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- CRBSCP - Coachella Canal Unit - Title I
CRBSCP - Coachella Canal Unit - Title I
State: California
Region: Lower Colorado Basin Region
Related Documents
Related Facilities
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BCP - Coachella Canal Rehabilitation and Betterment
Yuma Area Office
General
The Coachella Canal Unit is one of three components authorized under Title I of the Colorado River Basin Salinity Control Act. The other two components are the Desalting Complex Unit and the Protective and Regulatory Pumping Unit, which are discussed in separate brochures. The original 123-mile Coachella Canal was a feature of the Coachella Division of the All-American Canal System, Boulder Canyon Project. The Coachella Canal delivers Colorado River water from the All-American Canal to irrigate 78,530 acres of agricultural land in the Coachella Valley of California. Originally, the first 86 miles of the waterway were unlined, and the remaining 37 miles were concrete lined. The original canal also had six turnouts to serve about 6,500 acres of non-federal land on Imperial East Mesa, of which about 500 acres have been developed. The capacity of the original canal was 2,500 cubic feet per second at the turnout from the All-American Canal where it began, and was decreased through successive reaches to 1,300 cubic feet per second at the beginning of the last 37 miles -- the lined section (terminal end). After the canal`s completion in 1948, seepage losses developed along the 86-mile unlined section. The initial 49 miles of the original 86-mile unlined section traversed the coarse, sand soils of Imperial East Mesa where the most severe seepage occurred. At the canal`s starting point, the turnout from the All-American Canal at Drop No. 1, the average annual diversions were 497,800 acre-feet. Of this amount, an estimated average of 168, 470 acre-feet per year had been lost because of canal seepage. The primary purpose of the Coachella Canal Unit is to reduce the water losses in the Coachella Canal by constructing a new concrete-lined canal to replace the initial 49 miles of the unlined section of the canal. This 49-mile replacement extends from the turnout at Drop No. 1 on the All-American Canal to mile Post 49, where the replacement rejoins the 37-mile unlined section of the original canal just upstream from siphon No. 7. Then, the 37-mile unlined section joins the last 37 miles of canal, the only originally lined section of the canal. The water saved by the new lining will temporarily be used to replace the water which is bypassed to the Santa Clara Slough; the bypassed water is not counted as part of Mexico`s allotment of Colorado River water.
History
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Construction
Construction of the relocated portion of the Coachella Canal, including advance planning and reconstruction activities, required about 3 years. Construction started in 1979, and was completed in 1982. The lining of the first 49 miles of the Coachella Canal will result in direct benefits by saving 132,000 acre-feet of water per year, and a reduction in operation and maintenance costs.
Plan
The plan called for a principal feature of the unit to be a new 49-mile canal which replaced the initial 49 miles of the original 86-mile unlined section. Water measurements of flow quantities are made at two parshall flumes, one at each end of the new canal. Water quantities are also measured at each turnout. Other features consist of four new check drop structures, eight siphons, six irrigation turnouts, and operating roads. The existing Coachella Canal Turnout, siphon No. 7, and flood protective works are retained with only minor modification. All other existing structures on the first 49 miles of the canal have been abandoned, including the replaced unlined section of the canal. The new canal is designed to accommodate a flow of 1,550 cubic feet per second. The estimated average seepage of the originally unlined 49-mile length of canal was 141,000 acre-feet per year. It was projected that this loss would be reduced to 9,000 acre-feet per year after lining was completed, representing an annual savings of 132,000 acre-feet of water When the Coachella Canal was first placed into service in 1948, it was estimated the irrigation potential on Imperial East Mesa would be about 6,500 acres. However, only 500 acres of this land have been developed. Congress made a provision in the law, and authorized the Colorado River Basin Salinity Control Project to approve purchase of private lands on Imperial East Mesa adjacent to the Coachella Canal. The acquisition of these lands by the Federal Government will be at Federal Government expense, and the lands will be returned to public domain. By purchase of these private lands, the Imperial Irrigation District was relieved of responsibility to provide these lands with irrigation services. When the purchase of lands on the Imperial East Mesa for acreage retirement is complete, the commitment of water to agriculture located adjacent to the Coachella Canal will not exceed 2,000 acres. A reduction in greenbelt areas and seepage ponds has occurred as a result of construction of the newly lined section, and has caused a loss of habitat. Five measures were recommended for mitigation: 1. Construct wells with windmills and watering devices for wildlife use. Each windmill is capable of producing 300 gallons of water per hour when operating under optimum conditions. The California Department of Fish and Game is responsible for the operation and maintenance of the windmills with funds provided by the Bureau of Reclamation. 2. Contract with the California Department of Fish and Game to restore fish and wildlife habitat at the Finney-Ramer Wildlife Management Unit. 3. Acquire and develop about 363 acres of additional land adjacent to the Salton Sea National Wildlife Refuge through the construction of dikes, ponds, and marshes. 4. Purchase the Oasis Tract of land which contains high wildlife value, is dedicated to public ownership, and will be maintained in its present condition. 5. Develop and 160-acre Wister Habitat Area by constructing perimeter roads, levees, ponds, and supply ditches to provide marsh habitat suitable for wildlife. Power transmission lines were constructed from existing powerlines. They provide energy to electric motors to operate gates and sensory devices located at control points for regulating and measuring flows. The check gates in the canal have motorized controls which also match the sensory gate opening equipment. This equipment was furnished and installed by the Coachella Valley Water District. Monitoring equipment was installed at all check structures, and remote control sensory equipment measures the rate of flow through each of the two parshall flumes located at the inlet and outlet transition of the 49-mile lined portion of the canal. The entire length of the relocated canal is flanked by two operating roads. A 20-foot-wide gravel surface road, used for operations and maintenance, was constructed along the southwest bank of the new canal; and a 16-foot unsurfaced service road was graded along the northeast bank. Abutments were provided on each side of the canal, about 2,000 feet downstream from the turnout, for a future vehicle bridge to provide access to a proposed recreation area being planned by the Bureau of Land Management. Prior to the new lining, the Imperial Irrigation District operated the first 49 miles of the original canal, and the Coachella Valley Water District operated and maintained the remaining 74 miles. Upon completion of the lining project, the operation and maintenance of the entire 123-mile length of the canal was assumed by the Coachella Valley Water District. Fish and wildlife mitigation measures are operated by fish and wildlife agencies at their expense.
Overview
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Other
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Contact
Contact
Title: Area Office ManagerOrganization: Yuma Area Office
Address: 7301 Calle Agua Salada
City: Yuma, AZ 85364
Phone: 928 343-8100
Contact
Title: Public Affairs OfficerOrganization: Lower Colorado Regional Office
Address: PO Box 61470
City: Boulder City, NV 89006-1470
Fax: 702-293-8333
Phone: 702-293-8000
