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1- New Mextlb.s analysis of the wate~vailable from the Colorado River system indicates that with a Lee Ferry delivery of 75 maf in each period of ten years there will always be sufficient water available to meet the Mexican Treaty obligation, which is 1.5 maf annually at the InternatioBa1 Boundary, if the Lower Basin apportionment is shorted by the same amount that the Upper Basin apportionment is shorted. We believe that New Mexico's position is shared by the other States of the Upper Division but not by the States of California and Arizona of the Lower Division. As was done inth~aforementioned November, 1963 water supply determination, the Department of the Interior has assumed, for planning purposes, that the Upper Division must deliver .75 maf annually at Lee Ferry to meet the Mexican Treaty obligation in addition to the Article IIIld) obligation, while disclaiming that this assumption is based on its interpretation of the law of the river. The Upper Colorado River Basin Compact divided the 7.5 maf of the consumptive use apportioned to the Upper Basin among the Upper Basin states. It was agreed that Arizona should have 50,000 acre-feet annually and that the balance would be divided among the other four states. New Mexico's share is set at ll~% of that balance. Note that under the Colorado River compacts, Arizona is a part of the Upper Basin but is not a state of the Upper Division. Thus, Arizona does not have an obligation to deliver water at Lee Ferry under either Article III Ie) or Article IIIld). Upper Basin Water Supply The virgin flow of the Colorado at Lee Ferry may be only about 14 million maf annually, or about a million acre-feet short of the 15 maf nominally divisded at Lee Ferry by the Colorado River ~ 3 -