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001266 ~ Draft Task 7 Technical Memorandum . Results of these tests indicate some small changes to demand shortages and reservoir contents with changes to the contemplated draft. The model run using a higher contemplated draft results in Elkhead Reservoir operating an average of 1,670 af lower each month. Future demands were shorted an average of 245 af per year more than under the Wheeler contemplated draft model run, or approximately 6 percent. When the contemplated draft was reduced by 5 %, modeled Elkhead Reservoir contents were an average of 1,590 af higher. Modeled shortages to future demands were reduced by an average of 358 af per year, or approximately 8 percent. The effects of a modified contemplated draft on Elkhead Reservoir contents were _ considered negligible for this study. Following these sensitivity tests and the approval of the Colorado River Water Conservation District, the instream flow requirement at Juniper was defined for modeling purposes as the original W.W. Wheeler contemplated draft of the Juniper Project. Results of Scenario Demand Shortages Modeled shortages to existing senior demands in Scenario II were identical to those predicted in Scenario I (Table 4). This was as expected because the instream flow right was modeled as junior to existing demands and should have no effect on them. Existing demands junior to the 1954 Juniper rights were significantly impacted by defining the contemplated draft as an instream flow requirement. Shortages to existing modeled juniors averaged 4,044 af/yr over the study period. In model runs which operate at future demand levels, the Juniper right, as converted to an instream flow, frequently calls out the future demand increments. All future level demand increments were located above Juniper Canyon in the model. Shortages to the future demand increments average 454 af/yr and 11,030 af/yr for the 2015-level and 2040-level conditions, respectively (Figure 7). Reservoir Contents When the Juniper instream flow right calls out junior demands, a significant draft is placed on existing storage accounts. Elkhead Reservoir was drawn down to its minimum pool in most years during the late summer and fall months (Figure 8). This leaves numerous shortages to certain Craig area demands whic):l have no access to storage in Stagecoach. Releases from Stagecoach Reservoir were frequently limited by the capacity of the reservoir outlet thereby preventing shortages from being met from that water source. SCENARIO III. ENLARGEMENT OF ELKHEAD RESERVOIR. Key Assumptions of Scenario Scenario III is similar to Scenario II in that it includes the instream flow right at Juniper Canyon but also includes the simulation of an enlarged Elkhead Reservoir. The enlarged Elkhead Reservoir was modeled with a total capacity of 52,000 af. A capacity of 52,000 af would require raising the water surface approximately 30 feet: The size of the enlargement pool is 38,300 af. The enlargement pool was modeled to fill ahead of the Juniper instream 11 ,..11- .-'i..