Best Management Practices (or BMPs)

Good housekeeping practices that include the proper handling, storage and disposal of toxic materials to prevent storm water pollution.

Catch Basin

Curbside opening that collects rainwater from streets and serves as an entry point to the storm drain system.

First Flush

The first big rain after an extended dry period (usually the summer) which flushes out accumulated pollutants in the storm drain system and carries them straight to the ocean.

Flood Control Channel

The open portion (often concrete-lined) of the storm drain system. Examples include Ballona Creek and the Los Angeles River.


The edge of a street (below the curb) designed to drain water runoff from streets, driveways, parking lots, etc. into catch basins.

Household Hazardous Waste

Common every day products that people use in and around their homes, including paint, paint thinner, herbicides and pesticides that, due to their chemical nature, can be hazardous if not properly disposed.

Illegal Discharge

Any disposal into the storm drain system for which a person or business does not have a permit.

Illicit Connection

Any connection to a storm drain that is not permitted or any legitimate connection that is used for illegal discharge.

Non-Point Source Pollution

Pollution that does not come from a single, identifiable source – includes materials that wash from roofs, streets, yards, driveways, sidewalks and other land areas. Collectively, this is the largest source of storm water pollution.


A flow of water from one drainage system into a larger system, or into a body of water like a river, bay or the ocean.

Point Source Pollution

Pollution from a single identifiable source such as a factory or a sewage-treatment plant. Most of this pollution is highly regulated at the state and local levels.

Source Control

An action to prevent pollution where it originates.

Storm Drain System

A vast network of underground pipes and open channels designed for flood control, which discharges directly into the ocean.

Storm Water

Rainwater that enters the storm drain system and empties into lakes, rivers or the ocean.

Storm Water Pollution

Water from rain irrigation, garden hoses or other activities that picks up pollutants (cigarette butts, trash, automotive fluids, used oil, paint, fertilizers and pesticides, lawn and garden clippings and pet waste) from streets, parking lots, driveways and yards and carries them through the storm drain system and straight to the ocean.


An area of land that drains water or runoff to a single point. For example, the water of the Los Angeles River would be the surrounding neighborhoods and natural terrain.