WSP09978 - Laserfiche WebLink

Home Browse Search

combined with the filling (or almost filling) of altupstream reservoirs and a 2,297 MCM (1.862 MAF) gain in storage in Lake Mead, is enough to eliminate most of the storage deficit that has accumulated over the 6 previous drought years, It is expected that over 8,680 MCM (7,036 MAF) of storage will be gained in water year 1993, It is now estimated that 2 normal flow years would completely fill the system, During 1993, all deliveries of water to meet obligations pursuant to "The Law of the River" were maintained. Tables 1(a) and 1(b) list the expected October 1, 1993, reservoir vacant space, live storage,' water elevation, percent of capacity, change in storage, and change in elevation during water year '1993. 1994 WATER SUPPLY ASSUMPTIONS For 1994 operations, three reservoir unregulated'inflow scenarios were developed and analyzed and are labeled as probable maximum, most probable, and probable minimum. The attached graphs show these inflow scenarios, and associated release patterns, end of month contents, and end of month elevations for each reservoir, The National Weather Service Extended Streamnow Prediction (ESP) computer model uses current basin conditions as well as historical data to predict the range of possible future streamflows, The ESP model was employed to develop each inflow scenario, based on current soil moisture conditions within:the basin. Although there is a wide confidence band associated with streamflow forecasts made a year in advance, the data are valuable in analyzing the possible impacts on project uses and purposes. Due to the above average year that was experienced in 1993, the soil moisture deficit has been erased and therefore the magnitude of inflows in the three scenarios are equal to the historical upper decile, mean, and lower decile (1.0 percent exceedance, SO percent exceedance, and 90 percent exceedance, respectively) for each reservoir, Based on the ESP model results, three different hydrologic scenarios were developed for each reservoir. The three inflow scenarios for Lake Powell are shown in Tables 2(a) and 2(b), The volume of inflow resulting from these assumptions was used as input into Reclamation's monthly reservoir simulation model. This model is used to plan reservoir operations for the upcoming l2-month period, 'Projected water year 1994 inflow and. June 30, 1993, reservoir storage conditions were used as input to this model and monthly releases were adjusted until release and storage levels accomplished project purposes and priorities, 4. I .' I I I, t I I I .- I t I -, I I , ., I