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Estimated fecal coliform bacteria concentrations using near real-time continuous water-quality and streamflow data from five stream sites in Chester County, Pennsylvania, 2007–16

Scientific Investigations Report 2017-5075

Prepared in cooperation with the Chester County Health Department and Chester County Water Resources Authority
By:
ORCID iD
https://doi.org/10.3133/sir20175075

Links

  • Document: Report (11.2 MB pdf)
  • Appendixes:
    • Appendix 1 (436 KB pdf) - Model Archive Summary for Best-Fit Regression Developed to Estimate Fecal Coliform Concentration at Station 01480617; West Branch Brandywine Creek at Modena, Pennsylvania
    • Appendix 2 (434 KB pdf) - Model Archive Summary for Best-Fit Regression Developed to Estimate Fecal Coliform Concentration at Station 01480870; East Branch Brandywine Creek below Downingtown, Pennsylvania
    • Appendix 3 (429 KB pdf) - Model Archive Summary for Best-Fit Regression Developed to Estimate Fecal Coliform Concentration at Station 01481000; Brandywine Creek at Chadds Ford, Pennsylvania
    • Appendix 4 (348 KB pdf) - Model Archive Summary for Best-Fit Regression Developed to Estimate Fecal Coliform Concentration at Station 01472157; French Creek near Phoenixville, Pennsylvania
    • Appendix 5 (371 KB pdf) - Model Archive Summary for Best-Fit Regression Developed to Estimate Fecal Coliform Concentration at Station 01478245; White Clay Creek near Strickersville, Pennsylvania
  • Data Release: USGS data release - Archival data for regression models developed to estimate fecal coliform concentrations at five stream sites, Chester County, Pennsylvania (2017): U.S. Geological Survey
  • Download citation as: RIS | Dublin Core

Abstract

Several streams used for recreational activities, such as fishing, swimming, and boating, in Chester County, Pennsylvania, are known to have periodic elevated concentrations of fecal coliform bacteria, a type of bacteria used to indicate the potential presence of fecally related pathogens that may pose health risks to humans exposed through water contact. The availability of near real-time continuous stream discharge, turbidity, and other water-quality data for some streams in the county presents an opportunity to use surrogates to estimate near real-time concentrations of fecal coliform (FC) bacteria and thus provide some information about associated potential health risks during recreational use of streams.

The U.S. Geological Survey (USGS), in cooperation with the Chester County Health Department (CCHD) and the Chester County Water Resources Authority (CCWRA), has collected discrete stream samples for analysis of FC concentrations during March–October annually at or near five gaging stations where near real-time continuous data on stream discharge, turbidity, and water temperature have been collected since 2007 (or since 2012 at 2 of the 5 stations). In 2014, the USGS, in cooperation with the CCWRA and CCHD, began to develop regression equations to estimate FC concentrations using available near real-time continuous data. Regression equations included possible explanatory variables of stream discharge, turbidity, water temperature, and seasonal factors calculated using Julian Day with base-10 logarithmic (log) transformations of selected variables.

The regression equations were developed using the data from 2007 to 2015 (101–106 discrete bacteria samples per site) for three gaging stations on Brandywine Creek (West Branch Brandywine Creek at Modena, East Branch Brandywine Creek below Downingtown, and Brandywine Creek at Chadds Ford) and from 2012 to 2015 (37–38 discrete bacteria samples per site) for one station each on French Creek near Phoenixville and White Clay Creek near Strickersville. Fecal coliform bacteria data collected by USGS in 2016 (about nine samples per site) were used to validate the equations. The best-fit regression equations included log turbidity and seasonality factors computed using Julian Day as explanatory variables to estimate log FC concentrations at all five stream sites. The adjusted coefficient of determination for the equations ranged from 0.61 to 0.76, with the strength of the regression equations likely affected in part by the limited amount and variability of FC bacteria data. During summer months, the estimated and measured FC concentrations commonly were greater than the Pennsylvania Department of Environmental Protection established standards of 200 and 400 colonies per 100 milliliters for water contact from May through September at the 5 stream sites, with concentrations typically higher at 2 sites (White Clay Creek and West Branch Brandywine Creek at Modena) than at the other 3 sites. The estimated concentrations of FC bacteria during the summer months commonly were higher than measured concentrations and therefore could be considered cautious estimates of potential human-health risk. Additional water-quality data are needed to maintain and (or) improve the ability of regression equations to estimate FC concentrations by use of surrogate data.

Suggested Citation

Senior, L.A., 2017, Estimated fecal coliform bacteria concentrations using near real-time continuous water-quality and streamflow data from five stream sites in Chester County, Pennsylvania, 2007–16: U.S. Geological Survey Scientific Investigations Report 2017–5075, 46 p., https://doi.org/10.3133/sir20175075.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Methods
  • Estimated Fecal Coliform Bacteria Concentrations 
  • Summary and Conclusions 
  • References Cited
  • Appendix 1. Model Archive Summary for Best-Fit Regression Developed to Estimate Fecal Coliform Concentration at Station 01480617; West Branch Brandywine Creek at Modena, Pennsylvania
  • Appendix 2. Model Archive Summary for Best-Fit Regression Developed to Estimate Fecal Coliform Concentration at Station 01480870; East Branch Brandywine Creek below Downingtown, Pennsylvania
  • Appendix 3. Model Archive Summary for Best-Fit Regression Developed to Estimate Fecal Coliform Concentration at Station 01481000; Brandywine Creek at Chadds Ford, Pennsylvania
  • Appendix 4. Model Archive Summary for Best-Fit Regression Developed to Estimate Fecal Coliform Concentration at Station 01472157; French Creek near Phoenixville, Pennsylvania
  • Appendix 5. Model Archive Summary for Best-Fit Regression Developed to Estimate Fecal Coliform Concentration at Station 01478245; White Clay Creek near Strickersville, Pennsylvania

Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Estimated fecal coliform bacteria concentrations using near real-time continuous water-quality and streamflow data from five stream sites in Chester County, Pennsylvania, 2007–16
Series title:
Scientific Investigations Report
Series number:
2017-5075
DOI:
10.3133/sir20175075
Year Published:
2017
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Pennsylvania Water Science Center
Description:
Report: x, 46 p.; Appendix 1-5; Data Release
Country:
United States
State:
Pennsylvania
County:
Chester County
Online Only (Y/N):
Y
Additional Online Files (Y/N):
Y