Click the link to read the study (and check out the operating plans for the Colorado River system reservoirs) on the Bureau of Reclamation website:
June 15, 2026
The operation of Lake Powell and Lake Mead in the June 2026 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),1 the Supplemental Environmental Impact Statement for Near-term Colorado River Operations Record of Decision (2024 Interim Guidelines SEIS ROD),2 and reflects the 2026 Annual Operating Plan (AOP). Pursuant to the Interim Guidelines, the August 2025 24-Month Study projections of the January 1, 2026, system storage and reservoir water surface elevations set the operational tier for the coordinated operation of Lake Powell and Lake Mead during 2026.
The August 2025 24-Month Study projected the January 1, 2026, Lake Powell elevation to be less than 3,575 feet and at or above 3,525 feet and the Lake Mead elevation to be at or above 1,025 feet. Consistent with Section 6.C.1 of the Interim Guidelines, and Section 6.E of the 2024 Interim Guidelines SEIS ROD, the operational tier for Lake Powell in water year (WY) 2026 is the Mid-Elevation Release Tier and the water year release volume from Lake Powell was originally projected to be 7.48 million acre-feet (maf). Further, given the hydrologic variability of the Colorado River System and potential for declining reservoir conditions, Section 6.E of the 2024 Interim Guidelines SEIS ROD allows for Lake Powell’s release in WY 2026 to be less than 7.48 maf. Consistent with Section 6.E of the 2024 Interim Guidelines SEIS ROD, Reclamation will consider all tools that are available during the interim period to avoid Lake Powell elevation declining below 3,500 feet.
To protect a target elevation at Lake Powell of 3,525 feet, adjustments to Glen Canyon Dam monthly volume releases for the months of December 2025 through April 2026 were implemented in the December 2025 24-Month Study, reducing the release volume for these months by 0.598 maf. As historically dry conditions persisted in WY 2026 and reservoir conditions were projected to decline below 3,500 feet at Lake Powell, the Department of the Interior implemented an action under Section 6.E of the 2024 Interim Guidelines SEIS ROD by reducing Lake Powell’s annual release from 7.48 maf to 6.00 maf in WY 2026.3 This action was taken in conjunction with the 2026 Drought Response Operations Plan which will release between approximately 660,000 acre-feet to 1.00 maf of additional water from Flaming Gorge reservoir to Lake Powell by April 2027.4 The May 2026 Most Probable 24-Month Study reflects a 1.00 maf Drought Response Operations release.
The August 2025 24-Month Study projected the January 1, 2026, Lake Mead elevation to be below 1,075 feet and above 1,050 feet. Consistent with Section 2.D.1 of the Interim Guidelines, a Shortage Condition consistent with Section 2.D.1.a will govern the operation of Lake Mead for calendar year (CY) 2026. In addition, Section III.B of Exhibit 1 to the Lower Basin Drought Contingency Plan (DCP) Agreement will also govern the operation of Lake Mead for CY 2026. Lower Basin projections for Lake Mead take into consideration additional conservation efforts under the DCP and the Lower Colorado River Basin Conservation and Efficiency Program (LC Conservation Program).
Current runoff projections into Lake Powell are provided by the National Weather Service’s Colorado Basin River Forecast Center. The observed unregulated inflow into Lake Powell for the month of May was 0.383 maf or 18% of the 30-year average from 1991 to 2020. The June 2026 unregulated inflow forecast for Lake Powell is 0.170 maf or 7% of the 30-year average. The 2026 April through July unregulated inflow forecast for Lake Powell is 0.950 maf or 15% of average. The WY 2026 unregulated inflow forecast for Lake Powell is 3.40 maf or 35% of average.
In this study, the CY 2026 diversion for Metropolitan Water District of Southern California (MWD) is projected to be 0.941 maf. The CY 2026 diversion for the Central Arizona Project (CAP) is projected to be 0.924 maf. Consumptive use for Nevada above Hoover (SNWP Use) is projected to be 0.188 maf for CY 2026.
Due to changing Lake Mead elevations, Hoover’s generator capacity is adjusted based on estimated effective capacity and plant availability. The estimated effective capacity is based on projected Lake Mead elevations. Unit capacity tests will be performed as the lake elevation changes. This study reflects these changes in the projections.
For questions on Upper Colorado River Basin (UCB) reservoir operations, please contact Alex Pivarnik, the UCB River Operations Group Supervisor, at apivarnik@usbr.gov. For questions on Lower Colorado River Basin (LCB) reservoir operations, please contact Noe Santos, the LCB River Operations Manager, at nsantos@usbr.gov.
Hoover, Davis, and Parker Dam historical gross energy figures come from Power, Operations, and Maintenance reports provided by the Lower Colorado Region’s Power Office, Bureau of Reclamation, Boulder City, Nevada. Questions regarding these historical energy numbers can be directed to Rebecca Rogers (rrogers@usbr.gov) or Kyra Cubi (kcubi@usbr.gov).
1 For modeling purposes, simulated years beyond 2026 assume a continuation of the 2007 Interim Guidelines including the 2024 Supplement to the 2007 Interim Guidelines (no additional SEIS conservation is assumed to occur after 2026), the 2019 Colorado River Basin Drought Contingency Plans, and Minute 323 including the Binational Water Scarcity Contingency Plan. With the exception of certain provisions related to Intentionally Created Surplus recovery and Upper Basin demand management, operations under these agreements are in effect through 2026. Reclamation initiated the process to develop operations for post-2026 in June 2023, and the modeling assumptions described here are subject to change.
2 The 2024 Interim Guidelines SEIS ROD is available online at: https://www.usbr.gov/ColoradoRiverBasin/documents/NearTermColoradoRiverOperations/20240507-Near-termColoradoRiverOperations-SEIS-RecordofDecision-signed_508.pdf.
3 For more information please visit: https://www.usbr.gov/newsroom/news-release/5326.
4 For more information please visit: https://www.usbr.gov/ColoradoRiverBasin/dcp/droa.
The 2026 Annual Operating Plan is available online at: https://www.usbr.gov/lc/region/g4000/aop/AOP26.pdf.
The Interim Guidelines are available online at: https://www.usbr.gov/lc/region/programs/strategies/RecordofDecision.pdf.
The Colorado River Drought Contingency Plans are available online at: https://www.usbr.gov/ColoradoRiverBasin/dcp/finaldocs.html.
The Upper Basin Hydrology Summary is available online at: https://www.usbr.gov/uc/water/crsp/studies/24Month_06_ucb.pdf.
Information on the LCB Conservation Program is available online at: https://www.usbr.gov/lc/LCBConservation.html.
Information on the 2024 Interim Guidelines SEIS ROD is available online at: https://www.usbr.gov/ColoradoRiverBasin/interimguidelines/seis/index.html.
Information on reservoir inflow observations and forecasts is available online at: https://www.cbrfc.noaa.gov/product/hydrofcst/hydrofcst.php.