Watershed - Watershed is the term used to describe the geographic area of land that drains water to an ocean or bay outlet. The watershed includes the geographic area surrounding the stream system that captures precipitation, filters and stores water, and generates runoff into the stream system. The stream system is the visible, aboveground portion of a larger drainage system. A watershed, therefore, is an area of land that drains water, sediment, and dissolved materials to a common outlet.
Any activity that changes soil permeability, vegetation type or cover, water quality, quantity, or rate of flow at a location can change the characteristics of a stream or even the watershed at downstream locations. Land use practices such as clearing land for timber or agriculture, developing and maintaining roads, housing developments, and water diversions may have environmental consequences that greatly affect stream conditions even when the land use is not directly associated with a stream. Proper planning and adequate care in implementing projects can help ensure that one activity within a watershed does not detrimentally impact the downstream environment.
In recent years, watersheds across the United States have become a focal point for community-based environmental conservation. Through the collaborative efforts of watershed groups – consisting of the people living and working within each watershed – major improvements in water quality, fisheries enhancement, wildlife habitat, and overall quality of life have been accomplished. A watershed provides water for drinking, recreation, and agriculture, and is a rich source of biological diversity that includes habitat for many threatened and endangered species, including salmon and trout.