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Powell Forecast (USBR)
The operation of Lake Powell and Lake Mead in this April 2018 24-Month Study is pursuant to the December 2007 Record of Decision on Colorado River Interim Guidelines for Lower Basin Shortages and the Coordinated Operations of Lake Powell and Lake Mead (Interim Guidelines), and reflects the 2018 Annual Operating Plan (AOP). Pursuant to the Interim Guidelines, the August 2017 24-Month Study projections of the January 1, 2018, system storage and reservoir water surface elevations set the operational tier for the coordinated operation of Lake Powell and Lake Mead during 2018.
Consistent with Section 6.B of the Interim Guidelines, Lake Powell’s operations in water year 2018 will be governed by the Upper Elevation Balancing Tier. With an 8.23 million acre-feet (maf) release from Lake Powell in water year 2018, the April 2018 24-Month Study projects the end of water year elevation at Lake Powell to be above 3,575 feet above sea level (feet), and the end of water year elevation at Lake Mead to be below 1,075 feet. Therefore, in accordance with Section 6.B.4 of the Interim Guidelines, Lake Powell operations will shift to balancing releases for the remainder of water year 2018. Under Section 6.B.4, the contents of Lake Powell and Lake Mead will be balanced by the end of the water year, but not more than 9.0 maf and not less than 8.23 maf shall be released from Lake Powell. Based on the most probable inflow forecast, this April 24- Month Study projects a balancing release of 9.0 maf in water year 2018; however, the actual release in water year 2018 will depend on hydrology in the remainder of water year and will range from 8.23 to 9.0 maf. The projected release from Lake Powell in water year 2018 will be updated each month throughout the remainder of the water year.
Consistent with Section 2.B.5 of the Interim Guidelines, the Intentionally Created Surplus (ICS) Surplus Condition is the criterion governing the operation of Lake Mead for calendar year 2018.
The Interim Guidelines are available for download at: https://www.usbr.gov/lc/region/programs/strategies/RecordofDecision.pdf. The 2018 AOP is available for download at: https://www.usbr.gov/lc/region/g4000/aop/AOP18.pdf