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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As the 1974 Act allows and enV1Slons the use of the conserved water to
assist the Secretary by replacing the additional water released from
storage and does not direct the Secretary to operate the Desalting
Plant, it appears that the Secretary has sufficient discretion to use
the conserved water to continue the storage releases and allow the loss
of irrigation drainage in lieu of operating the Desalting Plant, as long
as California water requests are met.

uncertain Risks to States Water Supply

While it is clear that water belonging to the Basin States is being
allowed to be bypassed and lost, it is not clear that this loss will
cause harm, so long as the river reservoir system refills and all Basin
States needs are met. After the interim period ends, the primary
rationale for not operating the Desalting Plant relates to the Colorado
River reservoir system (reservoir system) storage capacity. The
Colorado River reservoir system has reservoir storage equal to about
four times the annual runoff, allowing the reservoir system to satisfy
water needs through extended periods of drought without imposing
shortages. For example, computer simulation models were used to combine
the recent driest 6-year sequence with the driest 12-year period of
record (1953 to 1964). Beginning with full Colorado River reservoirs,
after simulating the above IS-year sequence, lake Mead was found to have
over 10 million af in carryover storage. (Currently, storage in the
Colorado River reservoir system is at 69 percent of capacity, with over
18 million af of vacant storage space).

Based on the computer ~imulation assumptions mentioned above, operation
of the Desalting Plant may not significantly reduce the likelihood of
Colorado River system shortages. As the Upper Basin has yet to fully
develop, overall water supply demands continue to be less than the long-
term supply. With the large carryover storage of the Colorado River
reservoirs, the probability that shortages will occur in the foreseeable
future is relatively low, and there is a good probability that the
reservoir system will fill, and flood control releases will be required.
If so, water conserved by operation of the Desalting Plant and reserved
in storage may eventually be spilled and may in part be wasted.

Santa Clara Slough Preserved

By not operating the Desalting Plant, WMIDD drainage would continue to
be bypassed, and the Slough would be maintained.

CONS:

loss of Research Capability

By shutting down the Desalting Plant, the Test Plant would no longer be
operational for conducting desalting research, and desalting expertise
within Reclamation would be lost. The opportunity envisioned in
Section 203 (b) of the authorizing Act, to advance water treatment
technology relative to lowering treatment costs and making advance
treatment more practical by operating the Desalting Plant, would be

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