Lisa A. Senior Linda F. Zarr Matthew C. Gyves 20250808 Version 1.0: August 2025; Version 1.1: May 2026; Comma-Separated Values (.csv), Portable Document Format (.pdf), Text Files (.txt) https://doi.org/10.5066/P13RKCJO Lisa A. Senior 20170901 Version 1.0: September 2017; Version 1.1: April 2023; Version 1.2: March 2024 publication Regressions were developed to predict Escherichia coli (E. coli) concentrations at four U.S. Geological Survey (USGS) gages on streams in Chester and Delaware Counties in southeastern Pennsylvania. The regression analysis was based on 2019-24 discrete E. coli concentrations measured in samples collected approximately monthly by USGS from April to October and concurrent available streamflow and water-quality variables. Available water-quality variables included turbidity (Turb), water temperature, specific conductance (SC), pH and dissolved oxygen concentration measured continuously by monitors operated by USGS at the gages. The data used for regression and results of regression analysis are described in the Model Archive Summary for each site. Through the regression analysis, the variables that best predicted E. coli (EC) relative to water-quality standards were identified. Log10(Turb), seasonality terms, sin2piD_365 and cos2piD_365, and for some sites, SC, selected as explanatory variables in linear regression equations as the best predictors of log10(EC) based on residual plots and regression statistics. Sensitivity, specificity, positive predictive values, and negative predictive values were computed for the regression dataset to assess model reliability for predicting concentrations above and below a Pennsylvania Department of Environmental Protection (PADEP) standard of 410 colonies forming units (CFU) per 100 milliliters (mL) for E. coli in recreational water for the swimming season of May 1 through September 30. The data collection and regression analyses were done by USGS in cooperation with Chester County Health Department (CCHD) and Chester County Water Resources Authority (CCWRA). First released August 2025 Revised April 2026 (ver. 1.1) Data on E. coli concentrations were collected by USGS in cooperation with the Chester County Health Department (CCHD) and Chester County Water Resources Authority (CCWRA) to provide information about potential human-health risks for recreational use of selected streams. Regression equations were developed to provide near-real time estimates of E. coli concentrations using surrogate water-quality variables which are continuously monitored at USGS gages. 20190418 20240926 ground condition Complete None planned -76.1682 -75.4541 40.2500 39.6963 Watersheds in Chester and Delaware Counties, Pennsylvania ISO 19115 Topic Category biota USGS Thesaurus regression analysis bacteria surface water quality USGS Metadata Identifier USGS:67e46236d34ee7f14221756b None Chester County, Pennsylvania Delaware County, Pennsylvania No access constraints. Please see 'Distribution Information' for details. These data are marked with a Creative Common CC0 1.0 Universal License. These data are in the public domain and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Lisa A. Senior USGS - Northeast Region Hydrologist mailing and physical

408 Boot Road

Ambler PA 19002 717-503-2367 lasenior@usgs.gov Chester County Health Department and Chester County Water Resources Authority. Reported discharge values are estimated to be accurate within about 10 percent and were determined from gage height and corresponding streamflow value at the time of sample collection at four USGS gaging stations. Using criteria for continuous water-quality data described by Wagner and others (2006), reported water temperature values measured by USGS are estimated to be accurate within about 0.2 degrees Celsius, reported specific conductance measured by USGS are estimated to be accurate within about 3 to 10 percent, and reported turbidity values are estimated to be accurate within about 5 to 15 percent or within 0.5 to 1.5 turbidity units. Discrete-sample Escherichia coli (E. coli) bacteria concentrations measured by USGS and reported in most probable number (MPN) per 100 milliliters (mL) are estimated be be accurate to within about 25 percent based on 26 replicate samples collected from 2021 through 2024 at the 4 sites. Differences in bacteria concentrations for most (80 percent) of the 26 replicate samples analyzed for E. coli ranged from plus or minus about 25 percent, and the mean and median differences were near 0 (about 2 and 1 percent, respectively); the interquartile range of differences in bacteria concentrations was about plus or minus 15 percent. All data were subject to multiple levels of review which included checking for sampling errors, numerical errors, data entry errors, duplication, omission, expected range of results, model review, final data review, and metadata review. Dataset includes all values of discrete E. coli concentrations and associated streamflow and water-quality collected and/or measured by USGS during 2019-24; entire dataset was reviewed for completeness and suitability for regression analysis to estimate E. coli concentrations at four USGS gaging stations. Some observations, including environmental replicates for E. coli, greater-than value for E. coli, and outliers were removed from dataset used for regression analysis. 100 feet Each year from April to October from 2019 through 2024, discrete (grab) samples for analysis of Escherichia coli (E. coli) bacteria concentrations were collected approximately monthly at or near four stream sites in Chester and Delaware Counties in southeastern Pennsylvania. The four stream sites are at or near USGS gaging stations where continuous data for stream discharge and water-quality data are collected by USGS and include USGS stations 01472157, French Creek at Phoenixville, PA, 01478245, White Clay Creek near Strickersville, PA, 01480870, East Branch Brandywine Creek below Downingtown, PA, and 01481000, Brandywine Creek at Chadds Ford, PA. Discrete measurements of stream water quality (water temperature, specific conductance, pH, dissolved oxygen concentration, sand turbidity) were made at the time of discrete sample collection. Analyses for E. coli were done at the USGS Pennsylvania Water Science Downingtown Field Office using methods described in the model summaries included as .pdf files in this data release. The discrete data on bacteria concentrations and water quality were collected for the purpose of developing regression equations to estimate near-real time E.coli concentrations using near-real time data continuous available water quality and streamflow data measured at the gaging stations. 20250312 Data on discrete concentrations of Escherichia coli (E. coli) bacteria and concurrent measurements of stream discharge and water quality were retrieved from USGS National Water Information System (NWIS) database for four stream sites in Chester and Delaware Counties, Pennsylvania for calendar years 2019 through 2024. The four stream sites are at or near USGS stations 01472157, French Creek at Phoenixville, PA, 01478245, White Clay Creek near Strickersville, PA, 01480870, East Branch Brandywine Creek below Downingtown, PA, and 01481000, Brandywine Creek at Chadds Ford, PA. The data on E. coli concentrations, which consist of results of analyses for grab samples collected approximately monthly by USGS during the period of April to October each year, were compiled for use in developing regression equations to estimate E. coli concentrations using available streamflow, water-quality, and seasonal variables. 20250404 Regression equations to estimate Escherichia coli (E. coli) concentrations using available streamflow, water-quality, and seasonal variables were developed using statistical software and programs as described in the model summaries included as .pdf files in this data release and following procedures previously applied for regressions to estimate fecal coliform concentrations at the same stream sites (Senior, 2017). The water-quality variables, turbidity, water temperature, specific conductance, pH, and dissolved oxygen concentration were considered in regression analysis, if available. Observations with E. coli concentrations reported as greater-than-values and environmental replicates were excluded from regression datasets for the four sites; additionally, some outliers flagged as identified by statistical measures were also excluded if determined suspect after further review. Both regression input datasets and all available observations (including greater-than values, replicates, and outliers) formatted as .csv files are also part of this data release. Details of regression development are described in the Model Archive Summary for each site as part of this data release. Regressions were checked and press values were calculated using a statistical program, USGS-R/smwrStats · GitHub, independent of programs used to develop regressions. The model summaries include the regression equation, statistics for that regression equation, as well as sensitivity, specificity, positive predictive values, and negative predictive values calculated for the number of observations in the regression dataset and additionally for the regression dataset plus the greater-than-values. 20250606 01481000_BrandywineChaddsFord_ECmodel_2019_2024input.csv Comma Separated Value (CSV) file containing discrete streamflow, water-quality, and bacteria concentration data; these 2019-24 data used as input to linear regression models developed to estimate E. coli bacteria concentrations at USGS station 01481000 Brandywine Creek at Chadds Ford, PA. Producer Defined sitename USGS station (site) name Producer Defined Brandywine Creek at Chadds Ford, PA USGS station (site) name Producer defined siteno USGS station (site) number Producer Defined USGS-01481000 Agency-USGS station (site) identification number Producer defined datetime Date and local time of sample collection or measurement in either Eastern Standard Time or Eastern Daylight Time Producer Defined 4/18/2019 12:00 9/26/2024 14:00 m/d/yyyy hh:mm JD Julian day (of calendar year) Producer Defined 107 292 1 day Q Stream discharge (instantaneous) Producer Defined 121 958 cubic feet per second temp_degC Water temperature Producer Defined 12.4 27.4 degrees Celsius (deg C) SC_uscm Specific conductance Producer Defined 258 438 microsiemens per centimeter (uS/cm) at 25 degrees Celsius DO_mgL Dissolved oxygen concentration Producer Defined 7.5 13.6 milligrams per liter (mg/L) pH pH Producer Defined 7.33 8.7 standard units EC_mpn E. coli (EC) concentration Producer Defined 19 4350 most probable number per 100 milliliters (MPN/100 mL) Turb_fnu Turbidity Producer Defined 0.4 18.5 formazin nephelometric units (fnu) log10EC log10(E. coli concentration) Producer Defined 1.278753601 3.638489257 log10(most probable number per 100 milliliters, MPN/100 mL) log10Turb log10(Turbidity) Producer Defined -0.397940009 1.267171728 log10(formazin nephelometric units, fnu) log10SC log10(Specific conductance) Producer Defined 2.411619706 2.641474111 log10(microsiemens per centimeter, uS/cm at 25 deg C) sin2piD_365 seasonality term sin(2piJD/365) Producer Defined -0.999546162 0.963470965 cos2piD_365 seasonality term cos(2piJD/365) Producer Defined -0.999962936 0.309012956 01481000_BrandywineChaddsFord_ECdata_2019_2024exclude.csv Comma Separated Value (CSV) file containing concurrent discrete streamflow, water-quality, and bacteria concentration data for 2019-24 that were excluded from regression analysis; excluded data include environmental replicates, selected flagged values that were investigated and removed as outliers, and values qualified as greater than the maximum reporting levels at USGS station 01481000 Brandywine Creek at Chadds Ford, PA. Producer Defined sitename USGS station (site) name Producer Defined Brandywine Creek at Chadds Ford, PA USGS station (site) name Producer defined siteno USGS station (site) number Producer Defined USGS-01481000 Agency-USGS station (site) identification number Producer defined datetime Date and local time of sample collection or measurement in either Eastern Standard Time or Eastern Daylight Time Producer Defined 8/19/2021 14:30 8/15/2024 14:46 m/d/yyyy hh:mm JD Julian day (of calendar year) Producer Defined 121 257 1 day Q Stream discharge (instantaneous) Producer Defined 145 1200 cubic feet per second (cfs) temp_degC Water temperature Producer Defined 15.6 27.3 degrees Celsius (deg C) SC_uscm Specific conductance Producer Defined 165 438 microsiemens per centimeter (uS/cm) at 25 degrees Celsius DO_mgL Dissolved oxygen concentration Producer Defined 7.0 13.6 milligrams per liter (mg/L) pH pH Producer Defined 7.3 8.6 standard units Rmk_EC Remark code qualifier for E. coli value Producer Defined << empty cell >> No Data Producer defined > greater than Producer defined EC_mpn E. coli (EC) concentration Producer Defined 34 4840 most probable number per 100 milliliters (MPN/100 mL) Turb_fnu Turbidity Producer Defined 0.4 50.0 formazin nephelometric units (fnu) log10EC log10(E. coli concentration) Producer Defined 1.531478917 3.684845362 log10(most probable number per 100 milliliters, MPN/100 mL) log10Turb log10(Turbidity) Producer Defined -0.397940009 1.698970004 log10(formazin nephelometric units, fnu) log10SC log10(Specific conductance) Producer Defined 2.217483944 2.641474111 log10(microsiemens per centimeter, uS/cm at 25 deg C) sin2piD_365 seasonality term sin(2piJD/365) Producer Defined -0.958716754 0.871707181 cos2piD_365 seasonality term cos(2piJD/365) Producer Defined -0.998185697 -0.28436277 Comment Comment for observations excluded from regression dataset Producer Defined Comments for excluded data include: Environmental Replicates, Greater than values, and Outliers 01480870_EBrBrandywineDowningtown_ECmodel_2019_2024input.csv Comma Separated Value (CSV) file containing discrete streamflow, water-quality, and bacteria concentration data; these 2019-24 data used as input to linear regression models developed to estimate E. coli bacteria concentrations at USGS station 01480870, East Branch Brandywine Creek below Downingtown, PA. Producer Defined sitename USGS station (site) name Producer Defined East Branch Brandywine Creek below Downingtown, PA USGS station (site) name Producer defined siteno USGS station (site) number Producer Defined USGS-01480870 Agency-USGS station (site) identification number Producer defined datetime Date and local time of sample collection or measurement in either Eastern Standard Time or Eastern Daylight Time Producer Defined 4/18/2019 12:45 9/26/2024 14:30 m/d/yyyy hh:mm JD Julian day (of calendar year) Producer Defined 107 292 1 day Q Stream discharge (instantaneous) Producer Defined 30 296 cubic feet per second temp_degC Water temperature Producer Defined 13.4 27.8 degrees Celsius (deg C) SC_uscm Specific conductance Producer Defined 251 467 microsiemens per centimeter (uS/cm) at 25 degrees Celsius DO_mgL Dissolved oxygen concentration Producer Defined 8.0 13.5 milligrams per liter (mg/L) pH pH Producer Defined 7.5 8.7 standard units EC_mpn E. coli (EC) concentration Producer Defined 41 5480 most probable number per 100 milliliters (MPN/100 mL) Turb_fnu Turbidity Producer Defined 0.4 34.0 formazin nephelometric units (fnu) log10EC log10(E. coli concentration) Producer Defined 1.612783857 3.738780558 log10(most probable number per 100 milliliters, MPN/100 mL) log10Turb log10(Turbidity) Producer Defined -0.397940009 1.531478917 log10(formazin nephelometric units, fnu) log10SC log10(Specific conductance) Producer Defined 2.399673721 2.669316881 log10(microsiemens per centimeter, uS/cm at 25 deg C) sin2piD_365 seasonality term sin(2piJD/365) Producer Defined -0.999546162 0.963470965 cos2piD_365 seasonality term cos(2piJD/365) Producer Defined -0.999962936 0.309012956 01480870_EBrBrandywineDowningtown_ECdata_2019_2024exclude.csv Comma Separated Value (CSV) file containing concurrent discrete streamflow, water-quality, and bacteria concentration data for 2019-24 that were excluded from regression analysis; excluded data include environmental replicates, selected flagged values that were investigated and removed as outliers, and values qualified as greater than the maximum reporting levels at USGS station 01480870 East Branch Brandywine Creek below Downingtown, PA. Producer Defined sitename USGS station (site) name Producer Defined East Branch Brandywine Creek below Downingtown, PA USGS station (site) name Producer defined siteno USGS station (site) number Producer Defined USGS-01480870 Agency-USGS station (site) identification number Producer defined datetime Date and local time of sample collection or measurement in either Eastern Standard Time or Eastern Daylight Time Producer Defined 7/30/2019 14:00 7/24/2023 12:46 m/d/yyyy hh:mm JD Julian day (of calendar year) Producer Defined 130 292 1 day Q Stream discharge (instantaneous) Producer Defined 42 159 cubic feet per second temp_degC Water temperature Producer Defined 16.1 25.5 degrees Celsius (deg C) SC_uscm Specific conductance Producer Defined 271 450 microsiemens per centimeter (uS/cm) at 25 degrees Celsius DO_mgL Dissolved oxygen concentration Producer Defined 8.0 13.0 milligrams per liter (mg/L) pH pH Producer Defined 7.6 8.4 standard units Rmk_EC Remark code qualifier for E. coli value Producer Defined << empty cell >> No Data Producer defined > greater than Producer defined EC_mpn E. coli (EC) concentration Producer Defined 35 4840 most probable number per 100 milliliters (MPN/100 mL) Turb_fnu Turbidity Producer Defined 0.8 34.0 formazin nephelometric units (fnu) log10EC log10(E. coli concentration) Producer Defined 1.544068044 3.684845362 log10(most probable number per 100 milliliters, MPN/100 mL) log10Turb log10(Turbidity) Producer Defined -0.096910013 1.531478917 log10(formazin nephelometric units, fnu) log10SC log10(Specific conductance) Producer Defined 2.432969291 2.653212514 log10(microsiemens per centimeter, uS/cm at 25 deg C) sin2piD_365 seasonality term sin(2piJD/365) Producer Defined -0.958716754 0.785651025 cos2piD_365 seasonality term cos(2piJD/365) Producer Defined -0.995521129 0.309012956 Comment Comment for observations excluded from regression data set Producer Defined Comments for excluded data include: Environmental Replicates, Greater than values, and Outliers 01472157_FrenchCrk_ECmodel_2019_2024input.csv Comma Separated Value (CSV) file containing discrete streamflow, water-quality, and bacteria concentration data; these 2019-24 data used as input to linear regression models developed to estimate E. coli bacteria concentrations at USGS station 01472157 French Creek near Phoenixville, PA. Producer Defined sitename USGS station (site) name Producer Defined French Creek near Phoenixville, PA USGS station (site) name Producer defined siteno USGS station (site) number Producer Defined USGS-01472157 Agency-USGS station (site) identification number Producer defined datetime Date and local time of sample collection or measurement in either Eastern Standard Time or Eastern Daylight Time Producer Defined 4/18/2019 09:15 9/26/2024 11:45 m/d/yyyy hh:mm JD Julian day (of calendar year) Producer Defined 107 292 1 day Q Stream discharge (instantaneous) Producer Defined 15 323 cubic feet per second temp_degC Water temperature Producer Defined 10.8 27.2 degrees Celsius (deg C) SC_uscm Specific conductance Producer Defined 105 322 microsiemens per centimeter (uS/cm) at 25 degrees Celsius DO_mgL Dissolved oxygen concentration Producer Defined 8.3 12.7 milligrams per liter (mg/L) pH pH Producer Defined 6.7 8.9 standard units EC_mpn E. coli (EC) concentration Producer Defined 25 8160 most probable number per 100 milliliters (MPN/100 mL) Turb_fnu Turbidity Producer Defined 0.3 32.0 formazin nephelometric units (fnu) log10EC log10(E. coli concentration) Producer Defined 1.397940009 3.911690159 log10(most probable number per 100 milliliters (MPN/100) log10Turb log10(Turbidity) Producer Defined -0.522878745 1.505149978 log10(formazin nephelometric units,fnu) sin2piD_365 seasonality term sin(2piJD/365) Producer Defined -0.999546162 0.96347 cos2piD_365 seasonality term cos(2piJD/365) Producer Defined -0.999962936 0.309012956 01472157_FrenchCrk_ECdata_2019_2024exclude.csv Comma Separated Value (CSV) file containing concurrent discrete streamflow, water-quality, and bacteria concentration data for 2019-24 that were excluded from regression analysis; excluded data include environmental replicates, selected flagged values that were investigated and removed as outliers, and values qualified as greater than the maximum reporting levels at USGS station 01472157 French Creek near Phoenixville, PA. Producer Defined sitename USGS station (site) name Producer Defined French Creek near Phoenixville, PA USGS station (site) name Producer defined siteno USGS station (site) number Producer Defined USGS-01472157 Agency-USGS station (site) identification number Producer defined datetime Date and local time of sample collection or measurement in either Eastern Standard Time or Eastern Daylight Time Producer Defined 9/3/2019 9:30 7/1/2024 12:01 m/d/yyyy hh:mm JD Julian day (of calendar year) Producer Defined 179 277 1 day Q Stream discharge (instantaneous) Producer Defined 24 323 cubic feet per second temp_degC Water temperature Producer Defined 12.3 25.5 degrees Celsius (deg C) SC_uscm Specific conductance Producer Defined 105 209 microsiemens per centimeter (uS/cm) at 25 degrees Celsius DO_mgL Dissolved oxygen concentration Producer Defined 8.8 10.4 milligrams per liter (mg/L) pH pH Producer Defined 7.0 8.8 standard units Rmk_EC Remark code qualifier for E. coli value Producer Defined << empty cell >> No Data Producer defined > greater than Producer defined EC_mpn E. coli (EC) concentration Producer Defined 84 10500 most probable number per 100 milliliters (MPN/100 mL) Turb_fnu Turbidity Producer Defined 1.2 32.0 formazin nephelometric units (fnu) log10EC log10(E. coli concentration) Producer Defined 1.924279286 4.021189299 log10(most probable number per 100 milliliters, MPN/100 mL) log10Turb log10(Turbidity) Producer Defined 0.079181246 1.505149978 log10(formazin nephelometric units, fnu) sin2piD_365 seasonality term sin(2piJD/365) Producer Defined -0.998435646 0.060215875 cos2piD_365 seasonality term cos(2piJD/365) Producer Defined -0.999962936 0.055912969 Comment Comment for observations excluded from regression dataset Producer Defined Comments for excluded data include: Environmental Replicates, Greater than values, Outliers 01478245_WhiteClay_ECmodel_2019_2024input.csv Comma Separated Value (CSV) file containing discrete streamflow, water-quality, and bacteria concentration data; these 2019-24 data used as input to linear regression models developed to estimate E. coli bacteria concentrations at USGS station 01478245 White Clay Creek near Strickersville, PA. Producer Defined sitename USGS station (site) name Producer Defined White Clay Creek near Strickersville, PA USGS station (site) name Producer defined siteno USGS station (site) number Producer Defined USGS-01478245 Agency-USGS station (site) identification number Producer defined datetime Date and local time of sample collection or measurement in either Eastern Standard Time or Eastern Daylight Time Producer Defined 4/18/2019 11:15 9/26/2024 13:00 m/d/yyyy hh:mm JD Julian day (of calendar year) Producer Defined 107 292 1 day Q Stream discharge (instantaneous) Producer Defined 23 167 cubic feet per second (cfs) temp_degC Water temperature Producer Defined 11.9 29.2 degrees Celsius (deg C) SC_uscm Specific conductance Producer Defined 238 449 microsiemens per centimeter (uS/cm) at 25 degrees Celsius DO_mgL Dissolved oxygen concentration Producer Defined 8.6 13.7 milligrams per liter (mg/L) pH pH Producer Defined 7.43 9.0 standard units EC_mpn E. coli (EC) concentration Producer Defined 24 12000 most probable number per 100 milliliters (MPN/100 mL) Turb_fnu Turbidity Producer Defined 0.1 20.0 formazin nephelometric units (fnu) log10EC log10(E. coli concentration) Producer Defined 1.380211242 4.079181246 log10(most probable number per 100 milliliters (MPN/100) log10Turb log10(Turbidity) Producer Defined -1.0 1.301029996 log10(formazin nephelometric units, fnu) log10SC log10(Specific conductance) Producer Defined 2.376576957 2.652246341 log10(microsiemens per centimeter, uS/cm at 25 deg C) sin2piD_365 seasonality term sin(2piJD/365) Producer Defined -0.999546162 0.963470965 cos2piD_365 seasonality term cos(2piJD/365) Producer Defined -0.999962936 0.309012956 01478245_WhiteClay_ECdata_2019_2024all_comment.csv Comma Separated Value (CSV) file containing concurrent discrete streamflow, water-quality, and bacteria concentration data for 2019-24 that were excluded from regression analysis; excluded data include environmental replicates, selected selected flagged values that were investigated and removed as outliers, and values qualified as greater than the maximum reporting levels at USGS station 01478245 White Clay Creek near Strickersville, PA. Producer Defined sitename USGS station (site) name Producer Defined White Clay Creek near Strickersville, PA USGS station (site) name Producer defined siteno USGS station (site) number Producer Defined USGS-01478245 Agency-USGS station (site) identification number Producer defined datetime measurement in either Eastern Standard Time or Eastern Daylight Time Producer Defined 6/10/2019 10:45 9/13/2013 13:16 m/d/yyyy hh:mm JD Julian day (of calendar year) Producer Defined 149 271 1 day Q Stream discharge (instantaneous) Producer Defined 28 224 cubic feet per second (cfs) temp_degC Water temperature Producer Defined 14.4 24.8 degrees Celsius (deg C) SC_uscm Specific conductance Producer Defined 187 412 microsiemens per centimeter (uS/cm) at 25 degrees Celsius DO_mgL Dissolved oxygen concentration Producer Defined 8.2 12.5 milligrams per liter (mg/L) pH pH Producer Defined 7.6 8.9 standard units Rmk_EC Remark code qualifier for E. coli value Producer Defined << empty cell >> No Data Producer defined > greater than Producer defined EC_mpn E. coli (EC) concentration Producer Defined 76 4840 most probable number per 100 milliliters (MPN/100 mL) Turb_fnu Turbidity Producer Defined 0.2 36.0 formazin nephelometric units (fnu) log10EC log10(E. coli concentration) Producer Defined 1.880813592 3.684845362 og10(most probable number per 100 milliliters, MPN/100 mL) log10Turb log10(Turbidity) Producer Defined -0.698970004 1.556302501 log10(formazin nephelometric units, fnu) log10SC log10(Specific conductance) Producer Defined 2.271841607 2.614897216 log10(microsiemens per centimeter, uS/cm at 25 deg C) sin2piD_365 seasonality term sin(2piJD/365) Producer Defined -0.998879529 0.545242255 cos2piD_365 seasonality term cos(2piJD/365) Producer Defined -0.976937965 -0.047325324 comment Comment for observations excluded from regression dataset Producer Defined Comments for excluded data include: Environmental Replicates, Greater than values, and Outliers Text files Location of sites GEOREFERENCE FOR ECOLI MODELS AT 4 STREAM SITES.txt General description of data for regression model and model archive README FILE_ECOLI_MODELS.txt .csv files Regression model input files 01481000_BrandywineChaddsFord_ECmodel_2019_2024input 01480870_EBrBrandywineDowningtown_ECmodel_2019_2024input 01472157_FrenchCrk_ECmodel_2019_2024input 01478245_WhiteClay_ECmodel_2019_2024input Discrete concurrent data with comments for observations excluded from regression dataset 01481000_BrandywineChaddsFord_ECdata_2019_2024exclude 01480870_EBrBrandywineDowningtown_ECdata_2019_2024exclude 01472157_FrenchCrk_ECdata_2019_2024exclude 01478245_WhiteClay_ECdata_2019_2024exclude files in .pdf format Regression model summary and archive 01481000_BrandywineChaddsFord_logEC_ModelArchiveSummary_2019_2024 01480870_EBrBrandywineDowningtown_logEC_ModelArchiveSummary_2019_2024 01472157_FrenchCrk_logEC_ModelArchiveSummary_2019_2024 01478245_WhiteClay_logEC_ModelArchiveSummary_2019_2024 National Water Information System (NWIS) - http://waterdata.usgs.gov/nwis 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 (ver. 1.2, March 2024): U.S. Geological Survey Scientific Investigations Report 2017–5075, 46 p., https://doi.org/10.3133/sir20175075. Wagner, R.J., Boulger, R.W., Jr., Oblinger, C.J., and Smith, B.A., 2006, Guidelines and standard procedures for continuous water-quality monitors—Station operation, record computation, and data reporting: U.S. Geological Survey Techniques and Methods 1–D3, 51 p. + 8 attachments; accessed April 10, 2006, at http://pubs.water.usgs.gov/tm1d U.S. Geological Survey - ScienceBase mailing address

Mail Stop 302

Denver CO 80225 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/P13RKCJO None 20260515 Lisa A. Senior USGS - Northeast Region Hydrologist mailing and physical

580 Meetinghouse Road

Ambler PA 19002 717-503-2367 lasenior@usgs.gov FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata FGDC-STD-001.1-1999