WSP11122

• File Number: 8271.300
• Description: Colorado River Basin Salinity Control Program - General Information and Publications-Reports
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/3000
• Title: OPINION - Colorado River Salinity Problem - Submitted to His Excellency - Honorable Antonio Carillo Flores - Ambassador of Mexico
• Water Supply Pro - Doc Type: Report/Study

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39

ing credit to the United States for groundwatcrs artifi-
cially introduced into the river which materially affects
the quality of delivered water and which is harmful for use
in irrigation seems to conflict with such correspondence.

Additionally, the preamble to the treaty recites that the
general purpose in concluding the treaty was" to obtain the
most complete and satisfactory utilization" of the waters of
these international streams. Delivery as treaty water of
highly saline groundwater which increases the level of
salinity of waters delivered to Mexico so as to be harmful
for irrigation purposes appears to conflict with the purpose
set forth in the preamble.

To summarize, Article 10 of the treaty grants to Mexico
an annual allocation of 1,500,000 acre-feet of the waters of
the Colorado River. This grant is limited by two phrases,
one indicating that the waters may be "from any and all
sourees" and a second indicating that the waters shall be
made up of the waters of the said river "whatever their
origin." Testimony g'iven during Senate hearings indi-
cates that the parties intended that the purpose of these
phrases was to allow the United States to receive credit
for return flow waters. Accordingly, it appears to us that
Mexico may not complain if the delivery of return flow '
waters deteriorates the waters of the Colorado River. On
the other hand, it appears to us that groundwaters such as
those discharged from the Wellton-Mohawk division are
not contemplated by the term" return flow," as defined in
the treaty, and that such groundwaters should not be con-
sidered to be "waters of the Colorado River" for which
the United States should receive credit." We think this

U9 The United States panel which participated in tho 1962 sturly of the
salinity problem divided Welltoll-Molmwk groull(lwatcr into that containing
g'reater concentrations of dissolved solids and that with lesser concentrations,
recommending that the fonner be delivered to a point below Morelos Dam and
that tho latter bo delivered to the boundary to be credited against the treaty
obligation. With rogard to the latter, the panel stated that the annual
amount to be thus conveyed "should equal the deep percolation from irriga-

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