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District Description
DISTRIBUTION SYSTEM
Westlands is in the San Luis Unit of the CVP. The main water supply features of the Unit are completed and fully operational, including the Delta-Mendota Canal, the San Luis Dam and Reservoir, the San Luis Canal (SLC), and the Coalinga Canal (CC). However, relift pump stations on 12 percent of Westlands' laterals proposed for completion are yet to be constructed. These laterals and relift stations will be a major part of any future Westlands' Distribution System Completion Project.
Also, Westlands operates and maintains the 12-mile concrete-lined CC and the Pleasant Valley Pumping Plant which have a capacity of 1,100 cubic-feet per second.
District Facilities
Westlands' permanent distribution system consists of a closed, buried pipeline network designed to convey irrigation water to 160- or 320-acre land units from the SLC, the CC, and a 7.4-mile unlined canal from the Mendota Pool. The distribution system was built between 1965 and 1979. The area served by the completed system serves approximately 88 percent of the irrigable land in the District, including all land lying east of the SLC. Water is distributed through 1,034 miles of buried pipe, varying in diameter from 10 to 96 inches. Gravity and pumps feed 38 lateral pipelines from the east bank of the SLC, while water is pumped into 27 laterals on the west bank. Six partially completed laterals are served from the CC.
The basic design flow rate of each on-farm delivery system is one cubic-foot per second per 80 acres. The water is delivered with a minimum head pressure of five feet above the high point of the parcel. Farmers control individual deliveries at each of the more than 3,000 metered outlet valves.
Most of the land in the original Westlands is east of the SLC and slopes gently from an elevation of about 320 feet to about 160 to 200 feet at the eastern boundary. Most of this land has gravity service from the SLC. Small recirculating pumping plants at the headworks of each of the gravity laterals pressurize the laterals serving lands adjacent to the SLC which are too high in elevation to be served through the gravity laterals.
The land lying west of the SLC, most of which is in Priority Area II, is at higher elevations than the SLC. It is served by pumping from the SLC and also by gravity from the CC.
Most of the remaining District lands are served by farmer-constructed temporary diversions. The farmers maintain these facilities for Westlands. Some of the pumping costs are offset by the availability of less expensive CVP power.
Approximately one-third of the land between the SLC and the CC is served by pumping from the SLC. The other two-thirds is served by laterals from the CC.