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<br />IH)1089 <br /> <br />Colorado River Depletions <br />February 25, 2000 <br />Page 2 of2 <br /> <br />The Colorado River Water Conservation District (Attachment 2) by contrast did a <br />linear regression or trend line analysis using Reclamation's consumptive uses and losses <br />data that showed Colorado reaching full compact development by about 2020 using the <br />same 6,000,000 acre-foot hydrologic determination. This is also a valid approach, <br />However, as the River District notes, a number of factors affect annual depletions and <br />future water development opportunities, This is illustrated by the relatively low R2 value <br />for the 1971-1995 trend analysis. The R2value can be improved by eliminating outliers <br />and using other data smoothing techniques. <br /> <br />Finally, using Colorado's Decision Support System (CDSS), we did an <br />independent analysis of Colorado's consumptive use of Colorado River water to compare <br />with Reclamation's calculations. That analysis showed that CDSS can more precisely <br />estimate shortages based on actual water supply available to various facilities, which <br />results in less consumptive use. Also, we were able to evaluate the incidental losses <br />calculated by Reclamation. The evaluation of incidental loss values developed by <br />Reclamation we believe is high and can not be fully justified, We intend to work with <br />Reclamation to develop a better procedure for dealing with incidental losses, The net <br />result of our CDSS work is that we feel Colorado's consumptive uses and losses may be <br />up to 15 percent (approximately 250,000 acre-feet) less on average than reported by <br />Reclamation, <br /> <br />Other Considerations <br /> <br />In addition to having better information and tools to process that information, we <br />need to look at how our water uses are changing. It is no secret that we are losing <br />agricultural lands to urban development and that there is an increasing desire to leave <br />water in the streams for recreational and environmental purposes. Also, we have seen <br />many efforts such as the Colorado River Salinity Control Program implemented to cause <br />us to use our water more efficiently. These factors in my opinion will continue to slow <br />the development of new water resources, <br /> <br />Conclusion <br /> <br />I do not foresee Colorado using up its Colorado River apportionment under the current <br />hydrologic determination before 2050. I believe the increases in consumptive use we <br />have seen over the last 20-25 years will slow. I also feel some of the increases are due to <br />simply doing a better job of collecting and analyzing data, Improvements in data <br />collection will likely continue, but I do not think those improvements will have as <br />significant an effect on the overall result like some have in the past. <br /> <br />Cc: <br />Andy Moore <br />Ray Alvarado <br />Eric Kuhn <br />Scott Balcomb <br />