Chester County/U.S. Geological Survey
Cooperative Monitoring Programs
Stream Flow Gages
The U.S. Geological Survey maintains 17 stations to measure the flow of Chester County streams. Surface-water information collected at these streamflow-measurement stations is used for surveillance, planning, design, flood warning, operation and management of dams, in water-related fields such as water supply, flood control, irrigation, bridge and culvert design, wildlife management, pollution abatement, flood-plain management, and water-resources development.
Ground Water Monitoring Network
Chester County has the only county-wide water-level observation-well network in Pennsylvania. Since 1973, water levels have been measured monthly in a network of 21 wells. An additional 7 wells have been added in recent years to provide a more spatially complete network. Monthly drought-warning and drought-emergency water levels (triggers) have been determined statistically for all but three of the wells in the network using methods described by Schreffler (1997). Data from the network are used by Chester County officials and other agencies to make decisions about when to declare drought watches, warnings, and emergencies.
Precipitation Gages
Ten of the stations that the USGS collects data from for stream flows in or near Chester County are also equipped with precipitation gages. These gages provide data in 15-minute increments and these data are available on the Internet within a few hours of being collected.
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Station
#01472000 - Schuylkill River at Pottstown, PA
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Station
#01473000 - Perkiomen Creek at Graterford, PA
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Station
#01473169 - Valley Creek at PA Turnpike Br near Valley Forge
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Station
#01473500 - Schuylkill River at Norristown, PA
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Station
#01478245 - White Clay Creek near Strickersville, PA
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Station
#01480300 - West Branch Brandywine Creek near Honey Brook, PA
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Station
#01480617 - West Branch Brandywine Creek at Modena, PA
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Station
#01480638 - Broad Run at Northbrook, PA
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Station
#01480870 - East Branch Brandywine Creek below Downingtown, PA
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Station
#01481000 - Brandywine Creek at Chadds Ford, PA
Bacteria Monitoring
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. 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.
Surface Water Quality Monitoring
During the spring, summer and fall months, surface-water quality is monitored at multiple sites in Chester County, including sites on the West Branch Brandywine Creek at Modena (USGS 01480617), on the East Branch Brandywine Creek below Downingtown (USGS 01480870), and on the Brandywine Creek at Chadds Ford (USGS 01481000). Temperature, pH, specific conductance (related to dissolved solids), and dissolved oxygen are measured hourly, and fecal coliform bacteria are measured biweekly. These data are used to assess stream health and to determine trends and detect problems in stream-water quality.
Biological Monitoring Program
Since 1969, the U.S. Geological Survey and the Chester County Water Resources Authority have conducted a cooperative program to evaluate stream ecology and water-quality conditions using benthic macroinvertebrates and stream-water chemistry. The Stream Conditions of Chester County Program has sampled streams every fall for over 30 years. The current goals of the program are to use the data to monitor current conditions and determine trends.
