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606 1996, Colorado pikeminnow were stocked near Shiprock and Mexican Hat (River Miles 148 and 607 53) and at least some of these are surviving in the river (Ryden. 2000). 608 Habitat of the fish in the San Juan River includes a complex mix oflow-velocity habitats such as 609 eddies, pools, and backwaters adjacent to swifter run and riffle habitats. A natural hydrograph 610 (high spring flows, lower base flows) is important in maintaining the habitat and one of the main 611 effects of Navajo Reservoir under historic operations has been to reduce high spring flows while, .,:, 612 increasing base flows. Miller and Ptacek (2000) and Holden (1999) discuss habitat types 613 seasonally used by the pikeminnow and should be referred to for specific information. Habitat 614 types used varies seasonally. During the pre-spawn period, pikeminnow use mainly slower 615 velocity habitats, including mouths of tributaries such as the Mancos River. During spawning, 616 higher velocity and often complex habitat areas are used. Following spawning the fish move into 617 simpler habitat complexes such as runs and pools; and runs provide fall and winter habitat 618 Juvenile fish prefer shallow, low velocity habitats including backwaters, shoals, eddies, and 619 pools. These low velocity habitats comprise less than 15 percent of the rivers' habitats (Bliesner 620 and Lamarra, 1996). 621 Loss of habitat, competition from non-native fish, water quality problems, and migration barriers 622 are all be factors in the fishes' decline. Reductions of water temperatures due to the operation 623 of Navajo Reservoir may also be a factor in reducing the range of the species, and habitat in the 624 lower river was lost when Lake Powell was filled. Larval fish that drift into Lake Powell may all 625 be lost due to predation. 626 Non-native fish are common throughout the critical habitat reach and include channel catfish, 627 carp, fathead minnows, and other species. During monitoring trips on the river in 2000, striped 628 bass were common (SJRBRIP, 200Ib). Striped bass represent a predatory threat to native fish. 629 There are five major diversion structures between RM 142 and RM 178, which impede fish 630 movement to varying degrees (Masslich and Holden, 1996); and this may strongly influence the 631 range of the pikeminnow which is a migratory species. A fish passage has been completed at the 632 Hogback Diversion and one is scheduled for the Public Service Company of New Mexico (PNM) 633 Diversion. 634 There is potential that water contaminants may also affect the fish; these include selenium and 635 PAH's. Further studies are needed to determine if water quality in the main river and in tributary 636 inflow areas are affecting the species. 637 The flow recommendations are specifically designed to create and protect habitats used by the 638 fish (Holden, 1999). Higher spring flows (>10,000 cfs) generate new cobble sources, channel 639 diversity, and provide nutrient loading. Lower peaks provide and maintai~ spawning habitat 640 The proposed operation should meet or exceed recommendations for spring flows. Table 4 641 indicates how the frequency of spring flows are met under the proposed action and No Action 642 alternatives. Overall, the No Action altemative fails to meet the desired frequency and duration 21 .....