Tijuana Slough
Map SatelliteAbutting Border Field on the north, this slough is considered among the best pure marine sloughs in the State, having a sufficient tidal prism to flush the channels. In the slough there are 109 hectares (270 acres) of tidal salt marsh with the vegetation consisting of cord grass, Spartina foliosa, pickleweed, Salicornia sp., salt grass, Distichlis spicata, among others.
Some 58 hectares (145 acres) of tidal channels and mudflats thread through the area. Various algae are found here, including Cladophora sp., Enteromorpha sp., and sea lettuce, Ulva lactuca.
The remainder of the area includes sand dunes and a beach, with a variety of salt-tolerant plants. Among them is the rare Cordylanthus maritimus which is found at a number of sites in the slough. Inland there is some coastal sage scrub.
A wide variety of animals inhabits the area. Though not a major stop, it is used by migratory waterfowl. Some 173 species have been recorded in the area, including five endangered species, California least tern, Sterna albifrons browni, light-footed clapper rail, Rallus longirostris levipes, California brown pelican, Pelecanus occidentalis californicus, peregrine falcon, Falco peregrinus anatum, and Belding's savannah sparrow, Passerculus sandwichensis beldingi. The secretive and rare black rail, Laterallus jamaicensis coturniculus, may occur here, though it has not been sighted for several years.
At least 26 species of fish are found in the channels, the most common being the California killifish, Fundulus parvipinnis. Other common fish include the topsmelt, Atherinops affinis, arrow goby, Clevelandia ios, and bay pipefish, Syngnathus leptorhynchus.
A wide variety of invertebrates is found in the slough, including eight species of clams ranging in size from the 6-centimeter (2.5-inch) Chione undatella to the 23-centimeter (9-inch) gaper, Tresus nuttalli, with the most abundant being the chiones and purple clam, Sanguinolaria nuttalli. A host of worms, snails, crabs and numerous smaller marine invertebrates occur in channels and marsh areas.
The slough lies at the mouth of the Tijuana River which, at this point, is frequently intermittent.
Integrity: Filling of a portion of the slough has occurred, and a sewage disposal plant and naval air station are adjacent to the area. There is an abandoned gravel pit with access road within the area.
The slough is now fully protected.
Use: Educational, research, observational. The area is frequently used by educational institutions.
Ref: Anon. 1971. Tijuana River Flood Control Project, Draft Environmental Statement. Ocean Science and Engineering, Inc.
McFlwee, W. R. 1970. County of San Diego Coastal Wetlands Inventory; Tijuana Slough. Mimeo. Calif. Dept. of Fish and Game, Sacramento.
December 1975
Inventory of California Natural Areas
Revision © 2009 Steven Louis Hartman