Watersheds

El Capitan Watershed and Reservoir

A watershed is an area of land that drains water into a lake or river. Everything that is on the land, whether a natural feature or a human activity, is part of the watershed. Each of us lives, works, or plays in watersheds.

Reservoirs are more commonly known as lakes. In the San Diego region, all reservoirs (lakes) are man-made features built to supply water to our communities. The Water Department operates nine water supply reservoirs throughout San Diego County. These reservoirs capture runoff from rainfall and also store water imported from hundreds of miles away. Our reservoirs are critical components of the regional water supply system as water is supplied to nearly 2 million people in the City of San Diego and neighboring communities.

Otay Dam and Reservoir

Protecting water sources is vital to providing healthy and safe drinking water to all of our customers. We have a commitment to environmental protection because our watersheds and reservoirs have multiple uses such as drinking water, irrigation, recreation, wildlife food and shelter. What we do in our everyday lives can have an effect on watersheds, reservoirs, and the quality of our drinking water.

Watershed Map (PDF: 1.3Mb)
Watershed Sign Program

Our Drinking Water, Our Watersheds, Our Responsibility Display Board (PDF: 1.5Mb)
Learn about how the Water Department protects our watersheds and how you can help prevent pollution and contaminants from getting into our drinking water.

Source Water Protection Guidelines
These Guidelines are aimed at protecting our local source waters from the effects of new residential and commercial development in the watersheds.

How Your Pesticides and Herbicides Can Affect Water Quality (PDF: 550k)
A guide about limiting contamination by keeping pesticides, herbicides, and irrigation runoff out of our waterways and source waters.