Feasibility Report and Environmental Impact Statement
Average Water Yield
Under the reallocation alternatives (#3 and 4), 15 regional water users that hold existing surface rights on the South Platte River or Plum Creek would share the new storage space in the joint flood control-conservation storage pool, storing stream flows that could cause fluctuations in lake levels in Chatfield Reservoir. The actual yield of water supplies that would be realized from use of new storage space through a reallocation would vary every year, and would not necessarily equal the 20,600 or 7,700 acre-feet of storage capacity alternatives reviewed under the EIS.Several factors, including precipitation, runoff and the seniority of water rights, play key roles in the availability of water and storage opportunities in any given year.The water rights of the 15 users are generally junior in their relative priority, and therefore are expected to be available for diversion less frequently, yielding less or no water in low-flow years. Under Alternative 3 in the average year, water users estimate the average yield to be approximately 8,500 acre-feet per year.
Under Alternative 4 in an average year, the average yield is estimated to be approximately 3,700 acre-feet per year.