The Quartz Hill Water Treatment Plant was the first plant built by the Agency and is also the location of the Agency Headquarters. The main control room monitors the Quartz Hill Plant and all of the Agency's other treatment and distribution facilities. After the completion of the second expansion in 1989, the Quartz Hill Water Treatment Plant became capable of producing 65 million gallons per day…

The 14 mgd Rosamond Water Treatment Plant was established to support the needs of consumers in southeastern Kern County, an area that includes Rosamond, Mojave, California City, Edwards Air Force Base and Boron. Rosamond Water Treatment Plant is capable of providing water for 60,000 people.

Expansion of the Eastside Water Treatment Plant located between Littlerock and Pearblossom to 10 mgd was completed in late 1988. It can now serve the needs of about 44,000 consumers.

The 4 mgd Acton Water Treatment Plant was completed in 1989. Water is pumped from the plant site near Barrel Springs Road, on Sierra Highway, to Vincent Hill Summit. From there it is pumped into a Los Angeles County Waterworks pipeline for transport to the Acton area. The plant's capacity is sufficient to supply the needs of 17,000 consumers.