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Colorado River System shall be beneficially applied." The compact divides the Colorado <br />River Basin into two subbasins: the "Upper Basin" and the "Lower Basin," with Lee <br />Ferry as the division point of the river. Lee Ferry, located in Arizona, is a point in the <br />main stem lmile below the mouth of the Paria River. For the purpose of this report, only <br />portions of the Colorado River Basin located in Colorado are considered. Diversions <br />from the system to areas outside its drainage area are considered herein as exports and <br />have not been classified by types of use. <br />Beneficial consumptive use is normally construed to mean the consumption of water <br />brought about by human endeavors. In this report this includes use of water for <br />municipal, industrial, agricultural, power generation, export, recreation, fish and wildlife, <br />and other purposes, along with the associated losses incidental to these uses. <br />The storage of water and water in transit may also act as losses on the system although <br />normally such water is recoverable in time. Qualitatively, what constitutes beneficial <br />consumptive use is fairly well understood; however, an inability to exactly quantify these <br />uses has led to various differences of opinion. The practical necessity of administering <br />the various water rights, apportionment, etc., of the Colorado River has led to definitions <br />of consumptive use or depletions generally in terms of "how it shall be measured." The <br />Upper Colorado River Commission is to determine the apportionment made to each State <br />by "...the inflow-outflow method in terms of manmade depletions of the virgin flow at <br />Lee Ferry..." There is further provision that the measurement method can be changed by <br />unanimous action of the Commission. Nearly all the water exported from the Upper <br />Colorado River System is measured; however, the remaining beneficial consumptive use, <br />for the most part, must be estimated using theoretical methods and techniques. <br />Reservoir evaporation loss is a consumptive use associated with the beneficial use of <br />water for other purposes. The USBR accounts for main stem reservoir evaporation as a <br />separate item for Upper and Lower Basins, and is not determined by the individual states. <br />Methodology and Data Adequacy <br />The procedures described in the Consumptive Uses and Losses Application Report were <br />applied to the western slope of Colorado for the years 1986 through 1990, using the State <br />of Colorado's consumptive use model (StateCU). The StateCU Graphical User Interface <br />was used to execute StateCU and present the narrative and graphical and tabular results <br />included with this report. More detailed supporting information for the analysis <br />performed for this report is available through input and output summaries for each of the <br />simulations for the CRDSS planning river basins (White, Colorado, etc.). This more <br />detailed information from the individual CRDSS planning river basins is available <br />through the StateCU graphical user interface. <br />This report is based almost entirely on data obtained from the ongoing CRDSS project. <br />Quantitative measurements of water use were used wherever available, but the majority <br />of the basin water use was theoretically calculated. The following sections describe these <br />culossapp Page 7 of 24 09/30/1999 <br />