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CHAPTER 2 ALTERNATIVES INCLUDING PROPOSED ACTION Alternative B The AB Lateral Facility would be developed to a capacity of 1,135 cubic feet per second (ft'/s). Irrigation demands were assumed to equal historically recorded diversions. Minimum instream flow in the Gunnison River was assumed to be 300 ft'/s during all months of the year. Alternative C The AB Lateral Facility capacity and minimum flow for this alternative are the same as those values for alternative B (1,135 ft'/s and 300 ft'/s, respectively). However, the Gunnison Tunnel capacity would be increased to 1,300 ft'/s. Alternative E This alternative proposes developing of the AB Lateral Facility to a capacity of 950 ft'/s, without alteration of the Gunnison Tunnel. The minimum instream flows were assumed to be 300 ft'/s for all months of the year. Alternative F This alternative would have a design configuration identical to alternative B; however, it would be operated differently. During winter months, if ice buildups occurred at locations which would threaten existing structures or habitat, diversions would be reduced to increase flows in the Gunnison River. For purposes of modeling water flows, this amount has been assumed to equal 600 ft'/s for 7 days each month, which is an average monthly increase. of 68 ft'/s in January and 75 ft'/s in February. A further operational change included in alternative F is represented by providing through the South Canal an additional 1,000 acre-feet of water in the Uncompahgre River upstream from the tailrace in the months of August and September. This flow would be used in the river as directed by the Colorado Division of Wildlife (CDOW), should a fishery be developed in the Uncompahgre River. For purposes of modeling water flows, this amount has been estimated at an average of 8 ft'/s in each of the 2 months. 2 - 2