477. Memorandum From the President’s Assistant for National Security Affairs (Kissinger) to President Nixon1 2

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  • Echeverria Visit and the Colorado River Salinity Problem

The single most important unresolved problem in U.S.-Mexican relations concerns the high salinity of Colorado River waters as they flow into Mexico. If we can find a solution, it will guarantee that President Echeverria’s visit in June will be highly successful. I think it will be possible to hammer out an understanding on this knotty, long-standing problem.


We have had a Water Treaty with Mexico since 1944. It guarantees a fixed quantity of “usable” water from the Colorado. There were no real problems until 1961 when the salinity of the Colorado began to rise sharply. The principal cause was the opening of the Wellton-Mohawk Irrigation project in southern Arizona. The highly saline water from the project drains into the Colorado. The result is that the Mexicans have been getting water significantly worse than that going to U.S. farmers across the border. This has been a bitter issue for farmers in the Mexicali Valley for some years, and they have been putting heat on their Government and their Congress.

A four-year agreement was worked out in 1965 that was satisfactory to both sides. In 1969, a new agreement was reached that was acceptable to the then-President Diaz Ordaz. But at the last minute, he declined to sign on grounds that he did not want to commit his successor, Echeverria, to any agreement on such a sensitive issue.

After fruitless negotiations with the new Administration in Mexico City, we agreed in 1970 to a one-year extension of the old agreement. In 1971, we agreed again to a one-year extension. It is clear that the Mexicans will not, politically cannot, agree to another extension. We almost had a new agreement last November, but it fell through at the last minute when the Mexicans toughened their demands.

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Current Situation

I have had a frank talk with Mexican Foreign Secretary Rabasa about this complicated matter. I was able to satisfy the Mexicans’ requirements on technical details—quantity of water, length of agreement (4–4 1/2 years), and the quality of water we deliver during the agreement. There is one unresolved issue, and it has a high political component that requires attention.

The Mexicans want us to agree to submit the legal aspects of this problem to some form of international arbitration. The formula they prefer is: we pick one arbitrator (non-American); they pick one (non-Mexican). If the two cannot reach agreement, they together select a third arbitrator to reach a majority decision.

Frankly, our people recognize that our legal position on salinity is weak. The Mexicans would probably win on their principal point—the demand for better water—under adjudication or arbitration. That, in turn, would mean we would have to make a heavy investment (new wells, channels, etc.) to provide the quality of water Mexico demands (i.e., as good as U.S. farmers get). It would also unquestionably mean submission of a large damage claim by Mexico (for lost or lower quality crops, etc.). The best available estimate is that this would run in the neighborhood of $85 million.

The problem this raises for us is two-fold: the crash effort to get better water for Mexico would be costly; it would also lower the water reserves of our own Basin States (especially Arizona and California).

I explained to Rabasa that this was a poor time to bring on this kind of political explosion among the people and politicians in seven of our western states. He understood, and backed away from his demand that we agree to an arbitration formula in the context of a joint communique during the Echeverria visit. However, he explained that the issue was just as explosive politically for his President and that they could not simply drop the matter.

His proposal was this: we would put some general language into the June agreement or communique regarding our intention to enter into bilateral “legal talks aimed at a solution;” however, we would have a private understanding that we would go into arbitration early next year.

It seems clear that unless we propose something that gives Echeverria ammunition to cope with this problem among his own special interests groups, we risk forcing Mexico into some less-than-desirable unilateral action—such as going to the World Court. My reading is that if they had agreement on arbitration, they would agree that the arbitrators would not be required to bring in a finding until near the end of the 4-year agreement.

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Reference to judicial decision or arbitration raises some tough problems for us in the Basin States. But I believe that anything less than the above will deeply exacerbate our relations with Mexico.

A Possible Long-Range Solution

There is one possibility that could take us off the horns of this dilemma. Scientists and the Interior Department are convinced they have a technique for de-salting water that would give both our own users and the Mexicans significantly better water in a few years. They want to put a pilot plant near the end of the Colorado River (mainly to de-salt the outflow from the Wellton-Mohawk project), with four other plants to follow. The first plant would be operational in 1975, the second by the end of 1976, and so on. Estimated cost over 8 years: $93 million for five plants; $50 million for related facilities (storage, brine disposal, etc.). This project, together with a long-range plan for control of salinity at the sources of the Colorado, will give our farmers and ranchers much better water. It would also give Mexico what she wants, above all: a definitive solution to the Colorado water problem.

My guess is that this would be attractive enough to convince them to shelve the idea of arbitration altogether. An announcement during the Echeverria visit would, of course, make it an historic event. It would be a dramatic proposal linking modern science with farming, ecology, and a difficult foreign policy problem.

The above raises two operational questions you will wish to consider:

1. Can we offer to enter into bilateral legal talks immediately and give private assurance that we will enter into some kind of arbitration procedure in early 1973?

2. Shall we do detailed staffing of the scientific plan for improving Colorado River water—including more precise costing, Congressional reactions, and expected advantages to our own country, especially in the Colorado Basin States?

  1. Source: National Archives, Nixon Presidential Materials, NSC Files, Box 788, Country Files, Latin America, Mexico, Vol. III, 1972. Secret; Sensitive. Sent for action; Outside system. There is no indication of the President’s action. In a memorandum to Kissinger, June 7, Hewitt indicated that the May 6 memorandum was still with the President. (Ibid.)
  2. Kissinger provided background on the salinity issue and suggested a long-range solution that would obviate the need for arbitration.