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What Is a Watershed?
Watersheds are defined in terms of nature's
boundaries - mountains and valleys.
Technically, a watershed describes an area of land
containing a common set of streams and rivers that all drain into
a single, larger body of water. Topography determines the size and
shape of a watershed, as mountain ridges divide and determine the
flow of water above and below the surface. The Appalachian Mountains,
for example, form the watershed division between east-flowing streams
that feed into the Chesapeake Bay and Atlantic Ocean, and the west-flowing
streams that drain into the Mississippi River.
Just as streams range in size from small creeks to wide rivers,
watersheds too come in many shapes and sizes. In Pennsylvania, the
three major watersheds are the Ohio River, Susquehanna River and
Delaware River basins. These large watersheds are broken down into
104 smaller watersheds.
Even smaller are the 9,867 subwatersheds that make
up the 104 watersheds. A subwatershed typically ranges from one
to 100 square miles in area. Many of Pennsylvania's watersheds have
been altered by human activities, both in quality and quantity.
Traditionally, water quality improvement projects have focused on
specific sources of pollution, such as sewage discharges, or particular
water resources, such as a stream or wetland.
While this approach may be successful in addressing
specific problems, it often fails to address the more subtle and
chronic problems that contribute to a watershed's decline. In fact,
approximately 96 percent of water pollution in Pennsylvania is linked
to non-point sources, like abandoned mines, agricultural and forestry
activities and urban runoff. Because watersheds are defined by natural
hydrology, they represent a logical basis for managing water resources.
With water as the focal point, we gain a more complete understanding
of overall conditions in an area and the factors that affect those
conditions.
The Governor's Award for Watershed Stewardship recognizes
the leadership of individuals and organizations that have taken
the holistic, watershed approach to heart in protecting and enhancing
Pennsylvania's natural resources. Together, we'll keep our waters
flowing cleaner.
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