C153773 Feasibility Study - Laserfiche WebLink

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I I I I I I I I I I I I I I I I I I - The most critical water use month, with the lowest end-of-month reservoir storage, would have occurred in July of 1955 under the assumptions made. Starting with only the Morrison Operating Reservoir full in January 1950 as a start date for modelling parameters, and with water demands of 1,290 EQR, Cooley Reservoir would not be able to fill completely until July of 1952, two and a half years after initial filling begun. This assumes no "free water available" and that water could only be diverted under priority. Once the Cooley Reservoir is full in 1952, the following series of three drought years, beginning in 1954, uses almost all water storage by July 1955. Thereafter, the reservoir begins filling again and almost regains full capacity in August of 1957. The amount of water that could be pumped into the Cooley Reservoir every month is based upon the total water available for storage with the existing water rights and the storage in the reservoir at that month. If the reservoir is full, only make-up water for evaporation and seepage is pumped into the reservoir. If the reservoir is not full, all water available for storage will be pumped into the reservoir until it is full. The computer model for this operation study shows that in the wet years of 1952 and 1953, when the reservoirs were full, approximately 206 acre-feet of additional water could have been stored, but was not diverted. If Cooley Reservoir is enlarged to 600 acre-feet, Morrison would be able to store all water available under their present water rights during the model period of 1950 to 1957. With this additional storage, Morrison could serve up to 1,475 EQR. A copy of this model run is shown in the Appendix, Tables 2A to 2H. Figure II-C shows the storage volume throughout the 8-year study periOd for a scenario with 1,475 EQR. The maximum average monthly flow rate available for delivery to storage is determined by the model to be 1.6 cfs. Instantaneous diversions may be higher, therefore, a pumping rate of 2.5 cfs is recommended for filling Cooley Reservoir. In summary, Morrison's present water rights portfolio will allow for 4.45 cfs diversion from Bear Creek into the treatment plant, but the filling rate into the Cooley Reservoir need not be more than 2.5 cfs. B. EXISTING RAW WATER DELIVERY SYSTEM The existing raw water intake system consists of a diversion dam and intake screen on Bear Creek, at approximate elevation 5990 feet. A concrete weir check dam structure in the creek maintains a water level to the intake screen. In 1983, flooding on Bear Creek washed out the check dam and a new concrete weir was constructed as an emergency replacement. The system is presently constructed to route floods over the weir, and around the intake area to the 70-0SO.03S:MSTR.PLN II-7