San Antonio Creek is a stream that flows westerly from the Solomon Hills

Solomon Hills

The Solomon Hills are a low mountain range in the western Transverse Ranges, in northern Santa Barbara County, California.The Hills separate the Santa Maria Valley and Santa Maria to the north, from the Los Alamos Valley and Orcutt to the south.-History:...

 through the Los Alamos Valley, the Barka Slough and the San Antonio Valley on its way to the Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, north of Purisima Point. It passes through the town of Los Alamos, California

Los Alamos, California

Los Alamos is a census-designated place in Santa Barbara County, California, United States. Although located in the Los Alamos Valley, the town of Los Alamos is usually considered to be a part of the Santa Ynez Valley community...

 and then Vandenberg Air Force Base

Vandenberg Air Force Base

Vandenberg Air Force Base is a United States Air Force Base, located approximately northwest of Lompoc, California. It is under the jurisdiction of the 30th Space Wing, Air Force Space Command ....

 in Santa Barbara County, California

Santa Barbara County, California

Santa Barbara County is a county located in the southern portion of the U.S. state of California, on the Pacific coast. As of 2010 the county had a population of 423,895. The county seat is Santa Barbara and the largest city is Santa Maria.-History:...

.

Watershed

The creek originates about ten miles east of Los Alamos. The lower reaches throughout Vandenberg AFB have a perennial flow, in part because of irrigation tailwater, but primarily because of a geologic rift at Barka Slough which causes an upwelling. The principal crops grown are vegetables in the flat areas, and winegrapes in the transitional uplands. All are irrigated from groundwater resources. In 1996 almost all of the water supply for Vandenberg AFB was taken from the San Antonio aquifer. 36% of the San Antonio Creek Hydrological Unit is within Vandenberg Air Force Base.

Ecology

West of Barca Slough, San Antonio Creek is inhabited by the endangered Unarmored Three-spined stickleback

Three-spined stickleback

The three-spined stickleback, Gasterosteus aculeatus, is a fish native to much of northern Europe, northern Asia and North America. It has been introduced into parts of southern and central Europe.-Distribution and morphological variation:...

 (Gasterosteus aculeatus williamsoni) which, for all practical purposes, prohibits any stream maintenance. The endangered Tidewater goby

Tidewater goby

The tidewater goby Eucyclogobius newberryi is a goby native to lagoons of streams along the coast of California.-Taxonomy:The genus name translates as "true cycloid goby", referring to the scales, while the species epithet is in honor of J. S. Newberry. The tidewater goby is the sole member of its...

 (Eucyclogobius newberryi) is also found in the creek's brackish coastal lagoon and several miles upstream in sections of stream impounded by California Golden beavers (Castor canadensis subauratus) which provide ideal slow-moving water habitat for gobies.

San Antonio Creek from Rancho del las Flores Bridge at State Highway 135 to the Railroad Bridge downstream, impaired for boron, ammonia, and nitrite.