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\ -") ;. I e e 002179 Channel catfIsh (lctalunJs punctatus) Kokanee salmon (Oncorhynchus nakA) Rainbow Trout (Oncorhynchm mykis~) Other fIsh species present, but not stocked by CDOW or USF&WS include the following: YeUow perch ~ flllvescens) _ Black bullhead (lctalunlS md!W Green sunfish CLepomis cvanellus) White sucker (Catostomus commersoni) Flannelmouth sucker (CAtostomus latipinni<;) Bluehead sucker (Clltostomll~ di<;coOollls) Reservoir fluctuations are related to spring runoff, rd~es to the Dolores River, and irrigation and municipal and industrial water demands supplied by rd~es through Great Cut Dike and the Dolores TUIlDel. Losses to the reservoir fIshery are associated with the method of spill releases. . Use of the dam spillway in 1993, required by ongoing repair of the outlet works, resulted in the loss of a number of trout and Kokanee salmon from the reservoir. Managed spill releases through the lTlain outlet works have resulted in far fewer fish being lost downstream. E~'VIROl\'MENT AL CONSEQUENCES Trout Fishery Proposed Action - Aquatic studies conciuded that during summer periods a flow of 50 cfs or less does Dot provide suitable water temperatures ouring the summer months for trout throughout the 12 mile section. It was also determined that flows of 50 cfs or less d~s not provicie sufficient depth of water in several riffle areas to aliow trout to move throughou~ the system. It was estimated that 70 cfs flows would be necessary to provide suitable temperatures and adequate depth in riffle areas for migration during the summer months and somewhat lower flows would be adequate during the spring and fali due to iower temperatures. Winter flows of 30 crs during the stuciy period did not appear to rietrimentaliy affect the trout fishery. However, there is e possibility of icing problems rieveloping at low flows in severe winters but management flexibility would aUow these problems to be corrected. Prolon!;ed severe drought periods wili result in project water shortages. The 46-year project operation smciy iDciicates droughts that would produce significant shortages and adversely efiect the trout fishery would occur in about 4~ or the years. Additional hydrological records indicate that significant shortages would occur in less than 3 ~ of the yearo . and statistical analysis or the datR inaicates that the OCCUl'lUlce of significant shortages would be even less. Releases in anticipation of spills (controlled rdeHse of water which would bt! excess to available storage space in the reservoir) have occurred in all years of the interim op<::ration. Therefore. the adequacy of a 30,100 AF or 29.300 AF fish pool has never been evaluated. Overall, the data clearly indicates that pool management is a much more effective way to maintain the tail water trout fishery in the Dolores River. In a report provided to Reclamation in 1993 by the CDOW. the fishery researcher concluded that the. ...Dolores River and the aquatic biota that support the trout fIshery downstream from McPhee Dam may well be in the healthiest condition since reservoir operations began in 198~.. (Nehring 1993). Implementation of the proposed action would provide flows in the river to improve habitat for trout in the Dolores River below McPhee Dam. Sufficient water would be available to meet the summer flow requirements. Toe maIUlgement flexibility provided by the pool would allow the reserved water to be released in the best way possible to benefIt the dov.nstream fishery, Under tius alternative, both the quantity and quality of habitat would be increased from the existing conditions and from the conditions provided by the no action alternative. The biomass of trout in the river would be expected to increase. ~o Action - The t'o Action Alternative woule resuit in periodic loss of much or the trou: fishery below toe ciam during yc:ars designated as "d::.01 v.:itr. 20 cfs rcj~HscS uncier the :>PRf::-ES criteria (-approxunateiy 20 ~ or tne ILIne;.