A watershed is a geographic area that drains to a common waterbody.  Rainwater or snowmelt that falls on the landscape either percolates through the soil and becomes groundwater or flows into the many streams that drain to our common waterbody, the Prettyboy Reservoir.

The Prettyboy watershed is the area of land that drains into the Prettyboy Reservoir and as a resident of the Prettyboy watershed, your daily activities impact your nearest stream and eventually the Reservoir, a drinking water source.

The waterway that is closest to where you live identifies your "watershed address." In the Prettyboy Watershed there are many small waterways that flow into three major rivers: the Upper Gunpowder which drains York County and the northwestern part of the region; Graves Run which drains Manchester and leads to the east; and lastly, Georges Creek which drains Hampstead and the southwestern corner of the watershed.