Conservation Priority Watersheds


Multiple aspects of stream and watershed conditions were used to rank all small watersheds in Pennsylvania according to water quality, aquatic habitat quality, and biological diversity. Three types of information were employed to determine Pennsylvania’s Conservation Priority Watersheds:

•       The ACC biological community information provides a way to examine watersheds based on stream habitat types and the organisms that occur within them. Those communities which are of the highest-quality demonstrate where the most intact aquatic habitat exists.

•       Biological metric calculations provide a way to quantitatively rank streams and watersheds on habitat and water quality. Both fish and macroinvertebrate data were used to score streams. Streams with high-scoring metrics were used to select the CPWs.

•       High-quality stream reaches, referred to as Least-Disturbed Streams (LDSs), provide examples of the highest quality stream reaches in a given region. They were determined based on ten different data types that represent disturbances such as pollution, hydrologic alteration, stream connectivity, quality of riparian habitat, and information about the surrounding land use. LDSs represent the top 10% of all stream reaches in Pennsylvania; those with the highest water quality and intact habitat. The results of the Least-Disturbed Streams (LDS) analysis were included in the CPW designation by calculating the total number of LDS reaches in each watershed.

Watersheds that scored in the top 10% were categorized as Tier 1 conservation watersheds. Watersheds that scored below Tier 1 but in the top 20% were categorized as Tier 2 conservation watersheds.

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