The San Dieguito Lagoon

The San Dieguito Lagoon is the “gateway” to the San Dieguito River Park. It has  vital importance for the ecology of the region – for birds as a stop on the Pacific  Flyway, as nesting and foraging areas for endangered species, and as a fish  hatchery. The San Dieguito coastal area is also a significant scenic resource for  residents and visitors in Solana Beach, Del Mar, and San Diego. 

The San Dieguito Lagoon was once the largest of the six San Diego coastal  lagoons, and has the largest watershed. The marsh area alone is believed to  have been over 600 acres, while the entire lagoon probably covered 1,000  acres. Over the years, the lagoon was subjected to major filling activities and  lost over half of its marshes as a result of development projects including  Highway 101, Jimmy Durante Boulevard, residential housing, the Del Mar  Fairgrounds and a World War II airport. Two large dams were constructed  upstream on the San Dieguito River, greatly reducing freshwater inflows. The  result of all these activities was year-round closure of the lagoon mouth  beginning in the 1940s. Only large winter floods or bulldozers opened the mouth  periodically. 

Restoration of the San Dieguito coastal wetlands has been a stated goal of the  Cities of Del Mar and San Diego, and the organizers of the San Dieguito River  Park for almost two decades. In 1983, the California Department of Fish and  Game created a tidal basin in a 70-acre area of the southern lagoon funded in  part by a $1.3 million grant from the California Coastal Conservancy. In addition,  the lagoon mouth was reopened, restoring tidal influence, at least temporarily,  to the entire coastal wetland. The ultimate restoration goal, as stated in the San Dieguito Lagoon Resource Enhancement Program (adopted in 1979) and the  San Dieguito River Park Concept Plan (adopted in 1994), is to restore what  remains of the historically significant San Dieguito Lagoon system.