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~~cond w<IS in clre sf'ring of 1 99J. ilJ1d occurred ~s a result of a dd.1Y ;n repairs !o !h~ m~;n Dulle! works. 11le spillway is not considered to be an acceptable me:ms of releasing water because il can only be used when the reservoir is full. Releases through the spillway are also detrimental to the downstream tishery because of the possibility cf escapement of fish from the reservoir. River Outlet Works. TIte river outlet works is loealed in the left abutment of the d:ll1l. TIle minimum discharge capacity of the river outlet works is 200 cfs. the maximum is 5,000 cfs. Water released from the main outlet works, like thaI released from the bypass (described below), is at the lowesttemperature of allY in the reservoir for most of the year. Bvtiass - The bypass was installed to route releases around the river oUllet works. It was incorporated inlo the dam structure and remains operational. The bypass cOllsists of a 20-inch diameter pipe with a 14-inch valve. TIle inlet is near the bottom of the reservoir at approximately the same elevation as that of the main outlet works. Its maximum discharge capacity is directly dependent solely on the elevation of the reservoir, since the valve can only be either fully open or closed. The other outlets can release varying amounts of water. At maximum reservoir elevation, approximately 70 cfs may be released from the bypass structure. However, at minimum reservoir elevation (the top of the inactive sorage pool) only some 30 cfs may be released from the bypass. Because the bypass inlet is near the reservoir bottom, as is that for the river outlet works, it provides the coolest water possible for most of the year. Selective Level Outlet Works and Power Plant - The Selective Level Outlet Works (SLOW) consists of a vertical intake pipe with inlets at three different elevations in the reservoir, 6,891.75 feet, 6,865.75 feet and 6.840 feet. The purpose is to release water of different temperatures, which would allow flexibility to mix varying amounts of water from different reservoir levels to attain an optimum release temperature for the downstream fishery. This goal may be attained for part of the year, but during the summer, the lowest intake does not normally reach the cooler water at the lower elevations of the reservoir. As it was originally designed, water would be routed Eram rhe inlet(s) through a 24-inch pipe with a 20-inch valve. It was designed for a maximum discharge capacity of 200 .cfs. Modification of the system to conduct warer through a penstock inside the ri",er outlet works to the hydroelectric plant reduced this maximum discharge capacity. Vibration problems discovered during testing limit the maximum discharge capacity to 75-78 cfs. 2. ENVIRONMENTAL CONSEQUENCES WATER QUALITY (CHEMICAL) ALL ALTERNATIVES - These alternatives would have no effect on the chemical constituency of the walet, because no contaminants or chemical constituents would be added to or deleted from the water. In addition, the volume of additional water would not be sufficient to dilute or concentrate the chemical constituents found in the river downstream from the dam. WATER QUALITY (TEMPERATURE) AL TERNA TIVE I (proposed Action) . This alternative would result in mainlenan.. of a suitable water temperature to support trout to the Br.ulfield Bridge vicinity. Beyond that point, the volume of additional wacer would have little or no effeCl on water lemperalurC3. The lemperature of.the OolorC3 River at the Dove Creek pump plant is often the same temperature or cooler than that at Br.ulfield Bridge, due mainly to stream morphology and shading in the cattyon. Within physical limits, the various darn outlets would be selected or mixed to provide suitable water temperature for release. The decision as to' how much waleT of what lemperature should be released at a given time to optimize the water temperature of the downstream trout fishery would be made based on the recommendations of an interagency tearn of biologists. 32