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002481 physiographic and engineering data pertaining to reservoirs, dams, and river reaches. Based on a review of the data, .u.J ~'.!W~M<""'JJl1rf1~_:~: .' "M"~l~l'" l~IM,.~iDBth,~4.Wl_~~~hJW~ 'B.~:.i'~~~~',ef_~j~~e ~1~'~)_fRIIIB'tiDtm.~~~1IM. Additionally, one or more temperature recording devices on the mains tern of the Gunnison and certain major tributaries above Blue Mesa Reservoir (e.g., Lake Fork, Cebolla, Willow, etc.) would be useful for development and calibration of a Blue Mesa temperature model. Data Analvsis. The primary objective of phase I of this project was to determine whether or not modifications to the Aspinall Unit could result in warmer water temperatures downstream near Delta. Before undertaking a substantial model development program, the Recovery Program asked that we undertake a preliminary analysis of the data with the pIlIpOSe~~l ~~j~'~s.j'.i.........rmer~ t "j~mr~fic~;__-"'~g ~~~at~*hf.tlt'er'Of~i~'~~fl. Our scope for phase I was limited to some straightforward processing of data for visualization and preliminary statistical analyses. Nevertheless, the following conclusions can be drawn: 1. 81x ll._.....iIi8t.~ti~1~:k"~~~i()ns, _.....~~~,~;_W<<\.._~. 2. Blue Mesa Reservoir is the primary cause of cold-water releases from the Aspinall Unit. C;ryst~"~~;~W~~~~~;1~se'9ti~'~"'-.'.~~'" "_~"~Jl~~"~~,,,,~;.:'''''*'_lj)tf~. 3. Warmer water is physically available in Blue Mesa, and could be released downstream with a TCD. Models of all three reservoirs would be useful in determining the impacts of such a structure on the thermal regimes of the reservoirs. 4. Tributary inflows do impact stream temperatures at Delta, but not with a frequency or magnitude to render potential reservoir control ineffective. 5. Warmer releases from Crystal would result in warmer river temperatures at Delta. Generally, release temperatures from Crystal would need to be increased about 3 Oc to warm the river at Delta by 2 oc. 6. Stream temperatures at Delta show a strong statistical correlation to release temperatures and atmospheric conditions; thus, a statistical model could potentially be used in lieu of a more costly physically-based model of the river. Constraints. We focused this work predominantly on questions of whether or not it would be physically possible to obtain warmer stream temperatures near Delta through operational or structural modifications to the Aspinall Reservoirs. However, a significant consideration of any proposed change to the system would necessarily involve non- physical factors including (but not limited to) lost hydropower revenue, state and federal reserved water rights, interstate and international compacts, minimum instream flows,