711.1216A/2489
The Department of State to the Mexican Embassy
Memorandum
Proposed Water Treaty
distribution of rio grande waters
The Ambassador of Mexico and representatives of the Department of State have had a number of conversations relating to various phases of the contemplated international water treaty.
The conversations up to the present have dealt mainly with the question of the allocation to Mexico of waters of the Colorado River. Without prejudice to the question just mentioned or its present status, the Department is desirous as soon as possible of undertaking conversations relating to the allocation to the United States of waters of the Río Bravo.76
It is believed that the Mexican Government understands the approximate needs of the United States. Properly to conserve the waters of the Rio Grande below Fort Quitman for the benefit and use of both countries requires storage and diversion works on the main stream located at such points as will best satisfy the requirements for lands to be served. In the lower area of the Rio Grande, the supply from the main Mexican tributaries, the San Juan River with its Azucar Dam storage and the Río Salado, can be best utilized by gravity canals on the Mexican side for the development of the Mexican area. On the United States side, however, storage and diversion should be upstream from these two tributaries and the needs of the United States area can best be served from upstream contributions. This explains the physical impossibility of attempting the [Page 552] equal sharing of the main stream flow at given points in its course. To overcome these difficulties it is proposed to allocate to each country’s ownership and control definite amounts of flow for storage, diversion and in such a manner as will produce the greatest flexibility and independence of use in both nations.
To that end, it is proposed that a series of storage and diversion dams be constructed on the main stream between Fort Quitman and the mouth of the Río Salado, the latter being the lowest point for effective storage for use of waters in the United States. Above points of international storage the United States believes that there should be furnished from Mexican sources a yearly average (to be determined over three-year periods) of 1,000,000 acre feet of water for storage in the international reservoirs and for diversion and use in the United States. No less than 600,000 acre feet a year, however, should be supplied from the designated tributaries. This amount (1,000,000 acre feet), plus the United States’ contributions, would result in suitable allocation to the United States.
In order to permit more tributary control and development in, and by, each country, the United States would be entitled to the sole use of all contributions from its principal tributaries, and Mexico would retain the contributions from its principal tributaries in excess of 1,000,000 acre feet a year. The principal tributaries should be measured, and those to be measured should be specifically enumerated in the treaty.
Increments reaching the main stream from all other sources (such as springs, arroyo flows and other small tributaries difficult of individual measurement) should be divided equally between the two countries, except that where Mexico fails in any three-year period to deliver the stipulated amount of water for American use, the deficiency should be supplied from Mexico’s share of the unmeasured contributions.
In order to make the water available for diversion and use on American lands, Mexico’s annual deliveries of 1,000,000 acre feet should be from tributaries discharging into the main stream above the lowest point of international storage. Water in the river below this point should be divided equally between the two countries. Each nation should maintain at its own expense proper gaging stations on the designated tributaries at or near the points where they discharge into the river, in order that proper credit may be given for the respective contributions. Gaging stations should be jointly maintained on the main river at suitable locations, in order to determine the increments from sources other than measured tributaries. Water passing Fort Quitman, Texas, should be deemed to be a United States tributary contribution.
Provision should be made for the taking of an annual accounting [Page 553] of the water in each reservoir, in order to determine the quantity to the credit of each nation. Losses from evaporation and waste should be charged to each nation in proportion to the amount in storage to the credit of each nation.
Each country should be given the right to use the bed of the river to carry water allocated to it or released from storage for its benefit.
The number, approximate locations and capacities of the international storage and diversion dams should be agreed upon in the treaty, subject to variations with the consent of both Commissioners. The costs should be prorated between the two countries by the Commissioners in proportion to the benefits each country will receive by reason of their construction, taking into account their utility both for flood control and irrigation purposes.
- Rio Grande.↩