This data release supports the following publication: Senior, Lisa A., 2017, Estimated Fecal Coliform Bacteria Concentrations Using Near Real-Time Water-Quality and Streamflow Data From Five Stream Sites in Chester County, Pennsylvania, 200716: U.S. Geological Survey Scientific-Investigations Report 20175075 (https://doi.org/10.3133/sir20175075). 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 fecal coliform concentrations during MarchOctober 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), and during 2014-16 developed regression equations to estimate fecal coliform concentrations using available near real-time continuous data for periods ending fall 2015. 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. Data files in CSV format include the variables of datetime, stream discharge (in cubic feet per second), water temperature (in degrees Celsius), fecal coliform bacteria concentrations (in colonies per 100 milliliters), turbidity (in FNU), Julian Day, and calculated or transformed variables of log fecal coliform concentrations, log turbidity, sin(Julian Day/365), and cos(Julian Day/365). Data were collected at the 5 stream sites, French Creek at Phoenixville, Pa., White Clay Creek near Strickersville, Pa., East Branch Brandywine Creek below Downingtown, Pa., West Branch Brandywine Creek at Modena, Pa., and Brandywine Creek at Chadds Ford, Pa.