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<br />Basin is greater than 602(a) Storage. Article 11(1) of the Operating Criteria describes <br />602(a) Storage. <br /> <br />There is no provision in the Operating Criteria to equalize the level of Lake Powell with <br />Lake Mead during times of drought when reservoir storage in Lake Powell is lower than <br />Lake Mead. However, river simulation modeling of the Colorado River system shows <br />that in the future there will be times when Lake Powell storage will be greater than Lake <br />Mead. This will occur because of the application of602(a) Storage provisions. See <br />Colorado River Basin Project Act at Section 602(a). Following a drought, the 602(a) <br />Storage provision in the Operating Criteria allows Lake Powell to refill to a level <br />sufficient to protect the Upper Basin from future droughts. Releases greater than the <br />objective minimum are not made from Lake Powell until this level of storage is achieved. <br />It is likely that when the current drought comes to an end, during a year (or series of <br />years) with above average inflow to Lake Powell, reservoir storage in Lake Powell will <br />exceed that of Lake Mead. <br /> <br />In 2004, anlnterim 602(a) Storage Guideline was adopted that set 14.85 million acre-feet <br />of storage (elevation 3,630 feet) at Lake Powell as the minimum level for 602(a) Storage <br />through the year 2016. See 69 Fed. Reg. 28945 (May 19, 2004). Under this interim <br />guideline, releases greater than the minimum objective release will not be made when <br />Lake Powell is projected to be below elevation 3,630 feet. Thus, while Lake Powell <br />storage decreases faster than Lake Mead during periods of drought, the 602(a) Storage <br />provision allows Lake Powell storage to rebound quicker than Lake Mead when there is a <br />return to average or wetter than average hydrology. In addition, see response to <br />Comment No. 34. <br /> <br />Comment No. 39 - (Letter No. 19): Presently, there exists a large imbalance between the <br />water volumes in Lake Mead and Lake Powell (14.3 million acre-feet to 8.8 million acre- <br />feet), which has jeopardized the interests of the Upper Basin and put at risk the future <br />generation of hydroelectric power at Glen Canyon Dam. . <br /> <br />Response: The severity of the drought over the past five years in combination with the <br />objective to maintain a minimum release of8.23 million acre-feet has caused a significant <br />drawdown of Lake Powell. The minimum release objective contained in the Operating <br />Criteria results in Lake Powell storage decreasing during periods of drought. From 1988 <br />through 1992, there was a five-year drought in the Colorado River Basin and the water <br />surface elevation of Lake Powell decreased by 89 feet. The drought of ~he past five years <br />(2000-2004) is more severe than the drought that occurred from 1988 to 1992. Records <br />show the cUI:rent drought to be the most severe five-year drought in the Colorado River <br />Basin in over 100 years of record keeping. Because of this, Lake Powell has experienced <br />a significant reduction in storage. <br /> <br />Elevation 3,490 feet at Lake Powell has been identified as the minimum level at which <br />hydropower can be generated at Lake Powell. The river bypass tubes at Glen Canyon <br />Dam can release water as low as elevation 3,370 feet, but no hydropower can be <br /> <br />24 <br /> <br />