WSP06185 - Laserfiche WebLink

Home Browse Search

, added to the Preferred Alternative and we have considerable concern about their ramifications. 1;. " " ELEMENTS OF THE PREFERRED ALTERNATIVE operating levels of the dam under Interim Flows would be continued if the Preferred Al ternati ve is adopted. However, scientific information now suggests modifications to various parts of the Preferred Alternative could be made with probable further environmental improvements, little risk to downstream resources and significant benefits to hydropower. * Small upramping rates as required under Interim Flows were found to be unnecessary to prevent sandbar erosion. Scientists found no evidence that raising the maximum upramp of 2,500 cfs/hour under Interim Flows to 4,000 cfs/hour would be detrimental to downstream natural or cultural resources. * Scientists also found no evidence that infrequent raising of ,the maximum release from 20,000 cfs to 25,000 cfs would be detrimental to downstream natural or cultural resources. '. !':* /; ./; * Riparian plants at the upper elevations of the New High Water Zone would receive periodic watering and thereby enhance their survival chances. t.''' ;..~ * High elevation wet and dry marshes would begin to grow in size and number as less would be subject to drying or drowning as occurs under more steady flows. ',. :,,: .... * Reductions in sloughing of Cladophora would be reversed somewhat thereby enhancing food supplies for Humpback chub and other aquatic species in the lower river. Modifications to the maximum release criterion and the maximum upramping were debated by the Cooperating Agencies and other interested parties in a consultation process mandated by the 1992 Grand Canyon Protection Act and unanimously accepted. These changes should be incorporated into the final Preferred Al ternati ve adopted in the Record of Decision. In addition to the need to modify the Preferred Alternative, we have some concerns regarding the analysis of economic impacts. -4 ~ :'; LJ :~~. ., , r,~ .-:. .', ":'"t 7 ~~ ", ~~ * The negative direct impacts to the hydropower sector dwarf any direct positive impacts resulting from changing flows. The present value of positive impacts for recreation is $43 million and negative impacts for hydropower is $888 million. * Presently, recreation benefits are based on opinions as to what would be paid (willingness-to-pay) but power impacts are 7