Stream Designations

Understanding stream labels and designations in Pennsylvania can be complicated. Designations should be taken for what they are – a simple determination at one point in time (though designations may have regulatory impacts). All streams have unique influences, ecosystems, and other factors to consider, so if two streams are both designated as Cold Water Fishes, for example, that does not mean they are in identical condition. Still, these designations offer a good indicator for stream health.

Brown and native Brook Trout (above) typically can only survive year-round in CWF waters.
Brown and native Brook Trout (above) typically can only survive year-round in “Cold Water Fishes” waters. Original photo courtesy of Duane Raver / USFWS

PA Chapter 93 Water Quality Standards

For more information on these standards, click here.

Aquatic Life

There are three primary labels used to describe the aquatic life of Pennsylvania streams- Cold Water Fishes, Warm Water Fishes, and Trout Stocking. These designations rely mainly on the thermal characteristics of the streams. Stream temperature (particularly how hot it gets in the summer) has a tremendous impact on which fish, plants, and macroinvertebrates can survive in the streams. It should be noted that all streams in Blair County are also designated Migratory Fishes which means that these streams allow fish to move from certain waters to complete their life cycle in other waters (such as the American Shad).

Cold Water Fishes sections of streams are often in good condition from an aquatic life perspective. Warm Water Fishes and Trout Stocking streams may be in need of restoration work, increases in riparian buffer coverage, or other stormwater best management practices to help bring the stream temperature down so trout populations can survive and populate in these streams year-round.

Special Protection

Streams of the highest quality are given special protection under Pennsylvania law. Exceptional Value streams are considered the best Cold Water Fishes streams, and High Quality streams are very good Cold Water Fishes streams or the best Warm Water Fishes/Trout Stocking streams. These determinations are based, in part, on stream chemistry, biology, ecology, and surrounding land use.


Pennsylvania Fish and Boat Commission Standards

For more information on these standards, click here.

Class A Wild Trout Streams

Streams that support naturally reproducing populations of wild trout are labeled Class A streams. These streams are not stocked, yet naturally contain trout in sufficient quantities and size to sustain a long-term sport fishery. This designation focuses on sustained populations of the native Brook Trout and the naturalized Brown Trout. The PA Fish and Boat Commission categorizes Class A streams into:

  • Class A Brook Trout
  • Class A Brown Trout
  • Class A Mixed Brook and Brown Trout


303(d) Impaired Streams and TMDLs

For more information on these designations, click here.

Under the Clean Water Act, states are required to monitor their rivers, lakes, and streams and determine which water bodies are not meeting water quality standards. These “impaired and threatened” waters are compiled into a state’s 303(d) list of impaired streams. The states must then take steps to improve water quality so these streams can be removed from the list.

When streams are designated as impaired, this often leads to the development of TMDLs (Total Maximum Daily Load) for impaired streams. A TMDL is essentially a “pollution diet” that sets the maximum amount of a pollutant that may enter a stream for that stream to still meet water quality standards. TMDLs must take into account point sources of pollution (which can be traced to a specific place, such as a wastewater treatment plant) and nonpoint sources (which can’t be traced to a specific place, such as stormwater runoff).

There are three main categories for impairment:

  • Point Source Pollution
  • Nonpoint Source Pollution
  • Abandoned Mine Drainage

There are several types, causes, and sub-categories to the impairment sources:

  • Temperature
  • Excess Nutrients
  • pH
  • Metals
  • Siltation
  • Chlorides
  • Low Dissolved Oxygen
  • Stormwater Runoff
  • Suspended Solids
  • Cause Unknown