San Dieguito River Valley ConservancySan Dieguito
River Valley Conservancy

The San Dieguito River Watershed

Volcan Mountain Map

When it rains, the falling water runs downhill off the land into nearby creeks,  rivers, and lakes. If you were to follow a raindrop from the mountains to the  ocean, you would be following the raindrop through a watershed. A watershed  is the area of land and water bodies that collect rainwater. A watershed  includes the mountains, valleys, and flatlands, as well as water flowing above  ground and underground (groundwater) in creeks, rivers, and aquifers. Most  watersheds eventually end at the coast, often at an estuary open to the ocean.  Flowing water connects all of the communities in a watershed, and what  happens upstream affects those living downstream. 

Did you know that you live in a watershed? We all do. Do you know which one  you live in? If you live between Julian and Del Mar you probably live in the San  Dieguito River Watershed. This watershed starts at Volcan Mountain near Julian  and stretches 55 miles through portions of Julian, Wynola, Santa Ysabel,  

Ramona, Poway, Rancho Bernardo, Escondido, Del Dios, Santa Fe Valley,  Rancho Santa Fe, Fairbanks Ranch, San Diego and Del Mar through the San  Dieguito Lagoon to the Pacific Ocean.  

In terms of land area, the majority of the watershed (79.8%) is within the  unincorporated area of San Diego County. The San Dieguito River Watershed is  presently divided into vacant/undeveloped (54%), parks/open space (29 %),  and urban (18%) land uses. Nearly half of the vacant land area is open to future  development, most of which is zoned for residential use. The current watershed  population is approximately 125,000; however, this level is projected increase to  over 210,000 residents by 2020. 

There are several important natural areas within the watershed that sustain a  number of threatened and endangered species. Among these are the 92,000- acre San Dieguito River Park Focused Planning Area, the 150-acre San Dieguito  Lagoon, and five water storage reservoirs including Lake Hodges, Lake  Sutherland, and Lake Poway. This curriculum focuses on the San Dieguito River Watershed; however, the  environmental and water-quality issues found there are pertinent to most  coastal California watersheds. Click on this link to find out information on other  watersheds in San Diego County. Note: See the watershed map below for the  location of these watersheds.