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30 Having reached consensus that altered flows were the number one issue on the San Juan River, the Biology Committee agreed on the following major assumptions/ hypotheses: 1. Late spring and early summer flows are important for spawning and recruitment (flow and temperature) of Colorado squawfish. 2. Seasonally flooded lowlands may be important for razorback sucker spawning. 3. The abundance of native species is directly related to predation and competition by nonnative species. 4. Elimination of instream migration barriers would increase access to spawning areas and decrease impacts on drifting larvae of Colorado squawfish and razorback sucker. 5. ~he San Juan River during certain hydrological conditions appears to have suitable habitat for successful spawning, nursery, and rearing of native species. 6. Various life history stages of the native fish species may be adversely affected by water quality impacts on the San Juan River. 7. Historic flow conditions (discharge volume, timing, duration, water quality, and habitat availability) in the San Juan River were good for native fish, including the rare and endangered fish species. 8. Operation of the Navajo Dam and Reservoir to mimic a natural historic hydrograph will be physically and biologically beneficial. 9. A natural hydrograph with large spring peaks, a gradually declining/ descending limb into early summer, and low stable flows through summer, fall, and winter may be the best flow/habitat conditions for rare and endangered fishes in the San Juan River while maintaining the geomorphology of the river channel. 10. High spring peaks with a gradually descending limb may be necessary for the formation and maintenance of important nursery habitats in the San Juan River. 11. Operation of the Navajo Dam and Reservoir for native species can be accomplished without negative impacts on the tailwater sa1monid populations and fishery (under current depletion levels).