FAQs

What is stormwater?

Stormwater is water that originates during precipitation events. Stormwater that does not soak into the ground becomes surface runoff, which either flows directly into surface waterways or is channeled into storm drains , which eventually discharge to surface waters.
What is a watershed?

A watershed is the area of land where water collects and drains into a specific river, ocean, lake, or other body of water. For example, the Los Angeles River watershed includes all of the land draining into all the streams, creeks, and rivers that flow into the Los Angeles River and ultimately out to the Pacific Ocean. Watersheds vary in size from the largest rivers, such as the Mississippi River to the small creeks which can have a watershed of an acre or more.
What watersheds are in Los Angeles County?

There are six major watersheds in Los Angeles County which are primarily served by the Los Angeles Flood Control District. It encompasses more than 3,000 square miles, 85 cities, and approximately 2.1 million land parcels.
Where do pollutants come from?

Most storm water pollution comes from everyday people doing everyday activities such as drive our cars, take care of our homes and lawns, and walk our dogs. We may be contributing to stormwater pollution even without realizing it. After a rain shower, all the dirt and debris that was on the land is picked up by the storm water and gets washed into the storm drain system.
What is a TMDL?

A Total Maximum Daily Load (TMDL) is a regulatory term in the U.S. Clean Water Act, describing a value of the maximum amount of a pollutant that a body of water can receive while still meeting water quality standards. Alternatively, TMDL is an allocation of that water pollutant deemed acceptable to the subject receiving waters. TMDLs have been used extensively by the U.S. EPA and state environmental agencies in implementing the Clean Water Act by establishing maximum pollution limits for dischargers.
What is a BMP?

Best Management Practices (BMP) is a term used to describe a type of water pollution control. Stormwater BMPs can be classified as "structural" (i.e., devices installed or constructed on a site) or "non-structural" (procedures, such as modified landscaping practices).