Expert Report of D. Randolph Seahom and Exhibits

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• Consumptive Uses and Losses 9 and future water supply for a growing population in a water -short area. As a result of almost continuous studies concerning these problems, adequate production and effluent records are usually available to adequately assess water use. Transbasin Diversions Nearly all the transbasin diversions both out of and into the Upper Colorado River Basin were measured and reported by the Geological Survey, or local water commissioners and users. The remainder were estimated on the basis of past records and capacity of facilities. Due to the high degree of measurement, this area of basin consumptive use is considered to be quite accurately determined. BENEFICIAL CONSUMPTIVE USES AND LOSSES A summary table of the Upper Colorado River Basin total annual water uses, 2001 through 2005, by states is shown on page iv. Water use within the selected reporting areas is discussed below. Upper Colorado River Basin Tributaries Summaries of estimated annual consumptive uses and losses in the Upper Colorado River Basin for each of the reporting years, broken down by State, reporting area, and type of use are shown in tables UC -2` through UC -6. Estimated main stem reservoir evaporation is shown in table UC -1. Technically, these are not all maim stem reservoirs but are reservoirs that participate in the Colorado River Storage Project (CRSP). The Upper Colorado River Commission designates which reservoirs. in the CRSP have evaporation losses charged to the State and which have losses charged to the basin as a whole. Reservoirs listed in table UC -1 are those to be charged to the basin as a whole. These reservoir evaporation losses amount to about 11 percent of all Upper Basin losses. Upper Basin consumptive use varied between 4.7 million and 3.8 million and averaged 4.2 million acre-feet, per year for the reporting period, 2001 through 2004. Agricultural uses accounted for about 67 percent of the total Upper Basin consumptive uses and losses. Variation in consumptive use during the reporting period was largely due to year -to -year changes in climatic conditions. Transbasin exports, the second largest Upper Basin use, on the average accounted for 20 percent of Upper Basin total use, showed year by year variation during the reporting period ranging from a high of 913,700 acre -feet in 2001 to a low of 670,800 acre -feet in 2002. Water uses for thermal electric power generation remained fairly constant, averaging about 166,900 acre -feet per year, which represents about 4 percent of consumptive use in the Upper Basin.