WSP07460

• File Number: 8278.400
• Description: Title I - Mexican Treaty
• Basin: Colorado Mainstem
• Date: 2/1/1963
• Author: USDOI/BOR
• Title: Special Studies - Delivery of Water to Mexico
• Water Supply Pro - Doc Type: Publication

Title I Program
Colorado River Basin Salinity Control Act

For example, one result of the WMIDD
irrigation drainage reduction program was
to reduce the volume of the YDP reject
stream from about 40,000 to about
29,500 acre-feet per year by reducing the
volume of the irrigation drainage, The
installed capacity of the YDP was
subsequently reduced from 96 MGD to
72.4 MGD. Therefore, the reject stream
volume has been permanently reduced
by 25 percent,

Ongoing Replacement Water Studies

Currently, Reclamation is studying ways to
increase YDP efficiencies to further reduce
the volume of the reject stream. These
studies are an integral part of the YDP cost
reduction program discussed in chapter IV.
The new membrane technologies program
would contribute most directly toward
increased efficiencies.

To obtain a source of replacement water for
the YDP reject stream, Reclamation is
investigating a proposal to remove riparian
salt cedar along the lower Colorado River
and replace it with vegetation with lower
water demands, This plan would reduce
nonbeneficial consumptive water use along
the river while simultaneously improving
wildlife habitat and recreation values,

Studies of this proposal are being conducted
in two phases. Phase I was initiated in
June 1989, and a draft report was com-
pleted in June 1990, The report
documented existing conditions and the
factors affecting salt cedar removal and
revegetation and included sample feasibility
analysis plans.

Phase II has three objectives: (1) to develop
a 20-year revegetation management plan,
(2) to develop a financial analysis testing
the feasibility of using the saved water to
replace the reject stream, and (3) to develop
a management structure to implement a

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management plan. The 20-year manage-
ment plan will be developed by initiating a
programmatic environmental assessment!
environmental impact statement (EAlEIS),
Coordination with the lower Basin States
will continue to ensure their acceptance and
support. (Also see figure 5,)

"

Preliminary studies indicate that water
savings of 1.0 to 1.5 acre-feet per acre are
possible. To replace 29,500 acre-feet per
year of reject stream, about 20,000 acres of
salt cedar would need to be replaced.

As a fiscal year 1994 planning start,
Reclamation is also investigating a proposal
to create storage on the lower Colorado
River to capture water ordered, but not
diverted, and regulatory waste that would
otherwise be lost to Mexico as excess
deliveries. Preliminary work is currently
funded with Environmental and
Interagency Coordination Activities and
Yuma Area Projects operation and
maintenance funds, The source of funding
for future work has not yet been determined.

Supporting the Primary
Objective in the Future
Without the YDP

No permanent approach to complying with
the obligations of Minute No. 242, other
than operating the YDP, is under active
consideration, If the YDP is not operated,
Reclamation would continue to bypass all
WMlDD irrigation drainage and substitute
water from upstream storage for treaty
deliveries to Mexico, After the United
States loses use of the water conserved by
lining the Coachella Canal, it will have a
significantly reduced ability to replace this
bypass. Should the United States secure
water to replace the reject stream, that
amount of water would be available to
replace bypassed WMIDD irrigation