.5 87 106 -- 130 120 10

318 20.0 17.5 94 115 -- 58 67 54

336 18.5 16.0 101 123 -- 150 E170k 101

392 20.0 21.0 122 139 5 580 E630k 91

860 20.0 19.0 200 244 -- E2200k E1600 609

947 19.5 22.0 189 230 -- 480 540 283

2430 26.0 22.5 230 281 -- >2000 >2000 218

1360 20.0 13.0 261 319 -- 2000 E1300 398
20 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

Table 3. Streamflow, physical-characteristics, and fecal-indicator-bacteria results for the Wind 

Site map 

number 

(figs. 3, 4, 5; 

tab. 2)

Date 

sampled

Time 

sampled

Streamflow, 

(cubic feet 

per second)

Turbidity 

(NTU)

Barometric 

pressure 

(mm of Hg)

Oxygen, 

dissolved 

(mg/L)

Oxygen, 

dissolved 

(percent 

saturation)

pH 

(standard 

units)

Bighorn River

61 07-18-00 0845 90 1.6 580 8.4 97 7.4

62 07-18-00 1000 11 9.7 589 7.8 90 8.4

63 07-18-00 1540 113 6.3 655 9.5 110 8.4

64 07-18-00 1000 8.1 2.7 652 9.1 100 8.0

65 07-18-00 1145 14 6.7 655 7.7 99 8.2

66 07-18-00 1430 27 18 667 8.1 112 8.4

67 07-19-00 0920 .59 710 666 -- -- 8.2

68 07-18-00 1400 892 150 670 8.4 114 8.3

69 07-19-00 1045 487 -- 612 9.2 107 8.1

70 07-19-00 1200 1160 -- 639 9.8 109 8.1

71 07-18-00 1000 304 320 661 8.7 100 8.3

72 07-20-00 0840 47 >1000 657 8.1 98 8.4

73 07-20-00 0800 566 810 667 7.8 92 8.3

74 07-20-00 0900 43 690 666 7.8 92 8.1

75 07-20-00 0930 210 770 669 8.3 99 8.0

76 07-20-00 0800 616 730 669 7.9 91 8.2

Goose Creek

77 06-27-00 1500 11 4.6 584 8.8 101 7.1

78 06-27-00 1030 E86 1.1 565 8.1 101 6.7

79 06-28-00 1650 72 3.0 658 8.9 102 8.0

80 06-27-00 1330 64 4.8 586 9.1 103 7.2

81 06-28-00 1730 79 5.2 656 8.1 97 7.9

82 06-28-00 1830 95 4.4 658 8.7 106 8.1

83 06-29-00 0730 112 14 656 8.1 91 7.9

84 06-29-00 0800 116 15 664 8.9 99 7.9

85 06-29-00 1010 115 12 666 9.6 109 8.1

86 06-29-00 1000 122 16 663 6.8 80 8.2

87 06-27-00 1200 3.4 3.4 590 7.8 101 --

88 06-27-00 1730 69 2.0 653 9.6 99 7.4

89 06-27-00 1700 21 3.8 666 8.9 96 7.8

90 06-28-00 0850 16 13 658 9.4 99 8.0
SYNOPTIC-STUDY RESULTS 21

River, Bighorn River, and Goose Creek basins, Wyoming, June-July 2000--Continued

Specific 

conductance 

(μS/cm)

Temperature, 

air 

(deg C)

Temperature, 

water 

(deg C)

Alkalinity, 

dissolved 

(mg/L as 

CaCO3)

Bicarbonate, 

dissolved 

(mg/L as 

HCO3)

Carbonate, 

dissolved 

(mg/L as 

CO3

-2)

Fecal 

coliform 

(col/100 mL)

Escherichia 

coli, 

(col/100 ml)

Sediment, 

suspended 

(mg/L)

Basin--Continued

35 17.5 9.5 19 23 -- 130 100 4

241 20.0 10.0 120 147 -- 1600 1200 13

188 17.5 15.0 75 92 -- 93 74 7

646 21.0 12.5 219 268 -- 170 E170k 96

659 22.0 20.0 180 219 -- E680k E400k 33

1540 29.0 24.5 217 253 6 E630k 600 80

2970 22.0 16.5 340 415 -- 200 E170k 703

1000 33.0 24.0 192 234 -- 170 E120k 211

84 23.0 12.0 33 40 -- E11k E7k 9

129 27.5 12.0 47 57 -- E9k E7k 4

617 28.0 15.5 178 218 -- 500 E500k 684

669 17.0 17.0 112 137 -- E2300k 2000 859

703 18.0 16.5 178 217 -- 1800 E1200k 676

745 26.0 16.5 194 237 -- E3000k E2800k 1030

1500 22.5 17.0 220 269 -- E2200k 2000 1030

1010 16.0 15.5 201 246 -- 2000 E1200 797

Basin

37 15.0 9.5 20 24 -- 530 580 6

18 6.0 11.5 12 14 -- 55 53 7

105 26.0 15.0 34 42 -- 23 E15k 8

24 15.0 9.0 16 20 -- 130 67 26

124 25.0 16.5 46 56 -- 380 260 9

163 26.0 17.5 54 66 -- 800 >400 9

241 19.0 13.5 69 84 -- 800 -- 23

278 20.0 14.0 75 92 -- 1100 -- 19

283 23.0 15.0 80 98 -- 670 E300 21

279 22.0 16.5 75 91 -- 560 E430k 24

38 11.0 15.5 19 23 -- 360 380 6

51 15.0 10.0 26 32 -- E10k E4k 9

112 18.0 12.5 51 62 -- 97 28 8

197 17.0 11.0 97 119 -- 100 E150k 9
22 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

Table 3. Streamflow, physical-characteristics, and fecal-indicator-bacteria results for the Wind 

Site map 

number 

(figs. 3, 4, 5; 

tab. 2)

Date 

sampled

Time 

sampled

Streamflow, 

(cubic feet 

per second)

Turbidity 

(NTU)

Barometric 

pressure 

(mm of Hg)

Oxygen, 

dissolved 

(mg/L)

Oxygen, 

dissolved 

(percent 

saturation)

pH 

(standard 

units)

Goose Creek

91 06-28-00 0850 23 4.4 664 9.8 102 8.3

92 06-28-00 1120 37 18 667 9.9 109 8.4

93 06-28-00 1300 46 16 664 9.4 109 8.2

94 06-28-00 1430 77 24 665 10.6 132 8.4

95 06-28-00 1320 77 24 670 13.3 160 8.9

96 06-29-00 1215 E224 16 667 9.5 121 8.6

97 06-29-00 1240 19 86 666 8.0 96 8.1

98 06-29-00 1440 14 -- 668 7.8 95 8.2

99 06-29-00 1400 224 -- 666 9.9 125 8.7

100 06-29-00 1300 190 18 667 11.4 142 8.6

The synoptic approach used in this study for determining the distribution of fecal-indicator bacteria has 

limitations for data interpretations owing to the variable 

nature of sources and transport processes of fecalindicator bacteria. The data from the synoptic study represent only a ‘snapshot’ in time. However, fecal 

coliform historically have been collected at selected sites 

within the Wind River Basin (2 sites), Bighorn River 

Basin (5 sites), and the Goose Creek Basin (3 sites) as 

part of other monitoring programs. Fecal-coliform concentrations for samples from the synoptic study are summarized with historical data from 1991-2000 to illustrate 

how the synoptic-study concentrations compare to historical data (fig. 7). The period of record is summarized 

for each site in table 4. 

Fecal-coliform concentrations of synoptic samples 

generally were between the 50th to 75th percentiles of the 

historical data (fig. 7). The fecal-coliform concentrations for synoptic samples on the Little Wind River near 

Riverton, Wyo. (site 16) and the Bighorn River at Lucerne, Wyo. (site 31) were below the historic medians for 

those sites. For two sites in the Bighorn River Basin, 

Bighorn River at Basin, Wyo. (site 52) and Bitter Creek 

near Garland, Wyo. (site 71), the fecal-coliform concentrations for the synoptic samples were greater than the 

75th percentile of the historical data for those sites. 

Quality-Control Samples

No colonies of fecal coliform or E. coli were 

detected in the eight equipment blanks that were processed for each sampler bottle and nozzle. No bacteria 

colonies were detected in the 200 membrane-filtration 

equipment blanks that were processed for fecal 

coliform or E. coli. No colonies were detected in 

50 procedure blanks for fecal coliform or E. coli. 

Seventeen replicate samples are reported for fecal 

coliform and six are reported for E. coli. Fewer E. coli

replicates are reported because some of the plates for 

the replicates were unreadable. The RPD for the replicate samples are listed in table 5. The mean and 

median RPD for fecal-coliform replicates (n=17) were 

about 13 percent. The mean RPD for E. coli replicates 

(n=6) was 25.4 percent, and the median RPD was 

14.5 percent. This indicates that there may be more 

variability about the E. coli replicates than the fecalcoliform replicates; however, the sample size was 

smaller for the E. coli replicates, which can increase 

apparent variability. The variability in replicate data 

explains, in part, why the E. coli concentration exceeds 

the fecal-coliform concentration in some samples. 
SYNOPTIC-STUDY RESULTS 23

River, Bighorn River, and Goose Creek basins, Wyoming, June-July 2000--Continued

Specific 

conductance 

(μS/cm)

Temperature, 

air 

(deg C)

Temperature, 

water 

(deg C)

Alkalinity, 

dissolved 

(mg/L as 

CaCO3)

Bicarbonate, 

dissolved 

(mg/L as 

HCO3)

Carbonate, 

dissolved 

(mg/L as 

CO3

-2)

Fecal 

coliform 

(col/100 mL)

Escherichia 

coli, 

(col/100 ml)

Sediment, 

suspended 

(mg/L)

Basin--Continued

251 15.0 11.0 122 149 -- 120 90 9

346 17.0 13.5 166 203 -- 280 200 20

398 22.0 15.5 187 219 -- 270 200 30

376 24.0 19.0 174 180 16 E190k 140 35

410 21.0 18.0 178 188 14 190 150 29

338 30.0 20.5 101 112 6 600 -- 23

383 29.0 17.5 121 148 -- 1500 E800 134

426 30.0 18.5 151 184 -- 1100 E700 184

353 29.0 20.0 124 140 6 380 E240 29

359 29.0 19.5 126 144 5 300 E170 30

Distribution of Fecal-Indicator Bacteria by 

Basin

Median concentrations of fecal-indicator bacteria 

varied among basins (fig. 8). The lowest median concentrations of fecal coliform (50 col/100 mL) and 

E. coli (62 col/100 mL) were for samples in the Wind 

River Basin. The highest median concentrations of 

fecal coliform (340 col/100 mL) and E. coli

(300 col/100 mL) were for samples in the Bighorn 

River Basin. For samples in the Goose Creek Basin, 

the median concentration of fecal coliform was 

330 col/100 mL, and the median concentration of 

E. coli was 200 col/100 mL. 

Results of the Kruskal-Wallis test indicate a significant difference in fecal-coliform concentrations 

(p-value =0.003) and E. coli concentrations 

(p-value =0.001) between basins at a 95 percent confidence level. A Wilcoxon rank-sum test was run 

between each pair of basins to determine which distributions were different. The fecal-coliform 

(p-value =0.35) and the E. coli (p-value =0.193) concentrations in the Bighorn River and Goose Creek 

Basins were not significantly different from each other. 

The concentrations of fecal-indicator bacteria in the 

Wind River Basin were statistically different from 

those in the Bighorn River (p-value for fecal coliform 

=0.002; p-value for E. coli =0.001) and Goose Creek 

Basins (p-value for fecal coliform =0.008; p-value for 

E. coli =0.014). Most samples in the Wind River Basin 

had fecal-indicator-bacteria concentrations that were 

less than the median concentrations in the Bighorn 

River or Goose Creek Basins (fig. 8). 

Because the synoptic samples represent the conditions at only one point in time, the reason for the lower 

concentrations in the Wind River Basin during this 

study could not be determined. In 2000, stream reaches 

in the Bighorn River and Goose Creek Basins were 

listed by the State of Wyoming for fecal-coliform 

impairments, whereas reaches in the Wind River Basin 

were not listed (Wyoming Department of Environmental Quality, 2000). The variation in fecal-indicator bacteria between basins is not directly related to the 

populations of livestock and humans in the basins. The 

population densities of humans and livestock were not 

higher in the Bighorn River Basin when compared to 

the Wind River Basin (table 6). Human and livestock 

population densities were substantially higher in the 

Goose Creek Basin than in the other two basins. The 

overall basin density does not take into account, however, the distribution of people and livestock relative to 

their actual proximity to riparian areas. 
24 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

Figure 6. Annual hydrographs and streamflows for terminal sites during 

a synoptic study in the Wind River, Bighorn River, and Goose Creek 

Basins, Wyoming, 2000.
SYNOPTIC-STUDY RESULTS 25

Figure 7. Historical and synoptic-study fecal-coliform concentrations for selected sites in the Wind 

River, Bighorn River, and Goose Creek Basins, Wyoming, 1991-2000.
26 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

Table 4. Period of record for fecal-coliform concentrations for selected sites in the Wind 

River, Bighorn River, and Goose Creek Basins, Wyoming, 1991-2000.

Site map number 

(figs. 4, 5, 6; tab. 2) Basin

Period of record

(water years)

13 Wind River 1993-2000

16 Wind River 1991-2000

31 Bighorn River 1991-2000

52 Bighorn River 1991-2000

54 Bighorn River 1996-2000

68 Bighorn River 2000

71 Bighorn River 1993-2000

81 Goose Creek 1999-2000

95 Goose Creek 1991-2000

99 Goose Creek 1991-2000

Table 5. Concentrations and relative percent difference of replicate quality-control samples of fecal-indicator 

bacteria in the Wind River, Bighorn River, and Goose Creek Basins, Wyoming, June-July 2000. 

[col/100 mL, colonies per 100 milliliters; RPD, relative percent difference; --, not applicable]

Site map 

number

(figs. 3, 4, 5; 

tab. 2)

Fecal coliform 

regular 

sample

(col/100 mL)

Fecal coliform 

replicate 

sample

(col/100 mL) RPD

Escherichia coli

regular 

sample

(col/100 mL)

Escherichia coli

replicate 

sample

(col/100 mL) RPD

6 38 41 7.6 -- -- --

8 26 30 14.3 20 10 66.7

16 50 38 27.3 32 32 0.0

18 37 30 20.9 33 28 16.4

26 32 28 13.3 -- -- --

31 35 40 13.3 -- -- --

33 1900 1600 17.1 1700 1000 51.9

38 330 360 8.7 -- -- --

52 1000 900 10.5 -- -- --

57 2200 2000 9.5 -- -- --

72 2300 2200 4.4 2000 2100 4.9

73 1800 1700 5.7 -- -- --

76 2000 1900 5.1 -- -- --

80 130 110 16.7 67 59 12.7

85 670 650 3.0 -- -- --

86 560 460 19.6 -- -- --

91 120 160 28.6 -- -- --
SYNOPTIC-STUDY RESULTS 27

Figure 8. Fecal-indicator-bacteria concentrations for the Wind River, Bighorn River, and Goose Creek Basins, 

Wyoming, June-July 2000. 

Table 6. Estimated human and livestock population densities for the Wind River, Bighorn River, and 

Goose Creek Basins, Wyoming, 2000. 

Basin

Human population density, 

in persons 

per square kilometer

Livestock population density, 

in animals 

per square kilometer

Wind River 1.8 10

Bighorn River 1.0 6.6

Goose Creek 16 25
28 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

Fecal-indicator-bacteria concentrations exceeded 

the EPA’s recommended limits for a single sample for 

recreational contact with water for a percentage of samples collected from all three basins (table 7). The Bighorn River Basin had the highest percentage of samples 

(49.1 percent) with fecal-coliform concentrations higher 

than the recommended limit of 400 col/100 mL. Concentrations of fecal coliform in the Goose Creek Basin 

exceeded the recommended limit in 37.5 percent of the 

samples. Concentrations of fecal coliform in the Wind 

River Basin exceeded the recommended limit in 8.7 percent of the samples. In this report, the EPA recommended limit of 400 col/100 mL for fecal coliform is 

used for comparison purposes, but does not necessarily 

represent a violation of the State of Wyoming waterquality criteria. 

E. coli concentrations exceeded the EPA recommended limit for a single sample for moderate use, fullbody recreational contact of 298 col/100 mL in 

50.9 percent of the samples from the Bighorn River 

Basin compared to 33.3 percent in the Goose Creek 

Basin and 13.0 percent in the Wind River Basin. In the 

Bighorn River Basin, E. coli concentrations exceeded 

the EPA recommended limit for a single sample for 

infrequent use, full-body recreational contact of 

576 col/100 mL in 37.7 percent of samples compared to 

14.3 percent in the Goose Creek Basin and 4.3 percent 

in the Wind River Basin. E. coli concentrations of the 

synoptic-study samples are compared to the EPA recommended limits, but do not represent violations of 

water-quality criteria because the E. coli limits had not 

been adopted by the State of Wyoming as of 2000. 

Wind River Basin 

The synoptic sampling of the 23 sites in the Wind 

River Basin was conducted July 10-13, 2000. Seven 

sites on the mainstem of the Wind River and 16 tributary 

sites were sampled (fig. 9). Fecal-coliform concentrations for 23 samples ranged from 2 col/100 mL for the 

(Middle) Popo Agie River below the Sinks, near Lander, 

Wyo. (site 10) and the Wind River below Boysen Reservoir, Wyo. (site 23) to 2,000 col/100 mL for Poison 

Creek near Shoshoni, Wyo. (site 20). E. coli concentrations for 23 samples ranged from 1 col/100 mL (site 10 

and site 23) to 2,300 col/100 mL (site 20) (fig. 9). 

Fecal-coliform concentrations for the seven sites on 

the mainstem of the Wind River ranged from 

2 col/100 mL below Boysen Reservoir, Wyo. (site 23) 

to 160 col/100 mL near Dubois, Wyo. (site 1). Bottom 

deposits in lakes or reservoirs can serve as a sink for 

fecal-indicator bacteria and prevent the bacteria from 

being transported in the overlying material (Geldreich, 

1970). However, the fecal-coliform concentration was 

relatively low (48 col/100 mL) in a sample from the 

Wind River above Boysen Reservoir, near Shoshoni, 

Wyo. (site 17) as well. E. coli concentrations ranged 

from 1 col/100 mL below Boysen Reservoir, Wyo. 

(site 23) to 160 col/100 mL on the Wind River above 

Red Creek, near Dubois, Wyo. (site 2).

Table 7. Fecal-indicator-bacteria concentrations exceeding the U.S. Environmental Protection Agency’s 

recommended limits for a single sample for recreational contact with water for samples in the Wind River, Bighorn 

River, and Goose Creek Basins, Wyoming, June-July 2000. 

[col/100 mL, colonies per 100 milliliters; >, greater than]

Basin

Sample size 

(n)

Fecal 

coliform/

Escherichia 

coli

Fecal coliform Escherichia coli

Percent >400 

col/100 mL

Percent >298 

col/100 mL

(Moderate use, 

full-body 

contact)

Percent >406 

col/100 mL

(Light use, 

full-body 

contact)

Percent >576 

col/100 mL

(Infrequent use, 

full-body 

contact)

Wind River 23/23 8.7 13.0 8.7 4.3

Bighorn River 53/53 49.1 50.9 45.3 37.7

Goose Creek 24/21 37.5 33.3 19.0 14.3

All samples 100/97 37.0 38.1 30.9 24.7
SYNOPTIC-STUDY RESULTS 29

Figure 9. Fecal-indicator-bacteria concentrations for samples collected in the Wind River Basin, Wyoming, July 2000.

Less than 1-30

Less than 1-30
30 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

Tributaries sampled in the Wind River Basin 

included: Crow Creek, South Fork of the Little Wind 

River, Little Wind River (3 sites), Middle Popo Agie 

River (2 sites), North Fork Popo Agie River, Little Popo 

Agie River, Popo Agie River (2 sites), Fivemile Creek 

(2 sites), Poison Creek , Badwater Creek, and Muddy 

Creek. For the 16 tributary sites, the lowest fecalcoliform concentration (2 col/100 mL ) and E. coli concentration (1 col/100 mL) occurred in a sample from the 

(Middle) Popo Agie River below the Sinks, near 

Lander, Wyo. (site 10). The highest concentration of 

fecal coli-form (2,000 col/100 mL ) and E. coli

(2,300 col/100 mL) for the tributary sites occurred in a 

sample from Poison Creek near Shoshoni, Wyo. 

(site 20). 

Sites in the Wind River Basin where concentrations 

exceeded at least one of the EPA’s recommended limits 

for a single sample for recreational contact with water 

are listed in table 8. All of the fecal coliform and E. coli

concentrations on the mainstem of the Wind River were 

below the EPA recommended limits for recreational 

contact with water. Tributary sites that had concentrations exceeding at least one of the EPA’s recommended 

limits for recreational contact with water include: Middle Popo Agie River in Lander, Wyo. (site 11), Fivemile 

Creek near Shoshoni, Wyo. (site 19), Poison Creek near 

Shoshoni, Wyo. (site 20), and Muddy Creek near Shoshoni, Wyo. (site 22). 

Bighorn River Basin 

The synoptic sampling of the 53 sites in the Bighorn River Basin was conducted July 13-20, 2000. 

Thirteen sites on the mainstem of the Bighorn River and 

40 tributary sites were sampled, including 3 sites on the 

mainstem of the Shoshone River (fig. 10). Fecalcoliform concentrations for 53 samples ranged from 

9 col/100 mL for the Shoshone River above DemarisSprings, near Cody, Wyo. (site 70) to 3,000 col/100 mL 

for Foster Gulch near Lovell, Wyo. (site 74). E. coli concentrations for 53 samples ranged from 7 col/100 mL 

(sites 69 and 70) to 2,800 col/100 mL (site 74).

Fecal-coliform concentrations for the 13 sites on 

the mainstem of the Bighorn River ranged from 10 col/

100 mL at the “Wedding of the Waters” near Thermopolis, Wyo. (site 24) to 1,400 col/100 mL at Manderson, 

Wyo. (site 46). E. coli concentrations ranged from 

10 col/100 mL at the “Wedding of the Waters” near 

Thermopolis, Wyo. (site 24) to 1,000 col/100 mL at 

Manderson, Wyo. (site 46). The fecal-coliform concentration (170 col/100 mL) and E. coli concentration 

(120 col/100 mL) were lower at the terminal site on the 

Bighorn River at Kane, Wyo. (site 68) compared to the 

mid-basin Bighorn River sites. 

Tributaries to the Bighorn River above Kane, Wyo. 

that were sampled during the synoptic study include: 

South Fork Owl Creek, Owl Creek (2 sites), Kirby 

Creek (3 sites), Cottonwood Creek, Gooseberry Creek 

(2 sites), Nowater Creek, Fifteenmile Creek, Sage 

Creek, Slick Creek, Nowood River (3 sites), Tensleep 

Creek, Paint Rock Creek, Wood River, Greybull River 

(4 sites), Dry Creek (2 sites), Shell Creek (3 sites), 

Granite Creek, Trapper Creek, Beaver Creek, and Crystal Creek. For these 32 tributary sites, the lowest concentrations of fecal coliform (11 col/100 mL) and E. coli

(12 col/100 mL) were from the site on Cottonwood 

Creek at High Island Ranch near Hamilton Dome, Wyo. 

(site 35). The highest concentration of fecal coliform 

Table 8. Sites where sample concentrations of fecal-indicator bacteria exceeded the U.S. Environmental Protection 

Agency’s recommended limits for a single sample for recreational contact with water in the Wind River Basin, 

Wyoming, July 2000. 

[col/100 mL, colonies per 100 milliliters; >, greater than]

Fecal coliform Escherichia coli

>400 col/100 mL

>298 col/100 mL

(Moderate use,

full-body contact)

>406 col/100 mL

(Light use,

full-body contact)

>576 col/100 mL

(Infrequent use, 

full-body contact)

Poison Creek (site 20) Fivemile Creek (site 19) Middle Popo Agie River 

(site 11)

Poison Creek (site 20)

Muddy Creek (site 22)
SYNOPTIC-STUDY RESULTS 31

Figure 10. Fecal-indicator-bacteria concentrations for samples collected in the Bighorn River Basin Wyoming, July 2000.

Less than 1-30

Less than 1-30
32 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

(2,200 col/100 mL) was in a sample from the Greybull 

River at its mouth at Greybull, Wyo. (site 57). A fecalcoliform concentration greater than 2,000 col/100 mL 

and the highest concentration of E. coli (greater than 

2,000 col/100 mL) were in a sample from Dry Creek 

near Emblem, Wyo. (site 59).

Eight of the tributary sites in the Bighorn River 

Basin were in the Shoshone River Basin above Bighorn 

Lake. Tributaries sampled included: the South Fork 

Shoshone River, Shoshone River (3 sites), Bitter Creek, 

Whistle Creek, Foster Gulch, and Sage Creek. For these 

eight sites, the lowest concentrations of fecal coliform 

(9 col/100 mL) and E. coli (7 col/100 mL) were in a sample from the Shoshone River above Demaris Springs, 

near Cody, Wyo. (site 70). The sample from South Fork 

Shoshone River near Valley, Wyo. (site 69) also had an 

E. coli concentration of 7 col/100 mL. The highest concentrations of fecal coliform (3,000 col/100 mL) and 

E. coli (2,800 col/100 mL) in the Shoshone River Basin 

were in a sample from Foster Gulch near Lovell, Wyo. 

(site 74).

Sites in the Bighorn River Basin where concentrations exceeded at least one of the EPA’s recommended 

limits for a single sample for recreational contact with 

water are listed in table 9. Concentrations of fecal 

coliform and E. coli exceeded the EPA recommended 

limits for recreational contact with water at 5 of the 

13 sites on the mainstem of the Bighorn River in the 

reach from Worland, Wyo. (site 43) to Greybull, Wyo. 

(site 58). Concentrations of fecal coliform or E. coli

exceeded the EPA’s recommended limits for recreational contact with water in samples from 16 of the 

26 tributaries sampled, including the mainstem of the 

Shoshone River (site 73 and site 76). 

Goose Creek Basin 

Synoptic sampling of the 24 sites in the Goose 

Creek Basin was conducted during June 27-29, 2000. 

Seven sites on Big Goose Creek, 8 sites on Little Goose 

Creek, 3 sites on Goose Creek, and 6 tributary sites were 

sampled. Fecal-coliform concentrations for 24 samples 

ranged from 10 col/100 mL for Little Goose Creek 

above Davis Creek, near Bighorn, Wyo. (site 88) to 

1,500 col/100 mL for Soldier Creek on County Road 74, 

near Sheridan, Wyo. (site 97). E. coli concentrations for 

21 samples ranged from 4 col/100 mL (site 88) to 800 

col/100 mL (site 97) (fig. 11). 

Data for Big Goose Creek and Little Goose Creek 

are discussed with the mainstem of Goose Creek because 

their drainage areas represent a large part of the Goose 

Creek Basin. Big Goose Creek and Little Goose Creek 

form Goose Creek at their confluence in Sheridan, Wyo. 

Fecal-coliform concentrations on Big Goose Creek 

ranged from 23 col/100 mL at the upstream-most site 

(site 79) to 1,100 col/100 mL upstream from the Sheridan, Wyo. urban area on Highway 331 (site 84), and 

E. coli concentrations ranged from 15 col/100 mL 

(site 79) to 430 col/100 mL at Kendrick Park in Sheridan, 

Wyo. (site 86). Fecal-coliform concentrations on Little 

Goose Creek ranged from 10 col/100 mL above Davis 

Creek, near Big Horn, Wyo. (site 88) to 280 col/100 mL 

on Highway 87 near Banner, Wyo. (site 92), and E. coli

concentrations ranged from 4 col/100 mL (site 88) to 

200 col/100 mL at two sites on Highway 87 (site 92 and 

site 93). Fecal-coliform concentrations on Goose Creek 

ranged from 600 col/100 mL at 11th Street in Sheridan, 

Wyo. (site 96) to 300 col/100 mL near Acme, Wyo. 

(site 100). The E. coli concentration was 240 col/100 mL 

in a sample collected below Sheridan, Wyo. (site 99) and 

170 col/100 mL in the sample collected near Acme, 

Wyo. (site 100). 

Six tributary sites were sampled in the Goose Creek 

Basin. Tributaries sampled in the forested, upper Goose 

Creek Basin included West Fork Big Goose Creek, East 

Fork Big Goose Creek and Rapid Creek, which are tributary to Big Goose Creek, and Tepee Creek, which is 

tributary to Little Goose Creek. Fecal-coliform concentrations in the upper basin tributaries ranged from 

55 col/100 mL for the sample from West Fork Big 

Goose Creek near Big Horn, Wyo. (site 78) to 

530 col/100 mL for the sample from East Fork Big 

Goose Creek on Forest Service Road 26 near Big Horn, 

Wyo. (site 77). E. coli concentrations in the upper basin 

tributaries ranged from 53 col/100 mL for the sample 

from West Fork Big Goose Creek near Big Horn, Wyo. 

(site 78) to 580 col/100 mL for the sample from East 

Fork Big Goose Creek on Forest Service Road 26 near 

Big Horn, Wyo. (site 77). A light to moderate rain fell 

during the sampling of sites in the upper basin and may 

have contributed to the high fecal-indicator bacteria at 

East Fork Big Goose Creek. Two sites on Soldier Creek, 

which is tributary to Goose Creek, were sampled. Fecal 

coliform (1,500 col/100 mL) and E. coli concentrations 

(800 col/100 mL) were higher at the upstream site on 

County Road 74, near Sheridan, Wyo. (site 97) than the 

downstream site in Sheridan, Wyo. (site 98). 
SYNOPTIC-STUDY RESULTS 33

Table 9. Sites where sample concentrations of fecal-indicator bacteria exceeded the U.S. Environmental 

Protection Agency’s recommended limits for a single sample for recreational contact with water in the Bighorn 

River Basin, Wyoming, July 2000.

[col/100mL, colonies per 100 milliliters; >, greater than]

Fecal coliform Escherichia coli

>400 col/100 mL

>298 col/100 mL

(Moderate use, 

full-body contact)

>406 col/100 mL

(Light use, 

full-body contact)

>576 col/100 mL

(Infrequent use, 

full-body contact)

Owl Creek (site 30) Owl Creek (site 29) Kirby Creek (site 34) Owl Creek (site 30)

Kirby Creek (site 32, 

site 33, and site 34)

Bighorn River (site 43) Sage Creek (site 42) Kirby Creek (site 32 and 

site 33)

Nowater Creek (site 40) Beaver Creek (site 65) Bighorn River (site 58) Nowater Creek (site 40)

Fifteenmile Creek 

(site 41)

Bitter Creek (site 71) Fifteenmile Creek 

(site 41)

Sage Creek (site 42) Slick Creek (site 44)

Bighorn River (site 43, 

site 45, site 46, site 52, 

and site 58)

Bighorn River (site 45, 

site 46, and site 52)

Slick Creek (site 44) Greybull River (site 56 

and site 57)

Greybull River (site 56 

and site 57)

Dry Creek (site 59 and 

site 60)

Dry Creek (site 59 and 

site 60)

Granite Creek (site 62)

Granite Creek (site 62) Shell Creek (site 66)

Beaver Creek (site 65) Whistle Creek (site 72)

Shell Creek (site 66) Shoshone River (site 73 

and site 76)

Bitter Creek (site 71) Foster Gulch (site 74)

Whistle Creek (site 72) Sage Creek (site 75)

Shoshone River (site 73 

and site 76)

Foster Gulch (site 74)

Sage Creek (site 75)
34 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

Figure 11. Fecal-indicator-bacteria concentrations for samples collected in the Goose Creek Basin, Wyoming, June 2000.

Less than 1-30

Less than 1-30
SYNOPTIC-STUDY RESULTS 35

Samples from all of the sites on Big Goose Creek 

except the two upstream most sites (site 79 and site 81) 

exceeded at least one of the EPA’s recommended limits 

for a single sample for recreational contact with water 

for fecal coliform or E. coli (table 10). None of the 

samples for the synoptic study collected on Little Goose 

Creek exceeded the EPA’s recommended limits for recreational contact with water (table 3). Tributary sites 

that had concentrations exceeding at least one of the 

EPA’s recommended limits for recreational contact 

with water include East Fork Big Goose (site 77), Tepee 

Creek (site 87), and Soldier Creek (site 97 and site 98). 

The Wyoming Department of Environmental Quality 

(2000) has listed Big Goose Creek, Little Goose Creek, 

Goose Creek, and Soldier Creek as impaired by fecal 

coliform in the 305(b) report for 2000. 

Distribution of Fecal-Indicator Bacteria by 

Land Cover

Synoptic-sampling sites were located in various 

land-cover settings of the YRB to assess the distribution 

of fecal-indicator bacteria as it related to land cover in 

the Wind River, Bighorn River, and Goose Creek 

Basins. Land-cover classes for the synoptic-study sites 

include: forested, rangeland, agricultural, and urban. 

The distribution of the land cover by basin is summarized in table 11. The fewest sites were in the forested 

land-cover classification because several of the sites 

initially selected to represent forested land-cover were 

actually classified in the NLCD as shrubland or herbaceous upland natural/semi-natural vegetation. Also, 

road conditions and driving times to remote forested 

areas made sampling sites in these areas prohibitive. 

Table 10. Sites where sample concentrations of fecal-indicator bacteria exceeded the U.S. Environmental 

Protection Agency’s recommended limits for a single sample for recreational contact with water in the Goose Creek 

Basin, Wyoming, June 2000.

[col/100 mL, colonies per 100 milliliters; >, greater than]

Fecal coliform Escherichia coli

>400 col/100 mL

>298 col/100 mL

(Moderate use, 

full-body contact)

>406 col/100 mL

(Light use, 

full-body contact)

>576 col/100 mL

(Infrequent use, 

full-body contact)

East Fork Big Goose 

Creek (site 77)

Tepee Creek (site 87) Big Goose Creek 

(site 86)

East Fork Big Goose 

Creek (site 77)

Big Goose Creek 

(site 82, site 83, site 84, 

site 85, and site 86)

Big Goose Creek 

(site 82 and site 85)

Soldier Creek (site 97 

and site 98)

Goose Creek (site 96)

Soldier Creek (site 97 

and site 98)

Table 11. Sampling sites by land cover in the Wind River, Bighorn River, and Goose Creek Basins, Wyoming, JuneJuly 2000. 

Land-cover classification

Basin

Total number 

of sampling 

sites (n) Forested Rangeland Agricultural Urban

Wind River 23 1 19 1 2

Bighorn River 53 2 34 13 4

Goose Creek 24 4 7 8 5

Total 100 7 60 22 11
36 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

Boxplots summarizing the statistical distribution of 

fecal-indicator-bacteria concentrations for each land 

cover are presented in figure 12. The highest median 

concentrations of fecal coliform (540 col/100 mL) and 

E. coli (420 col/100 mL) for all samples were for sites 

with an urban land cover. The maximum concentrations 

of fecal coliform (3,000 col/100 mL) and E. coli

( 2,800 col/100 mL) for all samples were from sites with 

an agricultural land cover. The lowest median concentrations of fecal coliform (130 col/100 mL) and E. coli

(67 col/100 mL) were for samples from sites with a forested land cover. 

Results of a Kruskal-Wallis test indicate that the 

fecal-indicator-bacteria concentrations were not significantly different between land covers at a 95 percent confidence level for fecal-coliform concentrations 

(p-value =0.08) or E. coli concentrations (p-value=0.19). 

The median concentrations for sites with the forested 

and rangeland land cover were 2 to 3 times lower than 

the median concentrations for sites with agricultural and 

urban land covers; however, the variance of the fecalindicator-bacteria concentrations was fairly wide for 

each land-cover classification. This indicates that while 

streams in agricultural and urban areas may be more 

likely to have elevated fecal-indicator-bacteria, low and 

high concentrations may occur for any of the land-cover 

areas in these basins. In this study, the forested sites 

were located in basins with multiple uses, including recreational use and grazing, which are typical for Wyoming’s forested basins. In 1974, a study in a forested 

basin in southern Wyoming found fecal-coliform concentrations were higher in basins with multiple uses 

compared to natural areas without these uses (Skinner 

and others, 1974).

Relation of Esherichia coli to Fecal Coliform 

The concentrations of fecal coliform and E. coli in 

samples during the synoptic study were comparable, 

indicating that historical fecal-coliform data generally 

will be a useful indicator of E. coli presence when the 

State of Wyoming transitions to E. coli criteria for waterquality monitoring in 2003 (C. Harnish, Wyoming 

Department of Environmental Quality, oral commun., 

2002). Relations between fecal coliform and E. coli for 

the Wind River, Bighorn River, and Goose Creek 

Basins, and for the combined data set are presented in 

figure 13. Spearman’s rank correlation shows a strong 

and positive correlation in each basin between fecal 

coliform and E. coli—varying only slightly between the 

basins. Spearman’s Rho was 0.938 in the Wind River 

Basin, 0.981 in the Bighorn River Basin, 0.961 in the 

Goose Creek Basin, and 0.976 for the combined data set. 

For this analysis, data from sites on tributaries and mainstems were grouped together within a basin because sitespecific relations could not be determined with only one 

sample per site. The strong correlation between fecal 

coliform and E. coli for the pooled data sets does not 

ensure that the relation between them is the same for 

individual streams. Studies have found that regression 

equations derived to predict E. coli based on fecal 

coliform differ from site to site, due in part to differences 

in sources of bacteria (Francy and others, 1993). 

The lines on the scatter plots in figure 13 indicate 

where samples with an E. coli to fecal-coliform ratio of 

0.5 and 1.0 would plot and where 50 to 100 percent of 

the fecal coliform would be in the form of E. coli. Most 

of the data plot between these lines, indicating that the 

majority of the fecal coliform were E. coli in the samples 

collected during the synoptic study. Data points that plot 

above the 1.0 line represent E. coli concentrations 

greater than the fecal-coliform concentrations. Because 

E. coli is a subset of fecal-coliform bacteria, these data 

reflect some of the variability about the fecal-indicatorbacteria concentrations seen in quality-assurance replicate samples. E. coli concentrations also may exceed 

fecal-coliform concentrations owing to differences in the 

processing method—the E. coli method uses a smaller 

filter pore size and has a resuscitation step that the fecalcoliform method does not have.

Relation of Fecal-Indicator Bacteria to WaterQuality Characteristics

Environmental conditions such as water characteristics affect the survival rate of fecal-indicator bacteria 

once they leave the digestive tract of warm-blooded animals. Selected physical water-quality characteristics 

were measured in the field and sediment samples were 

collected for analysis during the synoptic sampling in the 

Wind River, Bighorn River, and Goose Creek Basins to 

provide data on the environmental conditions. A wide 

range of stream settings was selected for the synoptic 

study, including large perennial streams that originate 

from mountainous sources and small intermittent 

streams that originate in the plains. The wide range of 

settings of the streams sampled for this study is reflected 

in the wide range of field measurement values (table 3).
SYNOPTIC-STUDY RESULTS 37

Figure 12. Fecal-indicator-bacteria concentrations by land-cover classification in the Wind River, Bighorn River, and Goose 

Creek Basins, Wyoming, June-July 2000. 
38 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

Figure 13. Fecal-coliform and Escherichia coli relations in the Wind River, Bighorn River, and Goose Creek Basins, 

Wyoming, June-July 2000. 

Spearman’s rank correlation coefficient was used 

to determine the strength of the relation between the 

fecal-indicator bacteria and selected water-quality constituents for the pooled dataset of all samples (table 12) 

because site-specific relations were not possible with 

one data point. Fecal-indicator bacteria were poorly 

related to streamflow, water temperature, dissolved 

oxygen, pH, specific conductance, and alkalinity. The 

weak correlations for the pooled dataset probably are 

the result of the wide range of stream settings that were 

sampled. Other studies have shown that streamflow, in 

particular, can be an important factor controlling fecalindicator-bacteria concentrations at a stream site as 

bacteria can be carried to the stream with overland flow 

(Stephenson and Street, 1978; Elder, 1987; Hunter and 

others, 1992; Barbe ́ and Francis, 1995; Myers and others, 1998; Baudart and others, 2000). 

Fecal-indicator bacteria and turbidity (Spearman’s 

Rho values of 0.662 and 0.640 for fecal coliform and 

E. coli, respectively) and sediment (Spearman’s Rho 

values of 0.628 and 0.636 for fecal coliform and E. coli, 

respectively) had moderate correlations, even given the 

wide range of stream settings that were sampled. The 
SYNOPTIC-STUDY RESULTS 39

Table 12. Spearman’s rank correlation coefficients between fecal-indicator bacteria and water-quality 

constituents in the Wind River, Bighorn River, and Goose Creek Basins, Wyoming, June-July 2000.

Spearman’s rank correlation coefficient

Water-quality constituent Fecal coliform Escherichia coli

Streamflow -0.286 -0.313

Water temperature .102 .140

Dissolved Oxygen -.308 -.340

pH -.076 -.026

Specific conductance .384 .436

Alkalinity .407 .455

Turbidity .662 .640

Sediment .628 .636

positive correlation of bacteria and solid particles canresult from overland flow carrying bacteria-laden sediment to streams (Hunter and others, 1992) or 

resuspension of sediment from the stream bottom, 

either by increased flows or human or animal traffic in 

the stream. Bacteria that are deposited with stream 

sediments can survive for extended periods in the protective environment of the sediment (Sherer and others, 1992). Fecal-coliform concentrations that were 

100 to 1,000 times greater than concentrations in the 

water column have been found in the associated sediments (Van Donsel and Geldreich, 1971). No major 

storms producing significant amounts of overland 

flow on a large scale occurred during the synoptic 

study; however, isolated short storms locally may have 

contributed to fecal-indicator bacteria and turbidity or 

sediment concentrations at some sites. 

Microbial Source Tracking 

Determining the sources of fecal contamination in 

a basin can assist water managers in developing wasteload allocations, establishing best management practices, and assessing health risk presented by the contamination. Fecal-indicator bacteria are nearly always 

present at some level in Wyoming streams because 

sources for the bacteria exist in the basins. The presence of E. coli indicates the presence of fecal contamination from warm-blooded animals, but does not 

differentiate between host sources. 

The two sites selected to test the DNA method 

using discriminant analysis of ribotypes for E. coli isolates were the Bighorn River at Basin, Wyo. (site 52) 

and Bitter Creek near Garland, Wyo. (site 71). Historical data from these sites include high fecal-indicatorbacteria concentrations. Both sites were listed as being 

impaired by fecal coliform for contact recreation in the 

Wyoming 305(b) water-quality assessment for 2000 

(Wyoming Department of Environmental Quality, 

2000). Eight E. coli isolates were cultured for the Bighorn River at Basin, Wyo. (site 52) and seven isolates 

were cultured for Bitter Creek near Garland, Wyo. 

(site 71). 

Source classifications for the isolates for the sample from the Bighorn River at Basin, Wyo. (site 52) and 

Bitter Creek near Garland, Wyo. (site 71) are presented 

in figure 14. The source classification determinations 

are presented using three different confidence levels—

70 percent, 80 percent, and 90 percent. The confidence 

level of 70 percent represents the case where there is a 

30 percent probability that a classification determination is incorrect. The confidence level of 90 percent 

represents the case where there is a 10 percent probability that a classification determination is incorrect. 

Using the lower confidence levels results in fewer 

unknown determinations, but increases the chance of 

an incorrect classification. 

Using a confidence level of 70 percent for the Bighorn River at Basin, Wyo. (site 52), 2 isolates were classified as human, 5 isolates as nonhuman, and 1 isolate as 

unknown. Using a confidence level of 90 percent for 

site 52, 1 isolate was classified as human, 3 isolates as 
40 A SYNOPTIC STUDY OF FECAL-INDICATOR BACTERIA 

nonhuman, and 4 isolates as unknown. Using a confidence level of 70 percent for Bitter Creek near Garland, 

Wyo. (site 71), 1 isolate was classified as human and 

6 isolates as nonhuman. Using a confidence level of 

90 percent for site 71, 1 isolate was classified as human, 

4 isolates as nonhuman, and 2 isolates as unknown. 

These data indicate that both human and nonhuman 

sources contribute E. coli to the Bighorn River and Bitter Creek, and a higher percentage of the known isolates 

are from nonhuman sources. Whether the nonhuman 

sources are pets, agricultural animals, or wildlife was 

not determined for this study.

Figure 14. Source determinations of Escherichia 

coli isolates for samples from the Bighorn River 

at Basin, Wyoming (site 52) and Bitter Creek 

near Garland, Wyoming (site 71) in the Bighorn 

River Basin, Wyoming, July 2000.

SUMMARY

A synoptic study of fecal-indicator bacteria was 

conducted during June and July 2000 in the Wind River, 

Bighorn River, and Goose Creek Basins in Wyoming as 

part of the U.S. Geological Survey’s National WaterQuality Assessment Program for the Yellowstone River 

Basin. Twenty-three sites were in the Wind River 

Basin, 53 sites were in the Bighorn River Basin, and 

24 sites were in the Goose Creek Basin. Samples were 

collected in the summer when human exposure to pathogens through recreational contact with water typically is 

the highest. Fecal-coliform concentrations for 100 samples ranged from 2 to 3,000 col/100 mL (colonies per 

100 milliliters). Escherichia coli (E. coli) concentrations for 97 samples ranged from 1 to 2,800 col/100 mL.

Fecal-indicator-bacteria concentrations varied significantly by basin. Samples from the Bighorn River 

Basin had the highest median concentrations for fecal 

coliform of 340 col/100 mL and for E. coli of 

300 col/100 mL. Samples from the Goose Creek Basin 

had median concentrations for fecal coliform of 

330 col/100 mL and for E. coli of 200 col/100 mL. Samples from the Wind River Basin had the lowest median 

concentrations for fecal coliform of 50 col/100 mL and 

for E. coli of 62 col/100 mL. The lower concentrations 

in the Wind River Basin were not directly related to the 

population densities of livestock and humans in the 

basins. 

The Bighorn River Basin had the highest percentage of samples (49.1 percent) with fecal-coliform concentrations higher than EPA’s recommended limit for a 

single sample for recreational contact with water of 

400 col/100 mL. Concentrations of fecal coliform in the 

Goose Creek Basin exceeded the recommended limit in 

37.5 percent of the samples. Concentrations of fecal 

coliform in the Wind River Basin exceeded the recommended limit in 8.7 percent of the samples. In the Bighorn River Basin, 50.9 percent of the samples for E. coli

exceeded the EPA recommended limit for a single sample for moderate use, full-body recreational contact of 

298 col/100 mL, compared to 33.3 percent in the Goose 

Creek Basin and 13.0 percent in the Wind River Basin. 

In the Bighorn River Basin, 37.7 percent of the samples 

of E. coli exceeded the EPA recommended limit for 

infrequent use, full-body recreational contact of 

576 col/100 mL, compared to 14.3 percent in the Goose 

Creek Basin and 4.3 percent in the Wind River Basin. 
REFERENCES 41

The distribution of fecal-indicator-bacteria concentrations by land cover was determined relative to the 

dominant land cover 500 meters upstream of each 

sample site. The highest median concentrations for 

fecal coliform of 540 col/100 mL and for E. coli of 

420 col/100 mL were for samples from sites with an 

urban land cover. The maximum concentrations for 

fecal coliform of 3,000 col/100 mL and for E. coli of 

2,800 col/100 mL were in samples from sites with an 

agricultural land cover. The lowest median concentrations for fecal coliform of 130 col/100 mL and for 

E. coli of 67 col/100 mL were for samples from sites 

with a forested land cover. Although the median concentrations for sites with the forested and rangeland land 

cover were 2 to 3 times lower than the median concentrations for sites with agricultural and urban land covers, 

the results of a Kruskal-Wallis test indicated the fecalindicator-bacteria concentrations were not statistically 

different between land covers. 

Relations between fecal coliform and E. coli for the 

Wind River, Bighorn River, and Goose Creek Basins 

were strong and positive. Spearman’s Rho was 0.938 in 

the Wind River Basin, 0.981 in the Bighorn River Basin, 

and 0.961 in the Goose Creek Basin. These results indicate that the distribution of fecal coliform and E. coli in 

Wyoming streams is comparable and historical fecalcoliform data generally will be a useful indicator of E. 

coli presence when the State of Wyoming transitions to 

using E. coli for water-quality criteria in 2003.

Fecal-indicator bacteria were not corelated with the 

field constituents of streamflow, pH, specific conductance, dissolved oxygen, water temperature, and alkalinity. Fecal-indicator bacteria were moderately correlated 

with turbidity (Spearman’s Rho values of 0.662 and 

0.640 for fecal coliform and E. coli, respectively) and 

sediment (Spearman’s Rho values of 0.628 and 0.636 

for fecal coliform and E. coli, respectively). 

A microbial source-tracking method was tested as 

part of the synoptic study. E. coli isolates in samples 

from the Bighorn River at Basin, Wyo. and Bitter Creek 

near Garland, Wyo. were analyzed using discriminant 

analysis of ribotype patterns. Using a confidence level 

of 90 percent for the Bighorn River at Basin, Wyo., 

1 isolate was classified as human, 3 isolates as nonhuman, and 4 isolates as unknown. Using a confidence 

level of 90 percent for Bitter Creek near Garland, Wyo., 

1 isolate was classified as human, 4 isolates as nonhuman, and 2 isolates as unknown. These data indicate 

that human and nonhuman sources contribute E. coli to 

stream waters in both basins, and a higher percentage of 

the known isolates are from nonhuman sources. 

REFERENCES

Barbe ́, D.E., and Francis, J.C., 1995, An analysis of seasonal fecal coliform levels in the Tchefuncte River: 

Water Resources Bulletin, v. 31, no. 1, p. 141-146.

Baudart, J., Grabulos, J., Barusseau, J. P., and Lebaron, P., 

2000, Salmonella spp. and fecal coliform loads in 

coastal waters from a point vs. nonpoint source of pollution: Journal of Environmental Quality, v. 29, 

p. 241-250. 

Cabelli, V.J., 1977, Indicators of recreational water quality, 

in Hoadley, A.W., and Dutka, B.J., eds., Bacterial indicators/ health hazards associated with water, 1977: 

American Society for Testing and Materials, ASTM 

STP 635, p. 222-238.

Carson, C.A., Shear, B.L., Ellersieck, M.R., and Asfaw, A., 

2001, Identification of fecal Escherichia coli from 

humans and animals by ribotyping: Applied and Environmental Microbiology, v. 67, no. 4, p. 1503-1507.

Clark, M.L., and Norris, J.R., 2000, Occurrence of fecal 

coliform bacteria in selected streams in Wyoming, 

1990-99: U.S. Geological Survey Water-Resources 

Investigations Report 00-4198, 8 p. 

Dombek, P.E., Johnson, L.K., Zimmerley, S.T., and Sadowsky, M.J., 2000, Use of repetitive DNA sequences 

and the PCR to differentiate Escherichia coli isolates 

from human and animal sources: Applied and Environmental Microbiology, v. 66, no. 6, p. 2572-2577. 

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