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<br />Chapter II Description of Alternatives 17 <br /> <br />surface is at or above 3,653 feet, the spillways would discharge about 8,000 ftJ/s into the <br />tunnel spillways. The remaining about 17,000 ft3/s would be released from the turbines with <br />this option. This would mean that the bypassed flow would not generate power. No <br />modifications would be needed to the dam for this option to work, but lost power revenues <br />would occur. During the times when warmer water is needed downstream, the radial gates <br />could be opened and warm water could be skimmed off the top reservoir. <br /> <br />By releasing 8,000 ft3/s from the spillway and 17,000 from the turbines downstream, release <br />temperatures at the dam for April, May, June, and July would be 5l.00F, 54.7"F, 60.1 OF, and <br />6L50F (10.70C, l2.50C, l5.60C, and l6.40C), respectively, for a starting elevation 00,653 <br />feet in April. When all the flows are released through the turbines temperatures of 44.3 OF, <br />44.30F, 44.40F, and 44.5 of (6.80C, 6.80C, 6.90C, 7.00C) occur during April to July <br />downstream from the Dam. <br /> <br />There are several potential complications with this proposal. Initial releases may need to be <br />greater than 8,000 ft3 Is to clean debris from the flip bucket. This may cause thermal shock to <br />fish near the dam. Low flows may cause dissolved gas problems if the jet from the flip <br />bucket stays submerged. The ability to control the discharge by adjusting the radial gate may <br />not be very precise using the existing controls. Also, the gate openings would need to be <br />increased as the pool elevation goes below elevation 3,653 feet to maintain 8,000 ft3/s. <br /> <br />The range of operation for this option would be from full pool (elevation 3,700 feet) to about <br />3,653 feet. Below this elevation, the flow from the spillways would decrease until at 3,648 <br />feet; no flow would be released by the spillway in this option. Consequently, all flow would <br />be released through the turbines at about 44.60F or 46.4 OF (7.00C and 8.00C). <br /> <br />Costs associated with this option could be significant. According to the operators each <br />turbine generates about $75,000 of power during each day of operation at 4,000 ft3/s <br />discharge. Power costs based on this rule of thumb would imply that about $150,000/day <br />would be lost by using the spillways and taking two turbines offline. <br /> <br />Proposal No. 2A - Remove top oftrashrack structure and install gate at penstock <br />intake. This proposal meets the objectives of warm water releases at a relatively low cost. It <br />requires the reservoir to be relatively full and would not function every year, but because <br />native fish are long lived and their competitors are not, frequent (annual) warmwater releases <br />are not required. This proposal was determined to be both cost effective and functional. The <br />proposal was brought forward for more detailed cost analysis. The feasibility level cost <br />estimate for this proposal was $15,000,000. This method of temperature control is described <br />in more detail (earlier in this chapter) as the proposed temperature control alternative in this <br />environmental assessment. <br /> <br />Proposal No. 2B - Remove top of trasbrack structure and install gate at penstock <br />intake and install a middle level gate. The appraisal level cost of this proposal is <br />$35,000,000. The benefits of this proposal were similar to proposal No. 2A, but would <br />provide the added flexibility of a mid-level withdrawal. The disadvantages of this alternative <br />over proposal No. 2A were its higher cost and complexity. This proposal is functionally <br />