WSP03375 - Laserfiche WebLink

Home Browse Search

" Conditioned most probable water supply forecasts for the coming operating year, dur ing this per iod, are subject to a large degree of uncertainty, and careful consideration must be given to the probability that some variance from this forecast will occur. The 24-month study computer model would be used to explore the sensitivity of excess water availability under various water supply scenarios. Consistent with the overriding principle of preserving conservation, consideration for shifting or redistributing excess releases anticipated to occur in the coming operating year to this period, July through September, should be given if a conditioned lower quartile water supply forecast for January-July runoff (or a conditioned minimum probable water supply forecast, if warranted) would result in excess water releases in the coming water year. The use of a conditioned lower quartile water supply to govern July through September releases, as opposed to a most probable during this period of high forecast uncertainty, unless it can be justified otherwise, would reduce the likelihood that such release decisions would result in a loss in conservation storage as the result of forecast errors. Inasmuch as a conditioned lower quartile water supply would revert river operations back to a user-defined release pattern between January and July in the coming operating year, conservation storage can be preserved so long as reservoir storage conditions at that time are no different than they would have been under the Base Case. Reservoir vacant flood control storage space would always be equal to or greater than the minimum required by Hoover Dam Flood Control Regulations but, if greater, would reflect a balance with releases so as, again, to ensure that reservoir storage conditions would be no different than they would have been under the Base Case when operations revert to a user-defined release pattern. The 24-month studies allow for these types of analyses. Consideration would also be given to excess water release adjustments to more uniformily bridge, to the extent consistent with optimizing any potential additional benefits, releases between months. 3.3.3 October through December. Excess releases dur ing this period, if deemed necessary, serve primarily to reduce the probability of making subsequent high flood control releases in excess of 19,000 cfs, and provide greater operating flexibility from next January through July. However, power plant flow capacity is generally reduced during this period of low water use/low river flow to perform scheduled power plant maintenance. The flow capacity at the Parker Dam power plant, the critical capacity, ranges between 16,500 to 17,500 cfs during this period. With respect to generation revenue, power value is much higher in December -32-