Coachella Project
California

General Description

The existing 123-mile Coachella Canal is a feature of the Coachella Division of the All-American Canal System (see Boulder Canyon Project, All-American Canal System).  The Coachella Canal conveys Colorado River water from the All-American Canal to irrigate 78,530 acres in the Coachella Valley.  The first 86 miles of the waterway are unlined.  The remaining 37 miles are concrete lined.  The Coachella Canal also has six turnouts to serve about 6,500 acres of non-Federal land on Imperial East Mesa, of which about 500 acres have been developed.  Its capacity is 2,500 cubic feet per second at the turnout from the All-American Canal and decreases through successive reaches to 1,300 cubic feet per second at the beginning of the existing lined section.

After the canal´s completion in 1948, seepage losses developed along the 86-mile unlined section.  The initial 49 miles traverse th coarse, sandy soils of Imperial East Mesa where most severe seepage occurs.  At the Coachella Canal turnout, the average annual diversions are 497,800 acre-feet.  Of this amount, an estimated average of 168,470 acre-feet per year has been lost because of canal seepage.

The primary purpose of the unit is to reduce the water losses in the Coachella Canaly by constructing a new concrete-lined canal to replace the initial 49 miles of the existing canal.  It will extend from the turnout on the All-American Canal to mile post 49, where it will rejoin the existing canal just upstream from siphon No. 7.  The water saved by this action will temporarily be used to replace water lost to the Colorado River by bypassing saline water to the Santa Clara Slough.

Plan

The principal feature of the unit will be a new 49-mile concrete-lined canal.  Wate measurements of flow quantities will be made at two Parshall flumes, one at each end of the new canal .  Water quantities will also be measured at each turnout and at all wildlife watering devices.  Other features will consist of five new check drop structures, eight siphons, three irrigation turnouts, and operating roads.  The existing Coachella Canal turnout, railroad bridges, siphon No. 7, and flood protective works will be retained without modification.  All other existing structures on the first 49 miles of the canal will be abandoned, including the unlined section of the canal.

The new canal is designed to accommodate a flow of 1,550 cubic feet per second, a decrease from the capacity of 2,500 cubic feet per second in the existing waterway.

Reduction of Seepage Losses

The estimated average seepage of the existing unlined canal is 141,000 acre-feet per year.  It is projected that this loss would be reduced to 9,000 acre-feet per year after lining, representing an annual savings of 132,000 acre-feet of water.

Acreage Reduction

The initial 49 miles of the Coachella Canal are presently managed and controlled by the Imperial Irrigation District, which provides irrigation water for California´s Imperial Valley from the All-American Canal.  The district also serves a few farms on the Imperial East Mesa, primarily with  water from the Coachella Canal.

In 1948, when the Coachella Canal was first placed into service, it was estimated that the irrigation potenial on the Imperial East Mesa would be approximately 6,500 acres.  Only 500 acres of this land have been developed, with another 500 acres under partial cultivation.

The Congress made a provision in the law authorizing the Colorado River Basin Salinity Control Project approving purchase of private lands on Imperial East Mesa adjacent to the Coachella Canal.  The acquistion of these lands by the Federal Government will be on a nonreimbursable basis and they will be returned to public domain.  By this action, the Imperial Irrigation District was relieved of responsibility to provide these lands with irrigation services.  When the purchase of lands for acreage retirement is complete, the commitment ot agriculture adjacent to the Coachella Canal will not exceed 2,000 acres.

Fish and Wildlife

The reduction in the greenbelt areas and seepage ponds, that will occur as a result of the construction, will cause a loss of habitat units.  Five measures have been recommended for mitigation which will replace 68.5 percent of the losses.

One feature will be to construct 25 watering devices which will consist of drilling wells, windmills, and water storage tanks.  Each windmill would be capable of producing a maximum of 300 gallons of water per hour when operating under optimum conditions.

The California Department of Fish and Game plans to restore Finney Lake.  About 363 acres of land adjacent to  the Salton Sea National Wildlife Refuge will be developed through the construction of dikes, ponds, and marshes.  The existing tile drainage system will be rehabilitated.

Several isolated parcels of land, totaling 2,120 acres, with high wildlife value will be dedicated to public ownership and maintained in their present condition.  The 160-acre Wister Habitat area will be developed by constructing perimeter roads, levees, ponds, and supply ditches to provide marsh habitat suitable for wildlife.

Attendant Facilities

Power transmission lines were constructed from existing power lines.  They provide energy to electric motors used to operate gates and sensory devices located at various control points.

The check gates in the canal have motorized controls with an interface matching 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, as well as remote control sensory equipment that measures the rate of flow through each of the two parshall flumes located at the inlet/outlet transition of the 49mile lined portion of the canal.

Operating agencies

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 123mile length of the canal were assumed by the Coachella Valley Water District.

Development

Investigations

Since the Coachella Canal was first placed into service in 1949, numerous tests, studies, and surveys have been conducted to determine the effectiveness of the waterway and the approximate amount of water lost by seepage along the entire 123mile length. Several official studies and reports have been published.

Benefits

Irrigation

.

Land Areas (1977)

(See Coachella Division, All-American Canal System, Boulder Canyon Project Rehabilitation and Betterment Program.)

Facilities in Operation

Climatic Conditions

Water Supply

(See All-American Canal System.)

Storage Facilities

(See All-American Canal System.)

Carriage Facilities

(See All-American Canal System.)

Coachella Canal

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