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i -. . . . ~. 27 The habitat-versus-flow curves (Figure 2) from Flow Methodology were used to evaluate the loss or gain of habitat between the environmental baseline and the environmental baseline with Ruedi and Green Mountain water sales. The analysis focused on adult habitat in September through April, and Colorado squawfish egg deposition (spawning) in July and August. Adult habitat conditions were not evaluated for May and June using Flow Methodology. During these months, Colorado squawfish are generally found in flouded backwaters or gravel pit ponds that are connected to the rivero-these habitat types are not represented in the current Flow Methodology model of the IS-mile reach. The habitat analysis is only applicable to the IS-mile reach; i.e., it does not take into account the habitat requirements of endangered fish below the confluence of the Gunnison River. Table II presents the results of the Flow Methodology habitat analysis for average, wet, and dry water years. Table 11 indicates that most of the impacts occur during the fall and winter with adult habitat being reduced an average of 1 to 2 percent per month from October through April. Impacts are most severe during dry years. Ongoing studies of the winter habitat studies of the IS-mile reach indicate that Colorado squawfish prefer deep (5-6 feet) slow moving runs--a habitat that is in limited supply in the IS-mile reach (Kaeding, personal communication). While the biological significance of these losses in habitat are not fully understood (i.e., the minimum flow necessary to maintain an adequate amount of adult habitat has not been established) the reductions in flows are occurring at a point on the habitat-versus-flow curve (Figure 2) where small changes in flow result in relatively large losses in habitat. In addition, future losses of habitat in the winter are likely, as a result of certain private actions that seem reasonably certain to occur; i.e., the agreement between Denver and the Public Service Company which would affect the way the Shoshone Powerplant's water right is administered. While no quantitative information is available at this time, this agreement is expected to further reduce winter flow and habitat conditions in and downstream of the IS-mile reach. Table II indicates that there will be some losses and gains in spawning habitat for Colorado squawfish during July and August. Spawning and recruitment appear to be the life stages most limiting the survival and recovery of Colorado squawfish in the Colorado River. As such, the Service is especially concerned about any further degradation of spawning habitat in the IS-mile reach. Specific concerns include the degradation of spawning habitat, the potential dewatering of areas where eggs have been deposited, and a reduction in flows needed to transport larvae to downstream nursery areas. It is important to note that this reach h~s already experienced a major loss of habitat during the spawning period as a result of upstream depletions and diversions. Any further loss of habitat during this period will exacerbate a situation that is already critical. The amount of water which would offset the negative impacts of the water sales is 31.7 kaf in dry years, 26.0 kaf in average years, and 25.6 kaf in wet years (Table II). These statistics reflect depletions associated with the proposed water sales (Table 9) that occur when flows in the IS-mile reach are below the 2,000 cfs optimum habitat flow for spawning and adult Colorado squawfish. By