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<br /> <br />... Section 2 <br /> <br />Background <br /> <br />2.2.5 GCD OPERATIONS <br /> <br />2.2.5.1 OPERATING CRITERIA To protect downstream resources, Reclamation <br />implemented operating procedures in February 1997, to operate OCD in a restricted mode. <br />The operating procedures include release criteria which limit the maximum release rate to <br />25,000 cfs, reducing the useable capacity at OCD to about 1,000 megawatts at current <br />reservoir levels,2 Minimum releases of 5,000 and 8,000 cfs (depending, on the time of day) <br />must be maintained, and ramp rate restrictions are in effect as well. Down ramp rates are <br />limited to 1,500 cfs per hour and up ramp rates are limited to 4,000 cfs per hour to avoid <br />the rapid rise and fall of water levels downstream from OCD. Finally, the maximum daily <br />(24-hour) change in water release is limited to 5,000 cfs/day to 8,000 cfs/day, depending <br />on the monthly release volume. Limiting the maximum allowable release results in a lower <br />available on-peak capacity, while restricting ramp rates and the allowable daily change in <br />flow, reduces operating flexibility, or the ability to follow hourly and instantaneous changes <br />in electrical load. Increasing minimum flows also reduces the total value of energy <br />generated by forcing increased off-peak releases and limiting the ability to make high-cost, <br />on-peak economy energy sales from low-cost, off-peak purchases. The overall effect of the <br />interim operating criteria is to reduce the amount of operable hydroelectric capacity and <br />energy generation during on-peak hours, and increase the amount of energy generated off- <br />peak. <br /> <br />The operating criteria also outline operating procedures to address certain emergency and <br />system regulation requirements, These procedures allow water releases to exceed the flow <br />restrictions imposed by the operating criteria. <br /> <br />The degree to which Western can use hydroelectric generation to respond to emergencies <br />and system regulation requirements is an important consideration in the Replacement <br />Resources Process, because it influences the characteristics of replacement power. <br />Because capacity from OCD can be used to serve load under emergency circumstances, <br />Olen Canyon has a higher useable on-peak capacity, albeit for short periods of time, <br />Replacement power can therefore be obtained at lower cost on the bulk power market than <br />would be the case in the absence of these emergency and system regulation procedures. <br /> <br />2.2.6 GLEN CANYON DAM EIS <br /> <br />In July 1989, the Secretary of the Interior announced that the Bureau of Reclamation would <br />prepare an EIS on the effects of OCD operation on the downstream environment under <br />guidelines established by the National Environment Policy Act of 1969, The study area in <br />the OCD-EIS was the Colorado River corridor from OCD through the Orand Canyon <br />down to Lake Mead, The following alternative flow regimes were identified: <br /> <br />2-6 <br /> <br />Western Area Power Administration <br /> <br />March 1998 <br />