The Upper Colorado River Basin Compact (1948)

While the Lower Basin States were unable to agree upon an internal division of the Colorado River waters assumed apportioned to the Lower Basin by the Colorado River Compact of 1922, the Upper Basin States were able to agree upon such a division in order that development could be initiated in those States.

On October 11, 1948, the Upper Basin States entered into a Compact which followed the format and was subject to the provisions of the 1922 Colorado River Compact. Article III apportioned to Arizona the consumptive use of 50,000 acre-feet of water annually and to the following States the following percentages of the total quantity available for use each year by the Upper Basin under the Colorado River Compact and remaining after deduction of the use, not to exceed 50,000 acre-feet per annum made in Arizona:

Colorado			51.75 percent
New Mexico			11.25 percent
Utah				23.00 percent
Wyoming				14.00 percent

Article IV provides that in the event curtailment of use of water by the Upper Division States becomes necessary in order that the flow at Lee Ferry shall not be depleted below that required by Article III of the 1922, the extent of curtailment by each State shall be determined by the Commission (established at Article VIII) upon the application of stated principles. Article V established principles governing the application of the loss of water from storage in reservoirs.

Article VI provided that the Commission shall determine the quantity of the consumptive use of water by the inflow-outflow method in terms of manmade depletions of the virgin flow at Lee Ferry, unless a different method of determination is adopted by unanimous action.. This differs from the Lower Basin formula of "diversions less return flows" (see Senate Document No. 8, 81st Congress, 1st Session, January 31, 1949).

Article VIII created an inter-State administrative agency known as the "Upper Colorado River Commission" and enumerated its powers. The Commission is composed of one member from each of the above-named four States and one Commissioner named by the President of the United States.