Laserfiche WebLink
<br />monthly flow data). This analysis was documented in the draft EIS on page 182, and Appendix <br />D, pages 4-5. The analyses relating to the probability of net gain in riverbed sand for each <br />alternative is documented in the draft EIS on pages 54-55, 184, 187, and 194. <br /> <br />Specific peer reviewed studies relating to the above analyses are listed in Attachment 1. <br /> <br />COMMENT: Do not change the upramp rate and maximum flow criteria at the same <br />time. While acknowledging Reclamation's good efforts to identifY and establish optimum <br />operating criteria for all users of Glen Canyon Dam, changing two flow criteria (upramp rate and <br />maximum flow criterion of preferred alternative) does not make prudent scientific sense. It will <br />not result in reliable data. Not enough information is at hand to predict the outcome of these <br />proposals. <br /> <br />RESPONSE: Viewed from the purely scientific viewpoint, it would be preferable to change <br />variables one at a time in a controlled experiment. However, many uncontrolled variables already <br />exist, and from a resource management standpoint the interest lies in measuring the possible <br />resource impact, if any, which might result from jointly changing both criteria. The best available <br />information suggests that the long-term impact of changing both criteria at once will be difficult, if <br />not impossible to detect. <br /> <br />. Even though both parameters would change, for 8 months of an 8.23 million acre foot year <br />(minimum release year), only the upramp rate will be used. The ability to operationally exceed <br />20,000 cubic feet per second only exists in months in which releases are in excess of 900,000 acre <br />feet. In a minimum release year, flows above 20,000 cubic feet per second will most likely occur <br />in December, January, July, and August. Evaluation of the upramp rates can be initiated <br />immediately with the evaluation of the increase in maximum flow relegated to the months with the <br />highest volumes. New upramp and maximum flow criteria would be recommended through the <br />Adaptive Management Program should monitoring results indicate that either of these criteria are <br />resulting in adverse impacts to the natural, cultural, or recreational (human safety) resources of <br />the Grand Canyon differing from those shown in the final EIS. <br /> <br />COMMENT: "Habitat/Beach Building Floods" designed to redeposit sediment and <br />reshape the river's topography much like the Canyon's historic floods should be conducted. <br />An experimental release based on this premise is critical to restore some of the river's historic <br />dynamics; without it, any flow regime will result in continued loss of beach and backwater habitat. <br />This "spike" should be assessed and implemented for the spring of 1996, subject to a critical <br />evaluation of its flow size, timing. impact on fisheries, and completion of a comprehensive <br />monitoring plan. Recent side-canyon floods underscore the need for restoring natural processes. <br /> <br />RESPONSE: Reclamation and the Cooperating Agencies continue to support this concept. The <br />preferred alternative supports such a flow regime. A test flow was conducted this spring. The <br />results of this flow are currently being analyzed. We expect to conduct more of these flows in the <br />future. <br /> <br />COMMENT: Endone the Fish & Wildlife Service's Biological Opinion and implement <br />