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II The flows remaining at the top of the 15-mile reach (after accounting for the net reductions due to Ute diversions) were compared to monthly flow recommendations made by the USFWS in their May 1995 report. From this comparison, a potential make-up flow requirement was computed. The annual historic flows at the top of the reach for the 1975-1993 modeling study period were divided into the four flow groupings recommended by the USFWS to determine the USFWS monthly targets for each year. Each group is identified by a percentage which signifies the percentage of years during which the average annual flow exceeds a specified value. The historic flow record was divided into the four groups by ranking the annual flows and computing the 25th, 50th, 80th, and 100th percentiles, and then assigning each of the 19 years to the applicable group. When the reduced 15-mile reach flows were less than the target flows, amake-up requirement was calculated as the lesser of Ute Water's net impact to flows or the amount of water needed to bring the flow up to the target. When the reduced flows at the top of the 15-mile reach exceeded the USFWS targets, it was assumed that no make-up flows would be required. This approach was agreed to by the USFWS during informal consultation. The USFWS has indicated that the calculated make-up flows would be used to measure the impact of tTte Project on the 15-mile reach. Under Phase I of the Project (as discussed in the Biological Assessment), the RIPRAP is assumed to be providing suff cient progress toward recovery of the fish - sufficient to cover the make-up flows up to 1500 ac-ft/yr. Under Phase II, the RIPRAP would cover make-up flows up to 3000 ac-ft/yr after the USFWS raises the threshold to this value. Make-up requirements exceeding 3000 ac-ft/yr would be covered under Phase III. Table 3.11 and Figure 3.16 summarize the results of the revised hydrology. The baseline year for the projections is the same as that used for estimating depletions to the Colorado River Basin, as described previously, with a baseline demand of 6,945 ac-ft. Demands are projected to grow to 13,311 ac-ft/yr over the next 20 years, and reach 28,589 ac-ft/yr by the year 2045. Over this same time frame, it is projected that reductions in 15-mile reach flows due to Ute Water's future diversions wily grow to 5,005 ac-ft/yr and 18,603 ac-ft/yr by 2015 and 2045, respectively. Note .that while annual demands will increase by 21,644 ac-ft through 2045, flow reductions will only increase by 18,603 during this same period. The increase in flow reductions is less than the increase in demands for two reasons: ^ Part of the District's future demand will be met using water rights which have historically been diverted for agricultural use. When these rights are transferred to municipal use, diversions are limited to the historical volumes consumptively used. Therefore, no increase in depletions will occur due to the District's diversions. ^ During periods when a call is on the Colorado River due to demands by the Grand Valley Project and Grand Valley Canal (the Cameo call), many of the District's direct flow water rights are protected by replacement reservoir releases to replace any out-of-priority diversions by these rights. These releases are accounted for in the hydrologic assessment based on the manner in which the releases are administered by the Colorado Division 5 Engineer. r CDM Camp Dresser & McKee 0:8047-I10~DOCWPPEND-B.DOC B-17