A watershed is the area—land and water defined by the hilltops and ridges where rain falls and runs to a common water body. Water,
sediments, and other dissolved material in a watershed drain to a common body of water such as a lake, river, or stream.
Everything that happens in a watershed affects water quality:
• Motor oil dumped down a storm drain
• Pesticides and fertilizers from farmlands
• Withdrawals of water for municipal and farm uses
• Sediments from construction projects
• Timber harvest on steep slopes
