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Gunnison River /Aspinall Unit Temperature Analysis -Phase I Executive Summary, Page-C 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, recreational impacts, and capital costs. A summary of these and other constraints was compiled through numerous conversations with local, state, and federal agency personnel and other parties with an interest in the Recovery Program. A description of the constraints and their potential impacts on the Program's ability to control water temperatures are provided in the report. Modeling Recommendations. Based on the data analysis, we strongly recommend modeling all 3 Aspinall reservoirs, using QUAL-W2, and amulti-variate`statistieal model of Gunnison River temperatures. Stratification of Morrow Point and Crystal Reservoirs is complicated by hypolimnetic inflows from Blue Mesa, and a mechanistic model is needed to predict changes in stratification due to a TCD. Results from these model outputs in phase II would answer several questions, including: 1. Would a TCD at Blue Mesa result in warmer release temperatures at Crystal? 2. If so, how much warmer would they be? 3. Would these warmer release temperatures translate into warmer river temperatures in the area around Delta? 4. What are the benefits of a fixed versus variable height withdrawal structure? 5. How would a TCD impact the thermal structure of the Aspinall reservoirs? Hydrosphere Resource Consultants