WSP04323

• File Number: 8271.300
• Description: Colorado River Basin Salinity Control Program - General Information and Publications-Reports
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 4/2/1982
• Author: Raphael Moses
• Title: Hard Water Makes Hard Law - Water Quality Modifications to the Law of the Colorado River
• Water Supply Pro - Doc Type: Report/Study

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After extensive negotiations, an agreement was signed in

February 1944 covering the Colorado and Tijuana Rivers and the

Rio Grande. The most important provision of the treaty with

respect to the Colorado River is the allotment to ~exico of a

guaranteed annual quantity of 1.5 million acre-feet a year. The

State Department defended this agreement by stating that up to

750,000 acre-feet a year would come from irrigation return flows

below Imperial Dam and would probably go to Mexico irrespective

of any treaty. Another State Department argument for the treaty

was that the amount guaranteed to Mexico was less than its

Colorado River use in 1943, which was estimated by the State

Department to be 1.8 million acre-feet.

California made a major issue of water quality during the

Senate hearings. Senator Downey of California questioned the

usability of the supply going to Mexico if the State Department

estimates of return irrigation flows were correct. He made a

remarkably accurate prediction in 1945 by stating that-because

of the ambiguity in the treaty concerning water quality, ~exico

would come back in 25 or 30 years and demand better quality

water. The State Department representatives, their consultants,

and Senate supporters denied there was any ambiguity in the

treaty.

They stated that water quality was extensively discussed

and that Mexico fully understood that the treaty required them

to take irrigation return flows, irrespective of the salinity of

those return flows.

In response to a question at the hearings

before the Senate Foreign Relations Committee, the State Department

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