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<br />001534 <br /> <br />950 <br /> <br />ECOLOGY lA W QUARTERLY <br /> <br />[Vol. 28:903 <br /> <br />volume of floods and other unplanned releases of water that <br />reach the Delta will gradually decline as the Upper Basin <br />continues to develop.293 The EIS acknowledges, however, that <br />under the Basin States Alternative, there will immediately be <br />fewer flood flows south of Morelos Dam, and the volume of any <br />remaining flows will decline. 294 The reasons for these <br />consequences are straightforward. Reservoir drawdowns increase <br />storage, thus allowing for the maximum capture and use of flood <br />flows. Flood releases from Hoover Dam, which only occur under <br />full reservoir conditions, are virtually the only means by which <br />water ever reaches the Delta. Therefore, the more Lake Mead is <br />drawn down, the less likely water will reach. the Delta. Flood <br />flows that would normally pass the dam will be captured during <br />periods of low reservoir levels and later released as "surplus. "295 <br />In conclusion, the new Surplus Criteria create a <br />comprehensive, highly structured allocation system for Colorado <br />River water that is heavily prejudiced against the delivery of <br />excess water to Mexico. As a result, the Surplus Criteria have <br /> <br />293. See FINAL EIS, supra note 180. at 3.16-24. <br />294. The Basin States Alternative will reduce flows south of Morelos Dam by 6% to <br />100% (resulting in an average reduction of 30%) compared to baseline conditions <br />under 75th percentile flow conditions. See Table 3.16-2, FINAL EIS, supra note 71, at <br />3.16-20, and Attachment N: Comparison of Colorado River Flows, N~26 - N-31 (for <br />example, the EIS predicts a reduction in surplus flows from 153,000 af to 0 in 2005 - <br />a 100% reduction - and a reduction from 534,000 af to 500,000 af in 2006 - <br />approximately a 7% reduction). Under 90th percentile flow conditions, by contrast, the <br />EIS predicts flow reductions ranging from 0% to 51% (resulting in an average <br />reduction of 10%, including some years in which flows would increase).' See Table <br />3.16-3, rd. at 3.16-21. This is a significant reduction - under 90th percentile flow <br />conditions, these reductions in some years would exceed 500,000 af. Id These <br />reductions are particularly significant when one considers that the "baseline" <br />conditions in the EIS assume continued Upper Basin, Lower Basin. and tribal water <br />development (and corresponding exhaustion of surplus flows). If such development <br />were to proceed more slowly than anticipated or if water use was held at existing <br />levels, the effect of this reduction would be felt far into the future. The EIS provides <br />no modeled data for flows below the 75th percentile, see FINAL EIS, supra note 71; <br />given that 75% of all flows will be less than this amount. it would be useful to have <br />reference to these data. However, one can make an educated guess: if the new criteria <br />allow the capture of an average of 30% of a 75'" percentile flow, the new criteria will <br />all but eliminate flows below Morelos Dam in normal years. <br />295. FINAL EIS, supra note 69, at 3.16-12. The accuracy of this conclusion is <br />confirmed by a comparison of the anticipated flows south of Morelos Dam under any <br />of the altematives. Under the revised 75th percentile comparisons in the EIS, for <br />example, the Califomia alternative (which allowed the deepest drawdowns) would <br />have cut flows to zero in 2002. By contrast, under baseline conditions, which would <br />not have allowed these drawdowns, significant flows would have continued through <br />2008. rd. at 3.16-20. Water has also reached the Delta when the Gila River has <br />flooded. <br />