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<br />1998 report to the RIo Grande Compact CommIssion
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<br />Bureau of ReclamatIOn
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<br />operations, or any other purpose authorized by Federal law, except non-emergency
<br />power generation, dictate othelWise. Significant variation above 50,000 af during the
<br />winter months of October through January requires collaboration and consultation
<br />between the Districts and Reclamation.
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<br />Reclamation's plan for operation of Caballo Reservoir during February 1 through
<br />September 30,1998, was to maintain storage levels within a flexible storage range of
<br />30,000 af, such that, the storage level would not be less than 50,000 af (4,144.95 ft)
<br />and not exceed 80,000 af (4,151.63 ft). These operational procedures will keep more
<br />water in Elephant Butte Reservoir in order to reduce evaporative losses, and at the
<br />same time, provide for sufficient operational hydraulic head at Caballo Reservoir for
<br />irrigation demand releases. The flexible storage range will also serve as a reserve pool
<br />in case releases are interrupted from Elephant Butte Reservoir and will minimize
<br />changes to release rates from Elephant Butte Reservoir. Reclamation and the Districts
<br />agreed to the plan on August 27, 1997, and a final operating plan was distributed on
<br />October 3,1997.
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<br />Caballo Reservoir's operating plan for October 1, 1998 through September 30, 1999
<br />was coordinated with the Districts. On September 18, 1998, Reclamation and the
<br />Districts met to discuss the proposed plan of operation for Caballo Reservoir from
<br />October 1, 1998 to September 30, 1999. The Districts suggested that Caballo
<br />Reservoir could be operated at a lower reservoir storage level to reduce losses due to
<br />evaporation between the two reservoirs. Reclamation analyzed the evaporative
<br />differences between the old plan of a flexible pool (80,000 af to 50,000 at) and a lower
<br />flexible pool storage level (65,000 af to 40,000 at). Reclamation concluded that
<br />approximately 2,000 af due to evaporation could be saved if Caballo Reservoir was
<br />operated at the lower flexible pool storage level. On December 9, 1998, Reclamation
<br />transmitted its final plan of operation for Caballo Reservoir which included the "not to
<br />exceed" 50,000 af target of storage from October 1, 1998 to January 31, 1999, and
<br />operating within a flexible storage band of 25,000 af (minimum 40,000 af total storage
<br />to a maximum 65,000 af total storage) from February 1, 1999 to September 30, 1999.
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<br />Elephant Butte Reservoir Flood Study
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<br />Reclamation completed a study to evaluate the need for a flood control space in
<br />Elephant Butte Reservoir in February 1997. The flood study supported the concept of
<br />an approximate 1 OO-year flood control space of 50,000 af in Elephant Butte Reservoir.
<br />At the Rio Grande Compact Commission's special meeting in September 1998, the
<br />Commission approved recognition of the 50,000 af flood space from April 1 to
<br />September 30 and the 25,000af flood space from October 1 to March 31 each year in
<br />Elephant Butte Reservoir. This storage space will now no longer be considered part of
<br />Rio Grande Project storage for Rio Grande Compact accounting purposes.
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