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TABLE 21 Sediment Balance of Reduced and Redistributed Peak Flows ---------- Percent ------------- Mean Annual --------------------- Annual Sediment Load --------------- . Million Tons --------------- Years Balance Remaining Flow, cfs Deerlodge Park Mathers Hole Set to Zero --------- ---------- 90% ------------- 2140 --------------------- 2.471 --------------- 2.595 ------- 28 809 2138 2.363 2.408 14 75% .2136 2.317 2.327 3 74% 2136 2.308 2.312 3 73% 2136 2.299 2.297 0 As the daily flow pattern changes such that the peaks are reduced and the baseflow increases, the days in which the balance is set to zero declines. As expected, the total transport at Mathers Hole is greater than at Deerlodge Park, but as the flow distribution changes and the balance is not set to zero as often, the loads at both locations approach being approximately equal. Sediment Balances of Reduced. Deoleted and Redistributed Peaks When the peak flow months of April through June were reduced by various percentages, depleted, and then redistributed to power generation months of July-September and December-March, similar patterns were again observed. Tables 22 through 26 show the running balances for retaining 90%, 80%, 75%, 720, and 71% of the daily flow values, respectively, with a target depletion of 100,000 acre-feet annually. The depletion is only a target and not constant since the program currently does not allow the yearly depletion to exceed that volume gained from reducing -the peaks in each year. This function may be modified at a later time. The 100,000 acre-feet depletion target was selected because it is in the realm of earlier recommended depletions (O'Brien, 1987), and the Nature Conservancy's study (W.W. Wheeler & Assoc., Inc., 1987) discusses new consumption of perhaps 100,000 acre-feet/year under several subordination agreements. Mean annual discharges change in volume and in monthly d-istribution in this scenario. Table 27 summarizes the budgets shown in T4bles,22 through 26.