Allegheny River Headwaters Watershed Conservation Plan

Allegheny River Headwaters Conservation Plan
Chapter 3. Water Resources
Tributaries form in higher elevations, where groundwater is discharged to the surface. They grow in
size and volume as the water flows to lower elevations, collecting surface runoff and groundwater
discharges, joining other tributaries to form runs, creeks, streams, and rivers.
According to the Pennsylvania Code (1997), streams
are classified as intermittent, ephemeral, or perennial. This
is based on relative position of stream bottom with respect
to the water table. When detailed water table fluctuation
data is unavailable, benthic macroinvertebrate
communities are a good indicator of stream class.
An intermittent stream is a “body of water flowing
in a channel or bed composed of substrates primarily
associated with flowing water, which during periods
of the year is below the water table and obtains its
flow from both surface runoff and groundwater
discharges.”
The Allegheny River in Coudersport,
PA, is a perennial stream that retains its
flow year-round
In an ephemeral stream, “water conveyance lacks
substrates associated with flowing waters and flows
only in direct response to precipitation in the immediate watershed or in response to melting
snowpack and is always above the water table.”
A perennial stream is a “body of water flowing in a channel or bed composed primarily of
substrates associated with flowing water and is capable, in the absence of pollution or other
manmade stream disturbances, of supporting a benthic macroinvertebrate community composed
of two or more recognizable taxonomic groups of organisms upon available substrates in a body
of water or water transport system.” Perennial streams flow year-round because they are always
below the water table.
Larger waterways are impacted by the quality of water in the tributaries and the quality of
groundwater that discharges into them. Alterations to the quality of water, whether natural or man-made,
have an impact on the quality of the stream and anyone who uses it.
Lakes, Ponds, and Reservoirs
Lakes, ponds, and reservoirs are inland bodies of water. Lakes and ponds are very similar, and
classifying them can be challenging because there is no single set of criteria to distinguish them.
Typically, features, such as water clarity, plant growth, and temperature changes between top and bottom
layers, are used to classify these inland bodies of water as lakes or ponds. Lakes are deeper, have more
visible waves, rooted plant growth near the shoreline, and water temperatures that vary with depth. Ponds
are shallow, have rooted plant growth within the water body, and temperatures that do not vary with
depth. Reservoirs are man-made structures, such as dams, that are built across waterways for the purpose
of storing water for public water supply, safety, or recreation. Lakes and ponds tend to form more
naturally and are usually the result of geological events (US EPA, 2007; Spring Creek Aquatic Concepts).
While lakes and ponds do form naturally, some are man-made. Natural lakes are uncommon in
Pennsylvania, except in northwestern and northeastern Pennsylvania where glaciers once covered the
region, leading to the development of glacial lakes. There are no glacial lakes located within the project
area.
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