Hollister Urban Area Water Project (HUAWP), California

The Hollister Urban Area Water Project is being developed in San Benito County, California, US. Image courtesy of Hollister Water Improvement Project.

Upgradation works on the Lessalt Water Treatment Plant were completed in January 2015. Image courtesy of Hollister Water Improvement Project.

Filters at the Lessalt Water Treatment Plant (WTP). Image courtesy of Hollister Water Improvement Project.

West Hills water treatment plant treats the water supplied from the San Justo Reservoir. Image courtesy of Hollister Water Improvement Project.

The Hollister Urban Area Water Project (HUAWP) in San Benito County, California, US, is part of a series of water projects under the Hollister Urban Area Water and Wastewater Master Plan, which aims to increase the quality and quantity of water supplied to the area, including the City of Hollister and nearby unincorporated areas of San Benito County.

A memorandum of understanding (MoU) has been signed by the City of Hollister, the San Benito County Water District and the Sunnyslope County Water District (SSCWD) to begin works on the master plan. The collaborative effort provides advantage of shared resources and economies of scale.

The HUAWP proposes to increase the surface water supply to local residents and businesses by building the new West Hills Water Treatment Plant and expanding the capacity of the Lessalt Treatment plant.

The total investment on the HUAWP is estimated to be $30m. San Benito County Water District (SBCWD) will provide $10m while the remaining cost will be borne by the water-consuming public of the City of Hollister and the Sunnyslope County Water District over a 30-year period.

Benefits of HUAWP

Surface water from the San Felipe Project is capable of meeting the water requirements of only a part of the Hollister area. Water pumped from the local groundwater basin has high levels of salts and requires water softeners as a result. The high-level of mineral content in the water supplied to local residents also damages electrical appliances such as dishwashers, water heaters and washing machines.

Improved water treatment will produce high-quality drinking water with low levels of salt for customers in the City of Hollister and the Sunnyslope County Water District, while reducing the dependency on bottled water.

Moreover, the HUAWP will also enhance the treatment capacity of the local wastewater treatment systems to improve the quality of wastewater discharges. This reduces pressure on surface and groundwater supplies. The treated water can be used for irrigational purposes instead of being discharged to water bodies.

Hollister Urban Area Water Project (HUAWP) details

The project will increase the capacity of water treated from the San Luis Reservoir. It includes upgradation of the existing Lessalt Surface Water Treatment Plant located on Fairview Road and construction of a new West Hills Water Treatment Plant near Union Road.

It will also include associated works such as installation of new pipelines for distribution of drinking water to customers throughout the Hollister Urban Area, along with the central and western parts of the city and the Ridgemark area.

Groundwater is currently supplied from the groundwater wells throughout the Hollister area whereas surface water is imported from the Central Valley Project (CVP). Surface water has fewer minerals and other salts as compared to groundwater which is in continuous contact with geologic formations.

Lessalt water treatment plant upgrade

The Lessalt WTP started operations in January 2003 to treat lower salt-content surface water from the CVP San Felipe Division for distribution to the Sunnyslope County Water District and the City of Hollister.

The $6.8m upgrade of the plant was completed in January 2015, providing a capacity to treat two million gallons of water a day (mgd). The Supervisory Control and Data Acquisition (SCADA) system installed in the plant allows SSCWD to supervise and remotely operate the plant through a computer. The treated drinking water from the Lessalt WTP is distributed to customers in Ridgemark, Sunnyslope and the City of Hollister.

West Hills Treatment plant construction

Construction of the West Hills Treatment Plant is proposed to start in 2015. The plant will treat up to 4.5mgd of surface water and has provision for capacity expansion if necessary in future.

It will be located in an unincorporated area of San Benito County bordering the City of Hollister in the hills north of Union Road. It will be built on a 33-acre land jointly owned by the City and SSCWD.

The proposed plant will have an initial treatment capacity of 4.5mgd to 6mgd with an option for expansion to 9mgd.