Laserfiche WebLink
<br /> <br />19 <br /> <br />Following the extreme flood runoff years of 1983 through 1986, the Glen Canyon <br /> <br />Environmental Studies and reports identified releases greater than powerplant <br /> <br />capacity as detrimental to the ecology of the Grand Canyon and recommended that <br /> <br />steps be taken to limit the frequency of these flood releases. Based on these <br /> <br />recommendations and similar concerns regarding powerplant bypass voiced by the <br /> <br />power customers, an operating strategy was developed within the constraints of the <br /> <br />existing Operating Criteria for Glen Canyon Dam that reduced the probability of <br /> <br />releases greater than powerplant capacity. The frequency of these releases was <br /> <br />reduced from approximately once in four years to approximately once in 20 years. <br /> <br />In addition to reducing environmental damage, this also has the effect of decreasing <br /> <br />spillway maintenance and repair costs and increasing total power generation, <br /> <br />This operating strategy is based on (1) a reduction in the July target storage content <br /> <br />of Lake Powell by 500,000 AF, and (2) a more immediate response to updated <br /> <br />forecasts as the runoff season progresses. These factors contribute to an operating <br /> <br />flexibility during the late spring which can accommodate large increases in the <br /> <br />forecasted spring runoff such as occurred in 1983, 1985, and 1986. <br /> <br />Because the level of Lake Powell has dropped considerably since 1987, the risk of <br /> <br /> <br />releases greater than powerplant capacity during water year 1992 is negligible, <br /> <br />Test interim minimum and maximum releases and controlled fluctuations have been <br />