Lake Cachuma: Our Largest Water Supply Source

Cachuma Photo 750 pix

Under normal conditions, the majority of the District water supply is from the Cachuma Project, which the United States Bureau of Reclamation constructed on the Santa Ynez River in the early 1950s.  Lake Cachuma provides about 85 percent of the water for the 250,000 residents and 12,000 acres of agriculture along the South Coast of Santa Barbara County.  Supplies from Cachuma are also released for downstream water rights and federal fish protection requirements.  The District is entitled to 36 percent, or 9,322 AFY, of the Lake yield, which provides for approximately three-quarters of District customer demand in normal years.  

Due to the drought, beginning October 1, 2015 the District has been told by the United States Bureau of Reclamation to expect no new water from the lake.  Instead, the District will carefully conserve stored water left in the lake from previous years, and offset reductions through use of the drought buffer stored in the Goleta Groundwater Basin. Currently the District has seven wells online, which are capable of producing 5.5 MGD.  Over the next 3 years the District intends to invest heavily to expand the production capacity of the wells to make use of this critical local water source and to ensure the long term sustainability of its groundwater basin.

Cachuma supplies are delivered to the Goleta Valley through the Tecolote Tunnel and the South Coast Conduit and treated at the District Corona Del Mar Water Treatment Plant.  Using Cachuma supplies to meet the majority of District demand keeps customer costs low as Cachuma is the most inexpensive source of water available to the District. 

Cachuma Project Facilities

The Cachuma Project consists of Bradbury Dam, Tecolote Tunnel, South Coast Conduit, and various water conveyance facilities.

  • Bradbury Dam: Bradbury Dam is a earthfill structure, containing 6,695,000 cubic yards of material, and standing 279 feet high.  The dam impounds up to 205,000 acre feet of water along the Santa Ynez River, approximately 45 miles from the river outlet at the ocean.
  • Tecolote Tunnel: Water is diverted from Lake Cachuma to the South Coast through the Tecolote Tunnel, which was bored approximately 6.4 miles through the Santa Ynez Mountains to the head works of the South Coast Conduit at Glen Annie Reservoir.
  • South Coast Conduit Pipeline and Reservoirs: The South Coast Conduit extends for a distance of approximately 24 miles along the South Coast from Goleta to Carpinteria, and includes four regulating reservoirs. The South Coast Conduit delivers Cachuma Project raw water to the District at the Corona del Mar Treatment Plant.  The Conduit also delivers water to the other South Coast Cachuma Member Units: City of Santa Barbara, Montecito Water District, and Carpinteria Valley Water District.