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I I I I I I I I I I I I I I I I I I I The outlet gates are used primarily when releases are 50 cfs or greater, to provide water for irrigation which occurs from late April until mid-October. During the winter months water is released to satisfy senior water rights and for fishery flows the river below the dam. The primary senior water user below the dam is the city of Durango which can divert up to 8.9 cfs; therefore, the winter time water demand is about 9 cfs or less. The winter releases are made through a small bypass pipe which begins upstream of the main gates and exits 26 feet below the gates. See Figure 6.1 for piping details. Depending upon the reservoir water level, uncontrolled releases through the bypass could be around 20 cfs, which is considerably greater than the demand. Thus, smaller diameter orifices are bolted to the exit end of the pipe to reduce the releases to about 9 cfs to 13 cfs. Generally, two orifices are interchanged to attain the desired release based upon the reservoir water elevation. The gate chamber has a 23-foot horizontal diameter and is 16 feet high at the crown. See Figure 6.1. Access to the gate chamber is through a 7. 5-foot diameter vertical access shaft 80 feet to the right of the gate chamber. The shaft is about 200 feet high with a gate house at the top and a chamber similar in size to the gate chamber at the bottom. The bottom of the shaft and the gate chamber are connected by a 50-foot long, 7-foot high tunnel. A ventilation system brings air from the gate house, down the shaft, to the gate chamber. An elevator and staircase are installed in the shaft for access. The horizontal dimensions of the inside of the elevator are 1. 9 ft by 3 ft. The elevator has a travel distance of 210 ft and a live load capacity of 1000 Ibs. The gate chamber can also be diameter manhole between the chamber accessed through and the horseshoe a two-foot tunnel, 7.0-2