IDENTIFICATION OF POTENTIAL SOURCES, MODE OF TRANSPORT, AND STORAGE PROPERTIES OF E. COLI, ENTEROCOCCUS, AND FECAL COLIFORM BACTERIA IN THE WEST BRANCH BRANDYWINE CREEK, CHESTER COUNTY, PENNSYLVANIA

This project is being done in cooperation with the Chester County Water Resources Authority and the Chester County Health Department.

NEED FOR THE PROJECT
The watershed of the West Branch Brandywine Creek in Chester County, Pennsylvania, which covers an area of approximately 135 square miles, is an important source of drinking water and serves a large role in recreational activities for the region. A previous study of this watershed (Bacteria in the Brandywine Creek Watershed ) identified levels of fecal coliform bacteria that exceed the established regulatory criteria set by the US Environmental Protection Agency under various flow conditions. Potential sources, mode of transport, and storage relations of bacteria throughout the fluvial system remain to be identified. Baseflow and stormflow sampling of E. coli, Enterococcus, and fecal coliform bacteria, along with the spatial relationships of sampling locations, and water-quality parameters, will increase the knowledge of potential sources of bacteria and the storage and transport methods within the fluvial system. By determining the potential sources, mode of transport, and storage relations of the fecal coliform bacteria, managers will be able to efficiently prioritize remedial action within the watershed.

Common sources of bacteria within the watershed could include humans, domestic animals, wildlife, and(or) remobilized bacteria stored in fluvial sediments. Environmental and(or) biological factors present within the watershed may cause sudden die off and(or) colonization of these bacteria at any point along the stream reach. Bacteria also may be deposited, colonize, and(or) remain dormant within fluvial sediments for long periods of time. As fluvial sediments are transported during periods of high flow, the bacteria within the sediment are transported as well. This results in the fluvial sediment becoming a source of bacterial contamination and accounts for a portion of the elevated levels of bacteria often seen during high flows. However, because of the various life cycles bacteria may exhibit during transport through the fluvial system, such as die-off, establishing a "mass balance" for bacteria is generally not possible in that bacteria populations may be larger upstream than downstream.

PROJECT OBJECTIVES

1. Identify potential sources of bacteria in a selected reach of the West Branch Brandywine Creek.
   
2. Gain a better understanding of bacteria transport and storage within the fluvial system of the West Branch Brandywine Creek.
   

• Identify sampling locations based on new reconnaissance and unpublished historic data on an urban stream reach through Coatesville, Pa. starting upstream near Pennsylvania State Route 340, continuing downstream past USGS streamflow-measurement station 01480500 (West Branch Brandywine at Coatesville, Pa.), and ending downstream near USGS streamflow-measurement station 01480617 (West Branch Brandywine near Modena, Pa.), approximately 5 stream miles.
  
• Reconnoiter the selected reach and identify specific sampling locations.
  
• Describe the watershed upstream from and alongside the reach by utilizing several geographic information system (GIS) coverages that may include, but are not limited to, primary land use, soils, geology, and(or) outfalls.
  
  
• Identify 75 baseflow-sampling sites and 15 stormwater-sampling sites within the reach and document each site with a global positioning system (GPS) and photograph with a digital camera.
  
• Each of the 75 baseflow-sampling sites will be sampled once for E. coli, Enterococcus, and fecal coliform bacteria, in both sediment and water. Each of the 15 stormflow-sampling sites will be sampled for E. coli, Enterococcus, and fecal coliform bacteria, in water only, at least once, and possibly, twice. Stormflow sampling locations may be revised based on the findings of the first storm event. Priority during storm sampling will be given to "running pipes," storm sewers, and(or) significant tributaries.
  
  
  
• Stormflow for this study will be defined as a peak above baseflow from a precipitation event. This event must be of sufficient magnitude (greater than 0.5 inches of rain widespread over the entire watershed) to ensure that the predominate origin of water into the fluvial system is from overland flow or of sufficient magnitude to elevate the stage throughout the study reach to that of the bankfull discharge. Precipitation will be monitored via precipitation gages at USGS streamflow-measurement stations 01480300 (West Branch Brandywine Creek near Honey Brook, Pa.) and 01480617.
  
• Time, temperature, specific conductance, pH, and turbidity will be recorded at each site during sampling to assist in interpretation of bacteria data.
  
• Streamflow will be measured by standard USGS discharge measurements at a minimum of five locations along the study reach during baseflow sampling and as possible during each storm-sampling event. Streamflow at the time each sample is collected also will be recorded from USGS streamflow-measurement stations 01480300, 001480500, and 01480617, which bracket the study reach. Streamflow data will be used to assist in identification of bacteria sources as well as interpretation of bacteria data.
  
• Baseflow samples will be collected and processed from each site. Baseflow sampling will occur during late June and(or) early July 2003. In-stream samples will be collected from the water column and from bed sediment. Bed sediment will be sampled from the finest material present at the specific sampling location.Outflow samples will be collected directly from the flow if possible (for example, at the mouth of the pipe), and sediment will be sampled at the nearest depositional environment downstream on the same stream bank. Outflow samples that cannot be collected directly at the source will be sampled downstream as close to the source as possible.
  
  
• Stormflow samples will be collected and processed for E. coli, Enterococcus, and Fecal Coliform bacteria from each site. A grab sample will be collected from the water column or directly from the outfall at all sites that are accessible. Priority will be given to "running pipes," storm sewers, and(or) significant tributaries. Stormflow is likely to be turbid and suspended sediments within the water column are assumed to be a combination of both remobilized sediment previously stored within the fluvial system and fresh sediment from overland flow and erosion.
  
  
• The total number of sample locations that may be used for this study is derived from the maximum number of sites that can be processed by the Chester County Health Department laboratory. This maximum number is currently 15 sites per day.
  

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