WSP01908

• File Number: 8278.300
• Description: Title I - Merxican Deliveries
• Basin: Colorado Mainstem
• Date: 2/1/1963
• Author: USDOI/BOR
• Title: Special Studies - Delivery of Water to Mexico
• Water Supply Pro - Doc Type: Publication

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2. future Q;uality of Water Delivered to ~Iexico. The vater
to be delivered to Mexico under Phases 1 and 2 of the proposed
program will not have any deleterious effect on soil productivity
insofar as exchangeable sodium levels are concerned. The sodilDD.
adsorption ratio under Phase 1 will range from 4.7 to 6.5 and from
5.3 to 5.9 under Phase 2. The dissolved mineral content ot vater
delivered to Mexico v1l1 be approximately 2,000 ppm and 1,800 ppm
after construction under Phases 1 and 2, respectively, is completed.
At the present time, the unfavorable salt balance in the Mexical1
Valley is pr1lllar11y due to the lack of adequate leaching of excess
soluble salts from overextension of the cropped area. The situation
in the Mexical1 Valley today vas not brought about by a year of
\lellton-Mohawk drainage operations but, rather, it is the accumulation
of irrigation practices over an extended period of time. The water
available under the treaty is not sufficient to irrigate the present

acreage and maintain the proper salt balance. Even curtai1lIlent of

the present acreage would reqUire that adequate leaching and drainage

be prov1aea~0 prevent waterlogging and surface accumulation of
hs.rmf\U. salt s .
Initially, the total quantity of dissolved solids contained in
Colorado River vater delivered under the proposed plans will remain
approximately the same on an annual basis but v1l1 be reduced as
refreshing of the Wellton-Mohavk aquifer progresses, If Mexico

carries out accepted irrigation and leaChing procedures the salt con-

centrations will not be detrimental to the crops that are presently
being grO\lll. Neither will these concentratiollii of salt be detr1Jllental
to soils in the irrigable classes. A number of irrigated areas in

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