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847 years after the dam was closed in the mid-1960's. It is now rarely collected, indicating that much of its 848 reproductive habitat was lost to the reservoir. 849 Habitat used most commonly are pools with some type of cover and spawning occurs in pool-riffles or 850 in riffles upstream from pools (Propst, 1999). Loss of habitat through flow depletion or channel 851 modification, and competition from non-native fish are probably factors in their low populations in the 852 San Juan. Olson (1962) attributed low numbers to changes in water temperatures below Navajo Dam 853 and due to early efforts to remove nongame fish from the river. 854 The more natural hydrograph downstream from Farmington may benefit these species by reducing 855 non-native fish that compete and by providing more natural habitat conditions. Upstream from 856 Fannington, adverse effects are possible because of reduced habitat associated with lower summer 857 flows and possibly by water quality declines; however, the fish is very uncommon in this area. 858 New Mexico silversDot and San Juan checkersDot butterflies 859 These insect species are native species with limited distribution. Populations are affected by habitat 860 losses and in some cases collection. The proposed action should not affect these species, although it 861 would provide a more natural river and floodplain condition which may benefit them. 862 San Juan tiger beetle 863 Tiger beetles are common but some species have limited distribution. Habitat includes sandy areas, 864 including riparian areas. As a native species, the San Juan tiger beetle would be expected to benefit 865 from a more natural riparian area; the proposed plan should have either a neutral or beneficial effect. 866 Gunnison sage grouse 867 The Gunnison sage grouse currently occurs in eight isolated populations in western Colorado and 868 southeastern Utah. The species has been in decline, presumably due to habitat loss and fragmentation. 869 Habitat includes large expanses of sagebrush with a diversity of grasses and forbs and healthy riparian 870 areas. Existing or potential habitat of this species would not be affected by the proposed reoperation of 871 Navajo Reservoir. 872 Other Species of Concern 873 The Navajo Nation provided a list of species of special concern that included several of the species 874 discussed above, but contained the following additional species: 875 Golden eagle 876 The golden eagle uses a variety of habitats in the San Juan basin including the San Juan River corridor. 877 Nesting occurs on cliffs or large trees. Primary foods include small mammals and carrion although 29