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Flood Control The Water Control ManuaP for Blue Mesa Reservoir indicates that releases should notcause the flows of the Gunnison River at Delta to exceed 15,000 cfs unless necessary. The City of Delta has indicated that they begin to experience flooding at flows of approximately 12,000 cfs. The following table shows the number of days various flows were exceeded at Delta during the 26 year study period. Number of Davs Flows at Delta were Exceeded Run A RunB Rune RunD Flows at Delta Baseline FWS 5000 FWS 6500 FWS UNL TD 12,000 cfs 71 81 84 84 13,000 36 48 49 49 14,000 15 27 29 29 15,000 9 13 13 13 17,000 2 5 5 5 19,000 0 2 2 2 The table above shows increasing releases during May, in an attempt to meet the peak flow recommendations, increases the frequency of flows above 12,000 and 15,000 cfs at Delta. Reclamation would be taking risks when creating spring peaks. If the inflow forecast were overestimated and the recommended spring releases were made, Blue Mesa might not fill. If the inflow forecast were underestimated and water for a spring peak were retained in Blue Mesa, it might become necessary to release water that causes flooding at Delta. This is a concern because Reclamation may not be able to respond to rapid changes in hydrologic conditions. Reclamation would monitor such operations and make adjustments as necessary to balance competing needs. These model results are not intended to predict exact or specific flooding impacts on Delta, but provide a general indication of flooding impact potential. General observations from model runs indicate that flooding at Delta may be increased under the conditions summarized in the following table: Potential for Flooding at Delta, Colorado Wet (Upper 10% category) Moderately Wet to Wet (Upper 10% - 30% category) equal toOT greater than forecast increased equal to or greater than forecast increased 3Reclamation and the U.S. ArmyCorps of Engineers document dated February 1988. 13