Bacteria Monitoring Stations in Chester County, Pennsylvania

The Chester County Water Resources Authority, Chester County Health Department and the U.S. Geological Survey are cooperating on a monitoring project to measure fecal coliform bacteria at three sites in the Brandywine Creek watershed (see map).  These three sites are typically sampled approximately once every two weeks during the spring, summer and early fall months when the Brandywine Creek is frequently used for recreation.  

Due to the 24-hour incubation period required for analysis of bacteria in water samples, results from the sampling are typically published on this website within 2 to 3 days of the actual sampling date. The Pennsylvania Department of Environmental Protection 's standard for fecal coliform bacteria in reacreational waters is 200 colonies per 100 milliliters (mL)*.

* - During the swimming season, (May 1 through September 30), the maximum fecal coliform level shall be a geometric mean of 200 colonies per 100 milliliters (ml) based on a minimum of five consecutive samples, each sample collected on different days during a 30-day period. No more than 10% of the total samples taken during a 30-day period may exceed 400 per 100 ml. For the remainder of the year, the maximum fecal coliform level shall be a geometric mean of 2,000 per 100 milliliters (ml) based on a minimum of five consecutive samples collected on different days during a 30-day period. (Commonwealth of Pennsylvania, Pennsylvania Code, Title 25, Chapter 93, Water Quality Standards, December 15, 2001)

Continuous Water-Quality Monitoring Stations in Chester County, Pennsylvania

Streamflow is sampled hourly for basic water-quality parameters such as pH, specific conductance, temperature, dissolved oxygen, and turbidity by automated water-quality monitors. Monitoring streamflow is an important part of protecting and maintaining surface-water supplies and aquatic habitats. Water resource authorities and county health departments use these data to monitor for threats to surface-water supplies and fish. If dissolved oxygen drops below 5 milligrams per liter, which may occur in the warmer months, fish kills could result. Data from the stream-water-quality monitors also are used to:

• monitor water quality for biota and human health,
• monitor the effects of reservoir releases, short- and long-term effects of urbanization,
• support designations of "High Quality Watershed" or "Exceptional Value Watershed"