Impaired Streams of Chester County

Of the 2,348 miles of streams in Chester County, Pennsylvania Department of Environmental Protection (PADEP) routinely assesses 1,394 stream miles using an EPA-approved assessment methodology to determine if a stream is meeting water quality standards. In the 2016 report, PADEP listed 957 miles of streams in Chester County as impaired which means they do not meet water quality standards. The list of impaired streams, as well as the list of streams assessed that met the water quality standards, are found in the "2016 Pennsylvania Integrated Water Quality Monitoring and Assessment Report."

Streams are impaired due to a variety of sources and causes, such as "agriculture" (source) and "nutrients" (cause) or "urban runoff/storm sewers" (source) with "siltation" (cause). The same stream segment may be impaired by more than one cause and so a stream segment may be listed by PADEP multiple times.

Sediment laden water can often be seen flowing through Chester County streams
Summary by Major Basins
  • Chesapeake Bay and Susquehanna River Tributaries: 93% of their stream miles are impaired,
  • Christina River Basin: 55% impaired
  • Delaware River Tribs: 100% impaired
  • Schuylkill River Tribs: 66% impaired

Resources for 2016 Impaired Waters


To improve the waters of Chester County, it is essential to understand why streams are impaired and where those impaired streams are located. To assist with this, several resources are available here:
  • CCWRA Online Map Gallery (interactive online maps)
    There are online mapping tools which provide information on the impairments that are listed by PADEP for the waters in Chester County. The "Water Resources of Chester County Tabbed Viewer" and the "2016 Impaired Waters View by "Cause" Web Map" are the two good tools to start with, although most of the other tools also allow the user to view impaired waters information.
  • Chester County 2016 Impaired Waters Map series [2016 data] (11x17 .pdf maps)
    This series of pdf maps begins with an overview map of all Chester County streams impacted by all causes of impairments, and includes 14 additional maps showing the locations of streams by each different cause of impairment, as well as other related maps.

Background Information

Additonal Maps and Tables

GIS Coverages