Albuquerque Area Office

Water Operations Group

Annual Operations Plan - Calendar Year 2001

Caballo Reservoir: According to Court Order No. CIV-90-95- HB/WWD of October 17, 1996, which resulted from a negotiated settlement with the U.S. irrigation districts, the Caballo Reservoir storage level is targeted not to exceed 50,000 af (4,146.11 ft) from October 1 to January 31 of each year, unless flood control operations, storage of water for conservation purposes, regulation of releases from Elephant Butte Dam, safety of dams purposes, emergency operations, or any other purpose authorized by Federal law, except non-emergency power generation, dictate otherwise. Significant variation above 50,000 af during the winter months of October through January requires collaboration and consultation between the districts and Reclamation.

Reclamation's plan for operation of Caballo Reservoir during October 1, 2000 through September 30, 2001 was coordinated with the districts by letter transmitted on November 15, 2000. It also reflects accommodations for the Elephant Butte turbine runner replacement program. Under this plan, Reclamation would raise Caballo Reservoir to a maximum storage level of 112,000 af (4,157.89 ft) by late February, 2001 and gradually allow the reservoir storage to decrease throughout the irrigation season to a low point of approximately 42,000 af (4,143.98 ft) by the end of August 2001. Having higher storage levels earlier in the irrigation season allows Reclamation to:

Reduce evaporative losses between Elephant Butte and Caballo Reservoirs
Provide sufficient operational hydraulic head at Caballo Reservoir for irrigation demand releases
Serve as a reserve pool in case releases were interrupted from Elephant Butte Dam and minimize changes to release rates from Elephant Butte Dam
Compensate for loss in discharge capacity from Elephant Butte Dam power plant due to the turbine runner replacement program.

Reclamation will draw Caballo Reservoir down to the trash rack structure level (6,600 af at elevation 4,128.53 ft) by the end of September 2001 to allow an inspection of the outlet works of Caballo Dam during October and November 2001. The last time this inspection was conducted and the reservoir drawn this low was 1981. Reclamation currently is preparing an environmental assessment of this special drawdown operation at Caballo Reservoir. The reservoir will be raised up to its normal winter operating range in December 2001.

In January 2000, Reclamation proposed a temporary restriction on the Caballo Reservoir pool level due to safety concerns of operating the spillway gates under static and dynamic loading. Under this restriction, Reclamation will not be allowed to exceed the elevation of 4,161.00 ft (the spillway crest) or 133,428 af for normal conservation storage operation. Reclamation will allow a functional flood control pool (100,000 af) from elevation 4,161.00 ft to 4,173.17 ft. This operating restriction was made official at the March 23, 2000 Rio Grande Compact Commissioners' annual meeting in El Paso, TX. The restriction will be eliminated when the spillway gates are repaired.

Presently, Reclamation anticipates final design drawings to be completed in June 2001 to repair and modify the spillway gates' radial arms. Reclamation will begin the repair work in the fall of 2001 and should complete repair work on the spillway gates in 2002. Once repair work is complete, the temporary reservoir restrictions will be removed.

The peak storage for Caballo Reservoir of 115,100 af at an elevation of 4158.36 feet has already occurred on March 9, 2001. The highest storage ever recorded at Caballo Reservoir was 346,570 af at an elevation of 4182.06 feet, just 0.06 foot above the top of the flood pool elevation of 4,182.00 feet. This high storage occurred March 4, 1942. The lowest storage at Caballo Reservoir during 2001 is projected to occur from October 10 thru October 14 at 5,905 af at an elevation of 4,128.00 feet. The average storage at Caballo Reservoir during 2001 will be 57,554 af at an elevation of 4,147.92 feet. Caballo releases for 2001 are estimated to be 775,000 af.

[Caballo Reservoir]