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184 VALDEZ AND MUTH Wildlife Service 1997) provides guidance on best stocking strategies. In 1999, about 1,000 Colo- rado pikeminnow were captured from age-O fish stocked in 1996 and 1997 (Archer et al. 2000). To date, about 10,850 subadult and adult razor- back sucker have been stocked in the San Juan River. Larval razorback sucker, which have been found in the river for the last 7 years, indicate that previously stocked fish are surviving and spawn- ing at separate locations (Ryden 2000). Since 2002, over 668,000 juvenile Colorado pike-min- now have been stocked in the San Juan River, and about 300,000 are scheduled to be stocked in fall 2005. Survival of stocked fish provides encouraging prospects for establishing populations of razorback sucker and Colorado pikeminnow in the San Juan River. Protection, management, and augmentation of habitat.- This element involves identifYing impor- tant reaches of the San Juan River for different life stages of the endangered fishes by mapping current conditions, determining relationships between flow and habitat, and determining flow needs. Flow rec- ommendations for the San Juan River have been developed (Holden 1999) and provide flow crite- ria for flushing of sediments and channel reshap- ing, adult and juvenile habitat, and nursery habitat for Colorado pikeminnow and razorback sucker. A final EIS and biological opinion on operation of New Mexico's Navajo Dam and Reservoir to imple- ment the San Juan River flow recommendations for endangered fish are slated for completion in 2005. The proposed preferred alternative in the EIS will fully meet the flow recommendations. The biologi- cal opinion will address the issue of "ongoing ef- fects" of reservoir operations. Another impottant component of habitat aug- mentation is providing fish passage around migra- tion barriers (Masslich and Holden 1996). The Cudei Diversion has been removed, and the Hogback Di- version was modified with a rock channel to provide non-selective fish passage. The Public Service Com- pany of New Mexico (PNM) Weir was fitted with a 122-m selective fish passage, and similar structures are being considered for the Arizona Public Service Company (APS) Weir and the Fruitland Diversion. These modifications will allow for range expansion of Colorado pikeminnow, razorback sucker, and other native fishes. In 2004, 5 razorback sucker and 4 Colo- rado pikeminnow used the fish passage at the PNM Weir. Some of the Colorado pikeminnow that used the ladder in 2003 were collected more than once indicating that there was downstream movement over the PNM Weir by fish released upstream. All razor- back sucker collected in the fish passage in 2004 were captured for the first time. Entrainment of fish in diversion canals is also considered a threat to native fish. In 1996 and 1997, age-O Colorado pikeminnow stocked near the Hogback Diversion, about 4.8 km below Shiprock, New Mexico, became entrained in the diversion canal (Trammell and Archer 2000). The effect of this entrainment to the overall popula- tion is unclear and construction of a fish screen in the canal is planned. water quality protection and enhancement.- This element involves monitoring water quality con- ditions, evaluating historic information, identifYing types and sources of contaminants, investigating changes in water chemistry, and pursuing actions to diminish or eliminate water quality problems that limit recovery. A review of water quality and con- taminants, and a detailed study of selenium and se- lected constituents in water, sediment, soil, and biota in irrigation drainages of the San Juan River subbasin were conducted in 1991-1995. Water quality monitoring is conducted at 5-year intervals. Interactions between native and nonnative fish species.- This element involves determining the dis- tribution and abundance of nonnative fish species, identifYing and characterizing habitats used by non- native fish, discontinuing stocking of nonnative fish species in areas where endangered fish occur, and control of nonnative fishes through removal. Al- though 19 of 26 species in the San Juan River are nonnative (Ryden 2000), native fish comprised 75% of all fish collected in primary channels from 1991 to 1997. The most abundant nonnative species were channel catfish (13%), common carp (9%), and red shiner (2%; Ryden 2000). Small numbers of wall- eye and striped bass were collected in 1995-1997 after gaining access from Lake Powell following in- undation of a waterfall barrier in 1995. Efforts to control nonnative fishes have been