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001107 . . to 590 cfs during peak runoff periods. Modeled flows during August and September are often less than 5 cfs. Average annual outflow from the reservoir is approximately 63,000 af, due to annual evaporative losses of roughly 1,400 af. As a note, reported zero flow conditions are, to some degree, an artifact of modeling assumptions. Typically, a minimum of 1 to 2 cfs are present in Elkhead Creek downstream of the reservoir resulting from reservoir seepage and return flow. The seepage component of flow below the reservoir was not represented in the model. Yampa River - Maybell Table 4 shows modeled monthly flows of the Yampa River at Maybell under baseline conditions. Figures 6A through 6L present monthly flow exceedance curves based on these modeled flows. Average monthly flows range from a low of 139 cfs in September to a high of . 5,626 cfs during the May runoff period. Occasionally, there are zero flow conditions predicted . by the model at Maybell during the late summer and early fan. However, a minimum of 25 cfs is typically present downstream of the Maybell Canal as a result of leakage around the ditch headgate and return flows to the river. Leakage and return flows from the Maybel1 canal above the Maybell gage were not represented in the model. Table 5 presents the modeled 25th, 50th and 75th percentile flows at Mayben for the baseline condition. Table 5 Modeled Baseline Flows at Maybell (cfs) Month October November December January February March April May June July August September Post-Project Conditions 25% exc. 50% exc. 75% exc. 312 341 314 277 330 713 3,096 7,005 6,363 1,753 368 191 229 251 221 211 251 492 2,068 5,754 5,147 999 220 119 154 207 174 175 231 383 1,368 4,033 3,644 444 91 58 I, The post-project scenario, I.e. with the Elkhead Reservoir enlargement, was defined in the Hydrosphere model by a projected demand level representing year 2040 conditions and by operation of Elkhead Reservoir enlarged to a capacity of 44,900 af and a primary outlet capacity increased to 655 cfs. The 2040 demand condition includes an additional consumptive demand of approximately 38,000 af over conditions in the baseline scenario. Included in the 38,000 af demand increment is approximately 14,000 af of demand associated with future growth in municipal and agricultural water use. The remaining 24,000 af of demand is associated with construction of new thermal electric generation capacity at the Hayden and Craig stations, a new coal-gasification plant, and new mining facilities. In most instances, these future depletions would be expected to occur using existing water diversion facilities and water rights. 19 1._