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<br />GJ2~34 <br /> <br />Emerl!ency Exception Criteria - Normal powerplant operations will be altered temporarily to <br />respond to emergencies. These changes in operations typically would be of short duration (usually less <br />than 4 hours) and would be the result of emergencies at the dam or within the interconnected electrical <br />system. Examples of system emergencies include: <br /> <br />4. Insufficient generating capacity <br />5. Transmission system: overload, voltage control, and frequency <br />6. System restoration <br />7. Humanitarian situations (search and rescue) <br /> <br />Flood Frequency Reduction Measures - The frequency of unanticipated flood flows in excess of <br />45,000 cfs will be reduced to no more than I year in 100 years as a long-term average. This will be <br />accomplished initially through the Annual Operating Plan process and eventually by raising the height <br />of the spillway gates at Glen Canyon Dam 4.5 feet. <br /> <br />Habitat Maintenance Flows - Habitat maintenance flows are high steady releases within powerplant <br />capacity (33.200 cfs) not to exceed 14 days in March, although other months will be considered under <br />the Adaptive Management Program. Actual powerplant release capacity may be less (than) 33,200 cfs <br />under low reservoir conditions. These flows will not be scheduled when projected storage in Lake <br />Powell on January I is greater than 19,000,000 acre feet, and typically would occur when annual <br />releases are at or near the minimum objective release of 8,230,000 acre-feet. Habitat maintenance <br />flows differ from beach/habitat-building flows because they will be within powerplant capacity, and <br />will occur nearly every year when the reservoir is low. <br /> <br />BeachlHabitat-Buildinl! Flows - These controlled floods will occur as described in the EIS (steady <br />flow not to exceed 45,000 cfs, duration not to exceed 14 days, up-ramp rates not to exceed 4,000 <br />cfslhour, and down-ramp rates not to exceed 1,500 cfslhour) except instead of conducting them in <br />years in which Lake Powell storage is low on January I, they will be accomplished by utilizing <br />reservoir releases in excess of powerplant capacity required for dam safety purposes. Such releases are <br />consistent with the 1956 Colorado River Storage Project Act, the 1968 Colorado River Basin Project <br />Act, and the 1992 Grand Canyon Protection Act. <br /> <br />/s/ Bruce Babbitt <br />Secretary of the Interior Date <br /> <br />(Feb 24 1997) <br /> <br />15 <br />