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00u525 Interim Water Users' Agreements to make 10,825 AF available for the 15 Mile Reach. These contracts make water available from a variety of sources including Green Mountain, Wolford Mountain, and Williams Fork Reservoirs. No Action Alternative Sport Fisheries. Releases from Ruedi for operations and contract obligations primarily occur outside of spawning and critical early development life stages for brown and rainbow trout in the Fryingpan River as shown in Table 3.4. The fIrst two weeks of spawning and egg incubation would occur before releases are expected to drop to the winter release level of the lesser of 39 cfs or inflows. Releases would be gradually reduced so that fIsh would be able to migrate to the larger, year-round pools. Winter flows of the lesser of 39 cfs or inflows are believed to have potential to impact brown trout incubation by limiting access to redds, limiting movement for incubation, and exposing eggs to de-watering and freezing. Smith and Hill (2000) believe that flow changes greater than 25% can have a negative impact on trout fIsheries. No dramatic changes in flows (that is, changes in flow greater than 25%) are anticipated during releases from August 1, 2002 to November 1, 2002. In general, changes in flow would reflect past release practices which have been kept well below 25% of current flow. Changes in flow greater than 25% are generally "ramped" over multiple days to minimize impacts. In addition, a 2001 CDOW (Colorado Division of Wildlife) study investigating whirling disease indicated that fluctuations in stream flows are not a signifIcant causal agent of species losses. The study states, Suggestions that fluctuations in habitat quantity and quality signifIcantly contribute to the unusual mortality observed in year classes of wild rainbow trout are not supported by our fIndings. The loss of rainbow trout year classes has occurred in major reaches of the Cache la Poudre, Colorado, Dolores, Fryingpan, Gunnison, Rio Grande, South Fork of the Rio Grande, South Platte, and Williams Fork Rivers in below average, average, and signifIcantly above average water years with no corresponding impact occurring among brown trout year classes. This invalidates the argument that drought, floods, and the concomitant fluctuations in stream discharge are implicated in the lo~s of rainbow trout year classes. Similarly, a stressful thermal regime cannot be implicated in the unusual loss of rainbow trout recruitment (pp.73-74). Macroinvertebrates represent a signifIcant food source for trout species; their presence is important to maintaining a productive fIshery. Of the basic physical requirements necessary to sustain macroinvertebrate populations, river depth and flow velocity are the most critical (Nelson and Roline, 1996). Significant fluctuations in flow velocity and depth can have negative effects. Flow fluctuations seen below Ruedi Dam under No Action are expected to be less than 50 cfs per day, which would not have a negative effect on macroinvertebrates. This variation is typical for a high mountain environment like the Fryingpan, where summer storm events are common, and these species are adapted to fluctuations of this nature (Roline, 2001). Maintaining winter flows at a level suffIcient to sustain macroinvertebrate populations is also important: if the river is allowed to freeze over entirely or in large part, fewer individuals may survive the season. The winter (November 1-Apri130) minimum instream flow established for the Fryingpan between Ruedi and the Roaring Fork is 39 cfs established by the CWCB subsequent to amendment of the Fryingpan-Arkansas Operating Principles to protect the stream biology of the Fryingpan. The Operating Principles, as amended, stipulate that Ruedi Reservoir winter releases are to be the lesser of 39 cfs or inflows to the reservoir. Under No Action, winter release rates are anticipated to be at 39 cfs or inflows, whichever is less, in accordance with the principles. Reclamation typically operates Ruedi to release 39 cfs, or more, from November 1 through April 30 15