San Dieguito Lagoon
Map SatelliteThough reduced in size and highly disturbed, San Dieguito Lagoon supports remarkably high populations of resident and migratory birds.
Fifty-six species of water-associated birds have been observed in the area, with ruddy ducks, Oxyura jamaicensis, coots, Fulica americana, shovelers, Anas clypeata, and northern phalaropes, Lobipes lobatus, being the most common in season. The California least tern, Sterna albifrons browni, has bred here. An additional 47 species of land birds have been recorded in the area.
There is a typical population of mammals and reptiles.
Only five species of fish occur in the lagoon, due to the varying aquatic conditions. No marine molluscs are present, though there are shells indicating their presence in the recent past.
Over half the area is an upland grassland with salt or alkali-tolerant grasses, herbs and shrubs. The channels and saline ponds are fringed with marsh vegetation including pickleweed, Salicornia virginica, alkali heath, Frankenia grandifolia, and salt grass, Distichlis spicata; in the higher elevations this gives way to a community dominated by glasswort, Salicornia subterminalis. There is a brackish marsh in the less saline ponds, characterized by alkali bulrush, Scirpus robustus.
A deep-water embayment until approximately 2,000 B.P., the area lies on Quaternary alluvium. As the opening to the sea is normally blocked – it being opened only occasionally by artificial breaching or by high flood waters – the salinity of the marsh varies.
Integrity: Much of the original marsh has been filled. A race track, exposition grounds, and various commercial developments surround the marsh, and the area is highly disturbed.
Use: Research, educational, observational. Some private.
Ref: Mudie, P. J., et al. 1976. The Natural Resources of San Dieguito and Batiquitos Lagoons. Calif. Dept. of Fish & Game Wetland Series #12, Sacramento, 100 pp. plus appendices.
March 1981
Inventory of California Natural Areas
Revision © 2009 Steven Louis Hartman