What is a Watershed? Why are Watersheds Important?

A watershed is a land area that channels rainfall and snowmelt to creeks, streams, and rivers, wetlands, lakes, reservoirs, and estuaries and eventually to the ocean. As water moves downstream it collects pollutants from the built and natural environment.  The concentration of pollutants generally increases in the lower reaches of the watershed.

A watershed is also a group of tributary drainage ways that can be assessed and monitored. They are defined by boundaries within which scientists, engineers, planners and regulatory agencies can gage environmental health, identify water pollution sources and predict downstream impacts. Because all things in watersheds are connected and fed by water flow, the greatest concern in watershed health is water quality.

Watersheds ideally function as an integrated biological system; they are a natural network that ensures healthy environmental function. All of the biological processes in watersheds are interconnected including those outside the waterways. Human activities and land uses within a watershed produce pollutants and pathogens, which are washed into the waterways with rainfall or domestic/industrial water use. As a result, the waterways within watersheds become conduits for pollutants and pathogens that affect the entire food web.

It is important to look at water use from a watershed standpoint. It helps define the environmental health of our immediate surroundings; establish a sense of scale and the role that we play in the health of our ecosystems; and recognize that we all live downstream and that everyday activities can affect downstream water quality and the living things that depend on it. Without clean water, living things die.