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I I I I I I I I I I I I I I I I I I I Experimental stocking of Colorado pikeminnow in the San Juan River began in 1996. Between 1996 and 2000, approximately 832,000 larval Colorado pikeminnow were stocked in the San Juan River. About 727,000 were stocked between IL~1141 and 158. The balance was stocked at R.\tI 52 (Ryden, 2003). Initial retention was encouraging and over winter survival was high (spring captures = 62.5-62.7% of fall captures) and survival between age one and age two based on recapture rates neared 100 percent (Archer et al. 2000). As a result of this initial success an augmentation plan began in 2002 and calls for stocking and monitoring 300,000 age-O Colorado pikeminno\v at R.vI 180.2 and R.vl 158.6 for seven years (Ryden and ~kAda 2003). In addition to augmentation, ongoing recovery efforts include mimicry of a natural hydro graph, adult and larval fish monitoring, habitat and water quality monitoring and c{.mtrol of non-native spe-eies and removal of migration barriers. In 2003, the fish passage at the P1\"Nl weir was finished and put into operation. During the summer of 2003, 9 Colorado pikeminnow used the fish passage (Lapahie, 2004). One of the goals of the SJRIP is the expansion of range of Colorado Pikeminnow and removal of barriers to migration (SJRIP 1995). The removal of the Cudei diversion dam and construction of fish passage at the Hogback diversion dam in 2001 and the documented use of the fish passage at the PI\xf \\-eir has provided opportunity for and documented use of this upper portion of the river by Colorado Pikeminnow, an important step toward recovery. The NG\VSP has potential to adversely affect Colorado pikeminnow. Specifically, the proje-et may entrain larval Colonido pikeminnow into the diversion structure, thus adversely affe-eting recruitment of Colorado pikeminnow spawning above the proposed intake. \vltile no spawning sites have been documented above the proposed diversion, the quality of gravel bars suggests spawning potential between the diversion and RLvl 180 (Bliesner 2003). Spa\vning has been documented benveen :R,.\r1129.8 and &"\11133.4 (Ryden, 2000a) while drift data suggest spawning likely occurred at a location somewhat below R..\tll28 (Platania et al. 2000). Given the known range of spawning, the availability of spawning habitat above the diversion and a relatively uniform distribution of available spawning habitat benveen &\<1 128 and R.1\tl 180, about 25 percent of Colorado pikeminnow spawn could occur above the proposed intake (IUv1l 67) at some point in the future (13 of 52 miles above the diversion). If spawning habitat below RM 128 exists as the drift data suggests, then something less than 25 percent of the spa\\;n would be above the diversion. Based on spa\yning dates in the San Juan River, larvae typically enter the drift from mid-July to ~'1id-August (Platania et al. 2000) and are passive in the drift for 3 to 6 days after emergence (Dudley and Platania 2000). Therefore, larval Colorado Pikeminnow spawned above the diversion would be subject to entrainment for about 35 to 40 days. Flows during this period average about 1,500 cfs at the Farmington gage (1993-2003; USGS 2003). The proposed intake will diven about 4 percent (59 cfs) of the total river flow during peak pikeminnow drift. Colorado pikeminnow exit the drift at 0.55 inches and will not be excluded by a 3/32 inch screen (Platania et al. 2000). Thus, we estimate that about 4 percent of larvae spawned above the intake \,,'ill be subject to entrainment. Since only 25% or less of the spawn is expected above the diversion, the net loss is expected to be less than 1 percent of all Colorado pikeminnow larvae produced in the San Juan River. There are no other adverse effects. BIOLOGICAL ASSESSMENT NAVAJO GALLUP WATER SUPPLY PROJECT September 3, 2004 Page 36