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, - ROUNDTAIL CHUB The roundtail chub is commonly found throughout much of the Dolores River downstream of McPhee Dam. While populations of this species have declined in . other ri~er basins (most notably in the San Juan River Basin) over recent years, they have persisted in the Dolores River drainage. Apparently tolerant of changes in wide flow variations, management of spills from McPhee Dam may play a far more significant role in maintaining a healthy population of these fish in the Dolores River than do base flows. Since the closure .of McPhee Dam, successful natural reproduction by this species has been verified in the Dolores River (pers. comm. Mike Japhet CDOW, 1994) including 1990 when flow was reduced to 20 cfs, the only time this occurred since the closure of the dam in 1984. Spawning occurred over a wide range of flow conditions over the years indicating base flow may not be a significant factor for successful spawning. High spring flows, of sufficient magnitude, duration and timing may be much more important in providing suitable conditions for successful reproduction by this species than do the magnitude of post run-off base flows. unfortunately, although successful spawning has been verified, the extent of recruitment of young-of-the-year chubs to spawning age is not known. While chub flow tolerances are not well understood in the Dolores River, extreme low flows (20 cfs) may limit young-of-the-year habitat and survival for this species and should be avoided (Valdez, et al., 1992). Under the proposed pool management strategy, such extreme low flow conditions would be avoided. Consequently, it is unlikely any of the proposed pool management alternatives would adversely affect this species in the Dolores River. FLANNBLMOtlTH SUCKER The flannelmouth sucker, unlike the roundtail chub, is considered abundant in the Upper Colorado River Basin. While this species is relatively rare in the Lower Colorado River Basin due to massive habitat alterations, it has not been subjected to the same level of impact in the upper basin. This species is considered to be common in the Dolores River. Successful natural reproduction by this species in the Dolores River has been verified since the closure of McPhee Dam (pers. comm. Mike Japhet, CDOW, 1994). There is not sufficient information available at this time regarding recruitment of young-of-the-year suckers to adulthood. As described above for the roundtail chub, extreme low flows associated with the No Action Alternative might have an adverse affect on this species. As with other Colorado River endemic fish species, the timing, magnitude and duration of spring flushing flows (spill management) may be significant in maintaining this species in the Dolores River. Since extreme low flows are avoided after spawning and through the fall with all of the pool management alternatives, none of these alternatives should effect this species in the Dolores River. SAN JUAN RIVER The Dolores Project was constructed and is operated to divert water from the Dolores River basin for beneficial use in the San Juan River basin. However, the project is not yet fully developed and much of the planned use of project water is not yet occurring. Project water not consumptively used in the San Juan Basin, would flow in to the San Juan River through three drainages. The majority of water not consumptively used would enter the San Juan River at the confluence of McElmo Creek, near Aneth, Utah. Some water would also return to the San Juan River via Navajo Wash/Mancos River and some water would be conveyed by Montezuma Creek. Historical return flows from non-project diversions are included in the USGS flow records of the San Juan River at Bluff, Utah. These flow data were part of the existing baseline conditions described in the Animas La Plata Project Biological Opinion (USFWS, 1991). In addition, Project return flows were 14