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; , , =~~ Ilow would b~ maintained at a critically low 20 cfs throughout the year. Therefore, the proposed action would benel;t those species dependent On the aquatic environm~nt. Species closely associated with floodplain riparian and wetland communities could be affected if changes in Ilow regimes in the river significantly alter the groulldwaler level for extended periods or at crucial times. Riparian and wetland vegetation is typically dependent on groundwater for its maintenance and would, therefore. be affected by any significant alteration of the groundwater regime. However, becausc watcr relcascs 10 the Dolorcs River would change largely in timing, rather than volume, it is anticipated that little effcct will result to the water table in the adjacent floodplain. Although the proposed action would typically maintain higher flows.more frequently in the summer and lower flows more frequently in the winter, the actual magnitude of those changes seems unlikely to have much effect on the water table, even seasonally. Consequently, significant changes to the floodplain vegetation communities are not expected, and therefore, to the wildlife species dependent on those communities. ALTERNATIVES 1 and 3 - These are essentially the same from an ecological standpoint and would not differ in their biological effects. ALTERNATIVE 2 - Under this alternative, the managed pool would not share water shortages during dry years. Consequently, more water would be available downstream during extremely dry years when water shortages result. In Alternatives 1 and 3, the reserved pool would have to share in the shortages, thus further reducing base flow during critical low flow f1eriods. Thus, Alterna.tive 2 may provide additional proteajon during relatively rare f1eriods of extreme water shortage. This circumstance is expected to occur infrequently, so the overall effect on the aquatic environment and wildlife species dependent on it would be relatively minor. ALTERNATIVE 4 (No Action) - The imf1lementation of this alternative would return release management to the 20, 50, 18 cfs regime under which McPhee Dam was operated for the frn 6 or 1 years of operation. As discussed in the Aquatic Resources section, that operating regime has a decidedly negative affect on the aquatic envirorunent overall, panicu]arly during "dry" and "nonnal" years, when base flow is maintained at an inadequate level year-round. Because an extended "dry" period could have serious consequences for both fish and invertebrate stream biota, species dependent on aquatic biota as a food source would also likely be adverseiy affected. E. WETLAND AND RIP AIDAN I. AFFECTED ENVIRONMENT WETLANDIRIPARIAN VEGETATION COMMUNITIES The Dolores River supports several types of wetland/riparian vegetation communities downstream of McPhee Dam. These include mature cottonwood forests, riparian shrub!ands, and emergent wetlands.. Due to the relatively narrow floodplain in this pOrtion of the Dolores River, these communities generally occur in narrow bands along the river banks and in old overflow channels and oxbows. . COTIONWOOD fORESTS Narrowleaf cottonwood (PoDulus aneustifolia) forests are common along the Dolor., River downstream of McPhee Dam. Narrowleaf cottonwoods form an open to dense overstory .with a variety of understory shrubs, grasses, and forbs. Understory shrubs and grasses cm include the followinll.5pecies: Skunkbush (Rhus trilobatal Desert olive (Forestiera neomcxic31la) 28