WSP01625

• File Number: 8276.854
• Description: Palo Verde Unit - Colorado Salinity River Control Program
• State: CA
• Basin: Colorado Mainstem
• Date: 7/1/1981
• Title: Palo Verde Irrigation District Unit Special Report
• Water Supply Pro - Doc Type: Report/Study

SUMMARY

The PVID (Palo Verde Irrigation District) investigation in southeastern
California was authorized by P.L. 93-320 wherein the Secretary of the Interior
was directed to expedite studies to determine the most cost-effective way to
reduce the salinity concentration in the Colorado River system by reducin9
the quantity of poor quality water entering the Colorado River, Irrigation
return flows from the irrigation district flow into the Colorado River
carrying over 152,000 tons of salt annually from the study area. An increase
in salinity concentration at Imperial Dam of about 19 m9/L (milligrams per
liter) results from both off-farm and onfarm sources. Soil Conservation
Service and Reclamation would coordinate individual efforts in the total
salinity reduction program.

Some of the irrigation facilities in the PVID were constructed
with little overall planning in design and seepage prevention.
system seepage through the unlined canals results in a loss of
loading of the Colorado River.

before 1900
Conveyance
water and salt

A Status Report on the PVID unit was completed in March 1980. That report
indicates a potential for a salinity control project on a portion of the
District and provides preliminary estimates of the cost and effectiveness of
the various alternatives. This Special Report is to inform concerned interests
of the costs and impacts associated with alternatives currently being considered.

Current alternatives being examined include improved irrigation efficiencies
and lining a total of about 20 miles of laterals in Palo Verde subarea which
would reduce the salinity at Imperial Dam by about 7.9 mg/L. The Palo Verde
subarea comprises about 10 percent of the District service area and is the
only area where salinity control activities appear justified.

Total project costs for the Palo Verde subarea are estimated at $24 million
on the basis of January 1981 prices, exclusive of the mitigation plan. This
results in a cost-effectiveness of about $242,000 for each mg/L of salinity
concentration reduction at Imperial Dam making it among the most cost-effective
of the agricultural source control units. The PVID unit cost-effectiveness
also compares very favorably with the cost-effectiveness of proposals for
point and diffuse source units (where desalting and evaporation pond disposal
are anticipated as the expected strategy) that have a cost-effectiveness in
excess of $1.5 million per mg/L at Imperial Dam.

In addition, studies are currently being made to examine the potential for a
ground-water flushing alternative.

The problems and needs of the Irrigation District are such that the District
would benefit, not only from lining portions of their distribution systems as
a part of the salinity control program, but from lining all the canals and
laterals. Lining would provide adequate delivery rates for most efficient
water use, eliminate gopher damage and bank failures, eliminate loss of
water, and reduce operation and maintenance costs for the District. If a
hydroelectric generating facility were installed at the Palo Verde Diversion
Dam pursuant to legislation currently before the Congress, the reduced

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