460. Memorandum From Arnold Nachmanoff of the National Security Council Staff to the President’s Assistant for National Security Affairs (Kissinger)1 2

[Page 1]


  • Colorado River Salinity Problem with Mexico

The President indicated to you that he wants to remove remaining irritants in our relations with Mexico. I talked to the Mexican Ambassador who said the only serious problem of concern to his government is that of reaching an agreement on the salinity of lower Colorado River water delivered to Mexico. State has sent you a memorandum on the problem (Tab A), which is a very difficult one to resolve because of strong domestic political constraints.

In essence, if we attempt to meet Mexico’s current demands we would have to deplete the water table in Arizona and neighboring states—an action that would be bitterly opposed by all political forces in those states. The Federal Government could try unilaterally to provide more good water to Mexico, but opposition in the Southwest states would:

  • (a) be a major domestic political cost to the President; and
  • (b) make it virtually impossible to obtain Congressional appropriations for new pumping equipment required to increase the flow of good water to Mexico.

Following is a summary of the background of this problem, the US and Mexican positions, and the current State/Interior approach.


Under a 1944 treaty, the US is obliged to deliver annually to Mexico 1.5 million acre-feet of water from the Colorado River. Since 1961 we have been delivering water of a high level of salinity due to the use of water from the Wellton-Mohawk drainage project (in Arizona) which has a high saline content. Mexico has complained bitterly about the quality of the water. In 1965 we, therefore, concluded a five-year agreement with Mexico in which we agreed to replace 50,000 acre-feet of the Wellton-Mohawk water with water from the Yuma-Mesa resources in Arizona (of [Page 2] much lower salinity). Mexico, to further reduce the salinity of its water, voluntarily decided to bypass an additional 50,000 acre-feet of water per year from the Wellton-Mohawk. However, the Mexican Government wants the full amount of water it is entitled to under the treaty, and, therefore, requested that renewal of the agreement in 1970 include provisions for replacing the bypassed water.


In July 1970 we proposed a new five-year agreement which would meet the Mexican request. We offered to replace an additional 50,000 acre-feet of saline Wellton-Mohawk water with Yuma-Mesa water. This would provide Mexico with the full 1.5 million acre-feet of water per year and improve the quality of the water received.

The July proposal was acceptable to the Diaz Ordaz Administration, which decided, however, to leave the decision to the incoming Administration. The Echeverria Administration has made a counterproposal requesting much more. (It is not clear whether this relatively extreme new position reflects Echeverria’s view or an attempt by his inexperienced and relatively heavy-handed Foreign Minister to achieve a personal success.)


The Mexican proposal calls for replacement of the full 220,000 acre-feet of water from the Wellton-Mohawk area with water from the Yuma resources. Meeting this counterproposal would present virtually insurmountable technical and political problems for us.

Technically, it would require the construction of new wells and pumps in the Yuma area and the need to enlarge the conveyor channel carrying the water to the Colorado River (at a cost of $10–20 million). It would also result in the depletion of about 120,000 acre-feet per year of the State of Arizona’s water resources.

Politically, the President would face very strong opposition from the Colorado River basin states and their representatives on the Hill, such as Senators Goldwater and Fannin. This would make it very difficult if not impossible to obtain Congressional support for appropriation of the $10–20 million required for expanded facilities.

[Page 3]


There are three basic options available to the US for seeking a practical settlement of this problem with Mexico:

  • 1. Inform Mexico we are unable to accept its counterproposal and urge it to reconsider our July proposal.
  • 2. Accept the Mexican counter-proposal. (State believes this is politically unfeasible.)
  • 3. Offer a compromise proposal. This would require additional consultations with the states and the Congress to push to the limits of political acceptability. State and Interior are developing a proposal which would offer to replace during the first year of the agreement 80,000 acre-feet (30,000 acre-feet more than our July proposal) of saline Wellton-Mohawk water with Yuma Mesa water. The amount of Yuma-Mesa water used would gradually decrease over five years as the quality of the Wellton-Mohawk water gradually improves. The proposal would necessitate the appropriation by Congress of $400,000–600,000 for new wells and pumps.

State and Interior plan to pursue Option 1 initially while consulting Congress on the possibility of making a compromise proposal (Option 3) as a fallback position should the Mexican Government again reject our July proposal. We would then offer the Mexicans Option 3 if expected domestic opposition had been overcome and we had assurances from Congress of the necessary funds for construction of facilities. State and Interior believe that if we offer Option 3 now, the Mexicans will take it as a further negotiating position.


It seems to me that the salinity issue is not as susceptible to a quick solution as was the border settlement. The President cannot direct the bureaucracy to concede to most of Mexico’s demands (as he did in the boundary case) because the domestic political stakes and constraints are much higher. The only feasible options appear to be to (a) assure that the fallback position in fact goes as close to the limits of domestic political acceptability as possible, and (b) that we move to the fallback position faster than State and Interior recommend. However, I suggest that before any action is taken, you meet with the Mexican Ambassador to hear his concern, and ask him to reassure President Echeverria that:

[Page 4]
  • —The President wishes to maintain the best possible relations with Mexico and wants to resolve the salinity problem in an equitable way.
  • —We are giving very careful attention to the Mexican counter-proposal. Our preliminary judgment is that it probably will not be possible to meet the Mexican demands because of the very real domestic political restraints which exist. However, the matter will be handled as expeditiously as possible and we will be as responsive as is technically and politically feasible in light of the constraints on Executive power, which you are sure President Echeverria will understand.

Following your conversation with the Mexican Ambassador, you can then issue a directive to State and Interior indicating the President’s strong desire to resolve this problem as expeditiously as possible, and his desire to adopt as forthcoming a position as would be acceptable to the southwestern states and the Congress. I suggest that you not issue the directive until you have talked to the Mexican Ambassador, however, to assure that we are on the right track.


That you authorize me to invite the Mexican Ambassador to meet with you later this week or early next week to discuss the salinity problem.

  1. Source: National Archives, Nixon Presidential Materials, NSC Files, Box 787, Country Files, Latin America, Mexico, Vol. II, January 1, 1970–December 31, 1971. Confidential. Sent for action. The memorandum was sent through Alexander Haig. Kissinger approved the recommendation on April 16. Attached but not published at Tab A is an April 12 memorandum from Eliot to Kissinger, detailing the Colorado River salinity problem. (Ibid.) Kissinger met with Ambassador Olloqui on April 21. During the meeting, Kissinger noted that it would probably be impossible to cede to Mexico’s demands on the salinity issue, and hoped that Mexico would reconsider the U.S. July 1970 proposal. (Ibid.)
  2. Nachmanoff provided background on the Colorado River salinity problem with Mexico. He recommended that Kissinger meet with the Mexican Ambassador to discuss the issue.