What is a watershed
No matter where you live, you live in a watershed.
A watershed is the land area that drains to a single body of water such as a stream, lake, wetland, or estuary. Hills or ridgelines often bound watersheds; interior valleys collect precipitation in streams, rivers, and wetlands. These physical boundaries define the movement of water and delineate the watershed. Watersheds, also known as catchments or basins, describe geography at many different scales: a few acres may drain to a small stream or wetland; a few large rivers may drain into an estuary where fresh and salt water mix; about 40 percent of the U.S. land area in the lower 48 states drains to the Mississippi River. Watersheds are thus "nested" - larger watersheds such as the Mississippi River basin encompass many smaller watersheds.
See the River of Words website for more.
This information was taken from EPA Office of Water publication Protecting and Restoring America's Watersheds, EPA-840-R-00-001.
Pennsylvania is divided into 6 major watersheds: the Ohio, the Genesee, the Susquehanna, the Delaware, the Erie, and the Potomac. These watersheds drain large portions of the state into major waterways such as the Chesapeake Bay, Lake Erie and the Ohio river.
See the PA Environmental Council's treatment of What is a Watershed?
Each of these watersheds contains thousands of smaller watersheds. As the size of the waterway decreases, the drainage area decreases. When considering rehabilitating a watershed, try to choose a small enough area to be manageable such as 50,000 acres or less. To find out what watershed you live in visit: