"Nearly all of the potable water delivered by Calleguas to its member purveyors is purchased from Metropolitan Water District of Southern California. Lying at the northwest tip of Metropolitan’s service area, Calleguas receives from Metropolitan water brought south by the State Water Project and treated at the Jensen Treatment Plant in Granada Hills. (See History for more details.) Water from northern California contains less salt and other minerals than water imported from the Colorado River.
Water from Metropolitan that is not immediately distributed to purveyors is stored either at 10,000 acre-foot Lake Bard located at the District’s hub in Thousand Oaks or at the District’s Las Posas Aquifer Storage and Recovery Well Field . When water is drawn from the lake it is treated once more at the Lake Bard Water Filtration Plant. Water pumped from the Las Posas Basin is treated at the well field before entering the Calleguas system.
Calleguas’ activities extend beyond the distribution of imported water. The District is active in regional water planning, conservation, watershed protection and development of reclaimed water. In an effort to make the water supply of Ventura County more dependable, building the Salinity Management Pipeline to make practical the treatment and use of local groundwater sources would not otherwise be suitable for potable use. Calleguas operates three small distribution systems providing recycled wastewater for irrigation use.