Chapter 1: Summary of "The Law of the River"

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10 UPDATING THE HOOVER DAM DOCUMENTS 2.8 maf /yr plus one -half of any surplus water unapportioned by the Compact, subject to the availability thereof for use in Arizona under the Compact and Project Act. Nevada was accorded the right under Article 7(f) to contract for 1 /25th of any surplus water available in the Lower Basin. The details of these contracts and of the Secretary's contracts with agencies and water users in Arizona and Nevada may be found in Chapter II hereof. F. The Mexican Water Treaty The possibility of a future Treaty with Mexico concerning Colorado River waters was recognized in Article III(c) of the Colorado River Compact of 1922. This provided that any right to the use of such waters accorded Mexico shall be supplied first from surplus over and above the aggregate of the quantities specifiie and P aragraphs I1I(a) and (b), and if insufficient, then the deficiency shall be borne equally by e pp Lower Basins and whenever necessary the States of the Upper Division shall deliver at Lee Ferry water to supply one of deficiency us of 2 maf anonuallydwould dbe available. (Therespecctive obl igations a of the Basins at that time that p under this provision is still subject to different interpretations.) The d thatinoth n n shall be mentioned d as a denia Bouder Canyon Project Act o o recognition of any r ght , if an y, .in Mexico to provided that no g the use of waters of the Colorado River System. In 1922 Mexico used 500,000 acre -feet of Colorado River waters annually. By 1935, when Hoover Dam was finished, Mexico used 750,000 acre -feet annually. By 1944 that use had risen to 1.5 maf annually. Ef- forts to negotiate an agreement with Mexico failed in 1930 when Mexico claimed 4.5 maf and the United States offered 750,000 acre -feet. However, negotiations initiated in 1941 did result in the 1944 Treaty. That Treaty linked the waters of the Rio Grande River (much of whose waters originate in Mexico but is used in the United States) with the Colorado River waters (all of which originates in the United States) . Impetus to a Treaty was provided by the scheduled organizational meeting of the United Nations and by the fact that Mex- ico was a wartime ally of the United States. ntatives from each of the seven Basin States) had proposed The Committee of Fourteen (two represe deliveries to Mexico of 800,000 acre -feet each year the releases from Lake Mead total 10 maf plus a percent- nia age change when Lake Mead releases were moretwo l ess other O Basin States supported i Ca n if � o �der and Nevada opposed the 1.5 maf adopted by the to limit Mexico before her increasing uses invaded their share of Compact water. Article 10 of the Treaty guarantees to Mexico a minimum quantity of 1.5 maf of Colorado River water an- nually, to be delivered in accordance with schedules furnished in advance by Mexico. The need for the schedules was to require Mexico to take minimum flows which comprised leakage from Imperial Dam and return flows below Imperial Dam which could not be controlled in any event. If there is a surplus, as deter- mined by the United States, an additional 200,000 acre -feet may be provided, but Mexico acquires no rights to more than 1.5 maf. Mexican deliveries will be reduced in the same proportion as con- In the event of an extraordinary drought, sumptive uses in the United States are reduced. Even in the drought years of 1976 - this provision was not utilized nor is it settled whether water in storage in United States reservoirs may be protected or must be released to satisfy the Treaty obligation. 2 The question of the quality of the water has been a source of controversy. Article 10 refers to "waters of the r Colorado River, from any and all sources..." Article 11 states that the waters to be delivered shall be made up of the waters of the river, "whatever their origin..." The United States has construed the Treaty to mean that Mexico can be given waters of any'quality; i.e., return flow or seepage, whether usable or not. The Mexican view is that the water has to be usable and of a quality equal to that delivered to the United States users. The Mexican salinity problems are covered in O. of this Chapter I and in Chapter VI hereof. Mexico was required by Article 12 to construct a diversion structure below the upper boundary line, which it did by building Morelos Dam, and protective works to prevent damage to United States lands. The United States was to build a regulating dam which it did by constructing Davis Dam. Article 13 dealt with flood control plans. Article 15 contained schedules of deliveries.