The Cuyama Valley was formed by a down faulted block that is bordered on the north by the Morales and Whiterock faults and on the south by the South Cuyama and Ozena faults33.  The basin has been filled with continental deposits resulting from the active faults that border the valley to the north and south, and by alluvium deposited by Cuyama River.  These deposits coupled with the semi-arid climate of the region have created a wide distribution of soil (loam) types with varying compositions of sand, silt, and clay.  Older continental deposits and underlying formations in some of parts of the valley have been folded into a large syncline, which dips northwest toward the valley plain37.  The older deposits have little effect on the distribution and subterranean topography of the groundwater basin, however, the alluvial formations have been folded so that the slope of the beds is favorable for the transmission of water from the southeastern part of the valley37.

Aside from the major faults that bound the valley to the north and south, the only faults known to affect the movement of groundwater are two associated with the Graveyard and Turkey Trap ridges that occur in the middle of the valley37.  These faults have uplifted semi-permeable deposits in the north and restrain movement of groundwater percolating through younger permeable deposits from the south and southeast, thus forcing water to the surface37.  Natural springs have been historically noted near the towns of Cuyama and New Cuyama but were reported dry by 197033.

Climate

The climate of the Cuyama Valley is typical of semi-arid valleys of California’s central coast, with average monthly temperatures ranging from 75°F in summer to 40°F in winter months.  Average annual precipitation is less than six inches and occurs primarily in winter and early spring, peaking in February.  Annual rainfall within the basin ranges from six inches at the valley floor to twenty-four inches in the peaks of the Sierra Madre Mountains that form the southeastern boundary of the watershed15.

Vegetation and Wildlife

Situated on the boundary between Santa Barbara and San Luis Obispo Counties, the Cuyama Valley is a region of exceptional ecological diversity35.  Annual grasslands, chaparral and scrub habitats, blue oak woodlands and pinyon-juniper woodlands dominate the area, but rare habitats such as saltbush scrub, alkaline marshes, and riparian forests are also present. Many bird, herptile, and mammal species inhabit the region. Species of note range from the Tule elk (Cervus elaphus nannodes) and the Burrowing owl (Athene cunicularia), to smaller species like the California horned lizard (Phrynosoma coronatum frontale) and the Western spadefoot toad (Spea hammondii). Federally listed and endangered species in the area include the Giant kangaroo rat (Dipodomys ingens), San Joaquin kit fox (Vulpes macrotis mutica), and Blunt-nosed leopard lizard (Gambelia sila)36. Additionally, a number of plant and animal species have been identified as important conservation targets35.