What is a Watershed?

A watershed is the geographic area draining into a river system, ocean or other body of water through a single outlet and includes the receiving waters.  Watersheds are usually bordered and/or separated from other watersheds by mountain ridges or other naturally elevated areas.  In other words, all of the land in Orange County drains to a body of water that ultimately leads to the Pacific Ocean by traveling through the watershed.  Another way to look at it is if you were to cup your hands and someone poured water on your palms, the water would all run to the point where your hands meet – this point simulates a river or creek and your palms the land of a watershed.

The land that drains into the watersheds of Orange County also includes pollutants like litter, cigarette butts, fertilizer, pesticides, pet waste, motor oil or lawn clippings.  All of these types of pollution can be picked up by stormwater or runoff from sprinklers and hoses and carried into streams, rivers or channels and swept out to the Pacific Ocean.

In Orange County, there are 11 watersheds.  We’ve provided a page with more information on each watershed and a map to help you determine in which watershed you live.  The County is divided into three Watershed Management Areas help focus water quality and restoration efforts on the watershed scale.  Watershed Managers and stormwater experts throughout the County work together to prevent water pollution and restore aquatic resources.

Regulations protecting water quality in California are primarily National Pollution Discharge Elimination System (NPDES) permits for stormwater and runoff and Total Maximum Daily Loads (TMDLs) for specific pollutants.  For more information, please visit our pages on the NPDES program and TMDLs.

Remember – The Ocean Begins At Your Front Door.  No matter where you live, you live in a watershed!

What is a Watershed?

“Watershed” may sound like a small building with water in it, but it’s not!

Watershed Brochure