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4-12 Chapter 4 - Reallocations Example. (1). Lost Flood Control Benefits. Limited information was available to determine the benefits foregone if water storage is reallocated from flood control to water supply. Primarily, available data from the Sac River basin were used for this study. Stage-damage data from the original project justification and a 1974 reevaluation report were analyzed for the Sac River. The decrease in flood damage reduction benefits that would occur along the Sac River as a result of a reallocation from flood control storage were expressed as a proportion of overall damages. This proportional reduction was then applied to the current estimated flood control benefits for Stockton Lake, which were updated for this analysis. Available data for the downstream rivers (Osage, Missouri, and Mississippi) were insufficient for producing a reliable estimate of impacts. Therefore, a range of benefits was developed. The upper limit assumed that the downstream rivers would receive the same proportional impact as the Sac River; i.e., that a pool raise causing a one percent reduction in flood control benefits on the Sac also would cause a one percent reduction on the other three rivers. The lower limit assumed that there would be no impact on Mississippi flood waters, but that the impact on the Osage and Missouri Rivers would remain the same. All annual benefits were adjusted to current price levels and the lower limit was established as 0.4 percent of the total annual benefits ($217,700) and the upper limit was established as 1.3 percent of total annual benefits ($665,200). (2) . Lost Hvdropower Benefits. A two foot raise ln the multipurpose pool would not entirely offset all hydropower benefit losses at Stockton and would not reduce the hydropower losses at the downstream hydropower projects (Harry S. Truman and Bagnell) . These values were computed by the North Pacific Division based on information provided by Southwestern Power Administration. The computations are similar to those shown in Table 4-3, with the same capacity and energy values. The total hydropower benefit foregone from reallocation of 50,000 acre-feet of flood control storage was computed to be $2,309,811. (3) . Lost Recreation Benefits. No loss of recreation benefits would be anticipated as a result of an increase in the multipurpose pool even though impacts to recreation facilities and fish and wildlife habitat were identified and are explained in detail in the Environmental Effects paragraph. Most of the impacts would be eliminated by modifying recreation facilities and increased maintenance. These mitigation measures would be paid for by the water supply customer if storage is reallocated from the flood control pool. .. ~:.../