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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

By Melanie L. Clark and Merry E. Gamper

Prepared as part of the National Water-Quality Assessment Program

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Photo of streamAbstract

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. Fecal-coliform 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 conduc-tance, 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.


Table of Contents

Abstract

Introduction

Background

Purpose and scope

Acknowledgments

Environmental setting

Sampling sites and methods

Field measurements and sample collection

Data analysis

Microbial source tracking

Synoptic-study results

Sampling conditions

Quality-control samples

Distribution of fecal-indicator bacteria by basin

Wind River Basin

Bighorn River Basin

Goose Creek Basin

Distribution of fecal-indicator bacteria by land cover

Relation of Escherichia coli to fecal coliform

Relation of fecal-indicator bacterial to water-quality characteristics

Microbial source tracking

Summary

References


Water Resources of Wyoming


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