You may not realize it, but you are always in a watershed. A watershed is nature’s boundary for water. It includes all the land that drains to a single stream, river, lake or body of water. Rainfall and snow melt flow into streams, rivers, wetlands, lakes and eventually to the ocean. Or, the water may travel through the soil to become groundwater.
Watersheds may be as small as just a few acres, or as large as several states. The watershed of the Mississippi River is about 1.2 million square miles and contains thousands of smaller watersheds. These smaller watersheds drain to smaller streams that empty into a larger river like the Ohio River or Missouri River.
These larger rivers then empty into the Mississippi River. The land in a watershed affects how the water flows. If a watershed has lots of hills and mountains, rain runs off quickly. This runoff will reach the stream or body of water soon after the rain falls. If the land in the watershed is mostly flat, rain will runoff more slowly and not reach the stream or body of water as fast. The rain may soak into the soil and become groundwater.
The land in a watershed may be used for many different things. You may find houses and shopping centers. Parks and golf courses may be found. Factories and farms also are common land uses, as are roads. All these uses affect how water flows. They also affect water quality.
Water that is moving across the land may carry trash, soil, chemicals, or other things. These items may be taken to the stream or lake where the runoff goes. This can change the quality of that body of water. The things we do also can change the water quality. If you dump things like oil on the ground, it can wind up in a lake or stream. If your neighbors are doing the same thing, more oil will travel to the lake or stream. Everyone in a watershed can impact water quality.
Do you know what stream, river or lake is closest to your home? To learn more about your watershed, find out where the water in your backyard goes. Visit the Environmental Protection Agency’s Surf Your Watershed to learn more. Remember - we all have a watershed address and can impact water quality.