What is a watershed?
A watershed is an area of land that drains into a particular body of water. Anything happening within that watershed affects the quality and quantity of water in that water body.
The Natural Water Cycle and Watersheds:
While we live on a blue planet, clean, available freshwater is extremely limited! Freshwater is continually cycling (aka the water cycle). When it rains, fresh water collects on the lands surfaces and filters through the soil and into the ground by a process called infiltration. Water is stored underground as groundwater. It is used by plants or flows beneath the surface until it is disposed into rivers and streams and then eventually the ocean. Natural infiltration leads to a high water table and plenty of water flowing in streams during dry weather.
What happens when we build over the natural ground and streams?
When we build over our streams and the ground surrounding the streams, the slow infiltration of water into the ground cannot occur, and instead rainwater gets collected from parking lots and buildings into gutters and pipes that empty all of the water into the stream at once. This does one of two things.
Reduced natural infiltration leads to a lower water table and lower surface flow in streams during dry weather
Trash, pollution and chemicals that are found on the roads flow into the streams and the outcome is poor water quality in the Watersheds