WSP05341

• File Number: 8278.100
• Description: Title I - Yuma Desalting Plant
• Basin: Colorado Mainstem
• Date: 12/23/1992
• Author: USDOI/BOR
• Title: Yuma Desalting Plant - Alternatives for the Interim Period
• Water Supply Pro - Doc Type: Publication

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The Bypass Drain was constructed for conveyance of a maximum capacity of
353 cubic feet per second (ft3js) in order to bypass, if necessary, the
maximum WMIDD drainage flow. Check structures and gated wasteways to
the river channel were also provided for maintenance purposes and for
emergency situations.

COACHELLA CANAL LINING

As authorized by section 102(a) of Public Law 93-320, the first 49 miles
of the Coachella Canal were concrete lined in 1982, and it conserves an
estimated 132,000 af of water annually. This temporary supply of water
was originally intended to be used during an interim period to offset
the impact on reservoir storage of providing additional releases, in
lieu of using WMIDD drainage return flow to meet the delivery
requirements of the 1944 Treaty. The temporary supply was intended to
be used during an interim period while the Desalting Plant was under
construction and while water use in the Lower Basin continued to be less
than apportioned supplies.

The Coachella Valley Water District (CVWD) operates and maintains the
new, lined canal. Canal lining costs are to be repaid by the CVWD over
a 40-year period on an interest-free basis. However, the payments are
waived for the interim period when the United States has use of the
conserved water.

PROTECTIVE AND REGULATORY PUMPING UNIT

Section 103(a) of Public Law 93-320 authorized the construction,
operation, and maintenance of the PRPU to manage and conserve
United States ground water for the United States and for delivery to
Mexico. The PRPU is located in a 5-mile-wide zone along the Southerly
International Boundary between Arizona and Mexico. Under the terms of
the 1944 Treaty with Mexico, approximately 140,000 af of Mexico's
1.5 million af entitlement can be delivered at the Southerly
International Boundary near San Luis, Arizona.

The PRPU was developed to intercept part of the ground-water underflow
that moves southward from the Yuma Mesa in the United States into
Mexico. Before the PRPU was constructed, this underflow was increasing
because of ground-water pumping in the Sonora Mesa Well Field,
immediately south of the Southerly International Boundary in Mexico.

Currently, approximately 100,000 af of this amount comes. from wasteways
(drainage flows) in the Yuma Valley of Arizona, and 40,000 af comes from
the PRPU. Because flows from the wasteways have been greater than
anticipated, only 21 of the 35 wells authorized by the 1974 Act have
been installed and are under operation. The wells are connected by a
15.3-mile pipeline and open concrete-lined canal that carries ~ater by
gravity across the Southerly International Land Boundary. If flows from
the wasteways decline, additional wells will have to be installed.

With 35 wells, the PRPU would be capable of producing about 160,000 af
of water per year. Ultimately, approximately 125,000 af of water from

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