Expert Report of D. Randolph Seahom and Exhibits

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F Consumptive Uses and Losses TERMINOLOGY The Colorado River is not only one of the most highly controlled rivers in the world, but is also one of the most institutionally encompassed. A multitude of legal documents, known collectively as the "Law of the River," effect and dictate its management and operation. Major documents include: Colorado River Compact - -1922 Boulder Canyon Project Act - -1928 California Limitation Act - -1929 California Seven Party Agreement --1931 Mexican Water Treaty - -1944 Upper Colorado River Basin Compact - -1948 Colorado River Storage Project Act - -1956 United States Supreme Court Decree in Arizona vs California -1964 Colorado River Basin Project Act - -1968 Minute 242 of the International Boundary and Water Commission,' United States and Mexico - -1973 Colorado River Basin Salinity Control Act -- 1974, amended 1984, 1995, and 1996 The Colorado River System is defined in the Colorado River Compact of 1922 as "...that portion of the Colorado River and its tributaries within the United States, ", whereas the Colorado River Basin is defined as "...all of the drainage area of the Colorado River System and all other territory within the United States of America to which waters of the Colorado River System shall be beneficially applied. ". The compact divided the Colorado River Basin into two subbasins- -the "Upper Basin" and the "Lower Basin," with Lee Ferry as the division point on the river. Lee Ferry, located in Arizona, is a point in the main stem 1 mile below the mouth of the Paria River. For the purpose of this report, the Great Divide Basin, a closed basin. in Wyoming, and the White River, also a closed basin, in Nevada have not been considered as part of the Colorado River System since flows from these basins never reach the Colorado River. Diversions from the system to areas outside its drainage area are considered herein as exports and have not been classified by types of use. Beneficial consumptive use is normally construed to mean the consumption of water brought about by human endeavors and in this report includes use of water for municipal, industrial, agricultural, power generation, export, recreation, fish and wildlife, and other purposes, along with the associated losses incidental to these uses. The storage of water and water in transit may also act as losses on the system although normally such water is recoverable in time. Qualitatively, what constitutes beneficial consumptive use is fairly well understood; however, an inability to exactly quantify these uses has led to various differences of opinion. The practical necessity of administering the various water rights, apportionments, etc., of the Colorado River has led to definitions of consumptive use or depletions generally in terms of "how it shall be measured." The Upper Colorado River Basin Compact provides that the Upper Colorado River Commission is to determine the apportionment made to each State by "...the inflow- outflow method in terms 0 of manmade depletions of the virgin flow at Lee Ferry... ".