A watershed is a land area that funnels rainfall or snowmelt to a watercourse or larger body of water.
![River bed at dusk](/sites/default/files/styles/1024_x_601/public/2022-05/pexels-donald-tong-105170.jpg?itok=qv_GkggZ)
A watershed can be minute in scale, consisting of just a small lake or a single county. However, some watersheds extend for thousands of square miles and can include streams, rivers, lakes, reservoirs, and underlying groundwater.
When rain falls, it can soak into the ground or may run off the surface. Water that seeps into the soil will eventually make its way into the nearest stream. Some water infiltrates much deeper, into underground reservoirs called aquifers. In areas where the soil contains hard clay, very little water may infiltrate the ground. Instead, it quickly flows to lower ground.
Even parking lots, roads, and buildings are part of a watershed. During periods of heavy rain water runs off these impervious surfaces and into storm drains. These storm drains funnel that water into streams and rivers where it can overwhelm them, causing them to overflow and possibly flood.
Every inch of the United States is part of a watershed. In fact, all land drains into a lake, river, stream or other water body and directly affects its quality. Because we all live on the land, we all live in a watershed—thus watershed condition is important to everyone.
Healthy watersheds provide critical services, like clean drinking water, fisheries, and outdoor recreation, which support our economies, environment, and quality of life. The health of clean waters is heavily influenced by the condition of their surrounding watersheds, mainly because pollutants, such as fertilizers, pet waste and insecticides, can wash off from the land to the water and cause substantial harm.
Water picks up pollutants as it flows over land and through hundreds and thousands of creeks and streams. Since this can have negative effects on the ecology of the watershed and, ultimately, on the reservoir, bay, or ocean where it ends up, it’s important that we do our part to protect our watersheds. Here are some tips on how to keep it clean and healthy.