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Water imported from the Central Valley Project plays a key role in providing local homes and businesses with clean, healthy, and reliable water while also supporting a vibrant agricultural economy. This often-overlooked water source has been a critical component of the San Benito County Water District’s (District) strategy for managing the County’s water resources. It improves the quality of water delivered to residents and farms and ensures that groundwater storage levels remain adequate even during times of drought.
Historically, groundwater was the primary source of water for both municipal and agricultural use in the County. Prior to the importation of water from the Central Valley Project, the local groundwater basin had been in a state of critical overdraft for several decades, meaning that more water was being pumped out than could be naturally replenished. In addition to the declining groundwater levels, the groundwater quality is generally poor and contains high levels of salt and hardness. This required the extensive use of water softeners to make municipal water more palatable, and to reduce damage to household appliances. Water softeners only compounded the problem, because they increased salt loading in the basin and further degraded water quality.
In response to these issues, in 1977 the voters of San Benito County overwhelmingly approved Propositions A and B, which authorized the District to enter into a contract with the federal government for imported water from the Central Valley Project. The propositions also approved the construction, operation, and continued maintenance of the facilities necessary to convey this water to the County and distribute it to District customers.
After nearly ten years of planning and construction, imported water was first delivered to the area in the late 1980’s. It was initially used to restore groundwater levels and to support the District’s agricultural customers. Later, the District began treating imported water and delivering it to municipal customers through the City of Hollister and the Sunnyslope County Water District, which drastically improved the quality of water for household use. It also helped achieve compliance with the State’s wastewater discharge requirements for the City of Hollister’s Wastewater Reclamation Facility, which otherwise would have been prohibitively expensive if imported water was not used as the primary water source.
Since this time, the use of salt-based water softeners has been significantly reduced and salt loading in the basin has decreased. Just as importantly, groundwater levels have recovered to historic highs and the basin is now being managed sustainably. The District has imported over 800,000 acre-feet (AF) of water from the Central Valley Project.
Considering that the local groundwater basin has an estimated usable storage of only 500,000 AF, it is clear that all available groundwater would have been completely depleted if not for imported water.
Water from the Central Valley Project originates as rain and snowmelt in the Sierra Nevada Mountains and is stored in federal reservoirs such as Shasta, Folsom, and San Luis Reservoir. The amount of water the District receives from the U.S. Bureau of Reclamation (Reclamation) each year, varies depending on statewide hydrologic conditions and regulatory requirements intended to protect water quality and sensitive fish species in the Sacramento-San Joaquin River Delta. Reclamation typically announces its initial allocation of imported water supplies in late February and provides regular updates as the rainy season progresses.
Dana Jacobson
General Manager
San Benito County Water District