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For the low-water, post-Aspinall years, flows peaked during the first 10- day period in June. Flows abruptly decreased to the lowest level during the first 10-day period in July. Flows remained below 300 cfs from July to the second 10-day period in September. Flows during September and October usually increase in the 2.3-mile reach when irrigation demands decrease. The mean daily flow for each 10-day increment is provided in Figure 8 and Appendix; Table I.1. The low-flow years, 1917-1938, were climatologically wetter than either the 1939-1966 or 1967-1995 period. The lowest water years were 1931 and 1934 (Appendix; Table I.2.). Using the mean daily flow by 10-day time steps, a bi- modal peak occurred during the second 10-day period in May and the second 10-day period in June. The flow then abruptly declined to 0 cfs the first 10-day period in August. This descent of the hydrograph was similar for both pre-water development and post-Aspinall periods. However, from peak discharge to base discharge, flow duration was longer during the pre-development than post-Aspinall period (Appendix; Figure I.1.). The low-flow period in July and August is a critical period biologically for Colorado squawfish. A minimum flow of 300 cfs in the 2.3-mile reach is necessary to maintain access for fish moving up- and downstream from the fish passageway. The presence of sub-adult and adult Colorado squawfish in the reach suggests that this has importance in addition to a passage corridor. The high use by squawfish during this period suggest that this reach might be a spawning or post-spawning feeding area. Therefore, to maintain 300 cfs for fish in the 2.3-mile reach, 70-75 days of augmenting the flow with releases from upstream Federal reservoirs is required during a low-water year. For moderate-water years, flows peaked during the second 10-day period in May. The flow gradually decreased until the first 10-day period in August when mean daily flow was about 875 cfs. The lowest flow calculated was 860 cfs during the first 10-day period in September. Although the lowest mean daily flow calculated for a 10-day period was about 861 cfs during the first 10-day increment in September, there were days during moderate years when flows were less than 300 cfs in the 2.3-mile reach. In 1969, there were 9 days in July and August when flows were less than 300 cfs. Likewise, in 1975, there were 22 days i n Jul y and August when fl ows were 1 ess than 300 cfs and 9 days i n September when flows were 0 cfs (Figure 9). For these reasons, it is important for water managers to be aware that even during moderate-water years, there can be instances when flows less than the recommended minimum flow might occur. Furthermore, it is disadvantageous to average flows for several days over several water years because there are occurrences that go undetected when flows may fall below the recommended minimum or a stream reach could be dewatered. Minimum Flow Recommendation The assumptions for establishing a minimum flow in the 2.3-mile reach of the Lower Gunnison River were discussed earlier. The most critical assumption was that Colorado squawfish need at least a water depth of 1 foot to move both up- and downstream within the reach that have critically shallow water depths. Three areas within the reach, transect 9, 19, and 20, were identified having maximum water depths at or slightly less than 1 foot at flows ranging from 245- 31