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039 MODELING RESULTS Results of the Recursive Simulation Model applications to the Eno River Reservoir System focused primarily on the effects on storage in Lake Orange. Lake Orange Drawdown--Under the rules of Model #1, full withdrawals by Orange-Alamance and Hillsborough while maintaining full pool in Corporation Lake and Lake Ben Johnson, Lake Orange is drawn down a maximum of 12.75 feet. This corresponds to a reduction in storage of 1192.5 acre-feet (out of 1402.5 acre-feet total) leaving approximately 14 percent of the original useful star- , age volume'in the reservoir. Under the rules of Model #2 (set cutbacks in withdrawal rates by Orange-Alamance and Hillsborough and set cutbacks in the Lake Orange minimum release while maintaining full pool in Corporation Lake and Lake Ben Johnson), Lake Orange is drawn down a maximum of 10.36 feet. This correponds to a reduction in storage of 1064.5 acre-feet (out of 102.5 1 acre-feet total) and leaves approximately 24 percent of the original useful storage volume in the reservoir. Under Model /1, Orange-Alamance and Hillsborough are able to maintain full withdrawals at all times during the 50 years of record. These with- drawal rates are 0.38 MGD and 2.75 MGD, respectively. The minimum release 1 for Lake Orange of 1.3 cfs is also met at all times. Under Model #2, operating rules for conservation during drought periods can be seen In Table 2. The resulting withdrawals by Orange-Alamance and Hillsborough and minimum releases from Lake Orange are seen in Tables 3 and 4, respectivelY. All withdrawals and the Lake Orange minimum release are met during the entire modeling period of record. Model #2 also illustrates the effectiveness of conservation measures in reducing the impact of drought on water supply impoundments. Figures 14 through 117 show the impact of the drought of 1933-1934 on lake levels of Lake Orange under Models #1 and #2. Supporting information can be found in the attached graphical illustration's (figures 1 through 17). These figures include: 1) stage- storage curves for each reservoir, 2) outflow-duration curves for each reservoir under both models, 3) drawdown and storage remaining curves for Lake Orange, and 4) Lake Orange lake levels during the 1933-1934 drought under bath models. 1Erosion andiSediment Inventory for North Carolina, U.S. Department of Agriculture Soil Conservation Service, table 2. 2Brune,G.M. "Trap Efficiency of Reservoirs", Trans. Am. Geophysics Union, Vo1.34 (June 1953), pgs.407-418. 3Boriand,W.M.1, and Miller,C.R.,"Distribution of Sediment in Large Reservoirso;Journal of the Hydr. Division.ASCE,Vol.84,No.HY2,April 1958.