WSP07975

• File Number: 8278.100
• Description: Title I - Yuma Desalting Plant
• Basin: Colorado Mainstem
• Date: 10/1/1987
• Author: USDOI/BOR
• Title: Yuma Desalting Plant Operations Study - Draft Special Report
• Water Supply Pro - Doc Type: Publication

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INTRODUCTION

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~UR~OSE

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This special report documents the identification and evaluation
of proposed plans to reduce the cost of operating the Yuma
Desalting Flant (YDP). It also recommends conducting a more
detailed evaluation of several plans which would provide Mexico
with water of suitable quality.

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The plans recommended for furtheL evaluation were selected by
analy~ing YDP operations, identifying plans that might reduce or
eliminate YDP operation, establishing evaluation criteria, and
rating the proposed plans.

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LOCATION

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The YDP is located 4 mi~es west of Yuma, Arizona, adjacent to the
Colorado River flood plain, and immediately upstream of Mareloa
Darn (see Map No. 1292-300-41.

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The study area is located primarily in the Yuma, Arizona, area,
where the desalting plant is located. However, for some plans
the study area expands to include portions of the Colorado River
drainage system.

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SUMMARY O~ DESALTING ~ROCESS

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The YD~ desalts irrigation return flows pumped from the Wellton-
Mohawk Irrigation and Orainage District (Wellton-Mohawk). In the
desalting process, about 70 percent of the irrigation returns are
desalted into a good quality product flow. The remaining 30
percent, or reject stream, in which the salts are concentrated,
is discharged through the concrete-lined By-pass Drain into the
Santa Clara Slough in Mexico, upstream of the Gulf of California.
The product water from ~he YDP is blended with some irrigation
return flow and is discharged into the Colorado River above
Mareloa Dam for delivery to Mexico. Any excess untreated
irrigation return flow from the Wellton-Mohawk is diverted
directly to the Santa Clara Slough (see map No. 1292-300-4)
When e~cess flows occur on the river, the entire irrigation
return flow is bypassed to the Santa Clara Slough. The ~ederal
Govern~ent is responsible for replacing any water rejected for
the YDf or bypa33ed to the Santa Clara Slough.

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BACKGROUND

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The Colorado River drains an extensive area of the states of
Wyoming, Colo~ado, Utah, Nevada, Arizona, California, and New
Mexico, and ultimately empties into the Gulf of California. The
long-term annual flow, based on a 78-year period from 1906
through 1983, and measured at Lee's Ferry la Colorado River
gaging station located about 1 mile below the mouth of the Paria
River), is about 15 million acre-feet of water. A number of

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