Reclamation publishes “June 2023 Most Probable 24-Month Study”

Lake Powell
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July 17, 2023 — Lake Powell and Lake Mead, two of the Colorado River’s primary reservoirs, are crucial in water provision and electricity generation. The operations of these lakes rely on specific plans and guidelines. 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) regulate their operation. The 2023 Annual Operating Plan (AOP) provides an additional framework.  The Bureau of ReclamationOpens in a new tab. has released its June 2023 Most Probable 24-Month StudyOpens in a new tab. that considers these guidelines.

Key Aspects in Determining Operational Strategy.

The coordinated operation of Lake Powell and Lake Mead for 2023 is dictated by system storage and reservoir water surface elevations as per the August 2022 24-Month Study. If Lake Powell’s elevation is projected to be below 3,525 feet by January 1, 2023, it will be under the Lower Elevation Balancing Tier.

Controlling Water Release at Lake Powell.

The hydrologic conditions in April 2023 have projected an inflow of 11.30 million acre-feet (maf) into Lake Powell during the April-July runoff period. With this, the release volume from Lake Powell in the Water Year (WY) 2023 will likely range between 7.00 and 9.50 maf following the Interim Guidelines. The goal is to maintain Lake Powell’s elevation above 3,525 feet by the end of December 2023.

Factors Impacting Lake Mead Projections.

Projections for Lake Mead are influenced by several factors, such as updated water orders, conservation efforts, system conservation agreements, and inflow projections from the Lower Basin tributaries. These considerations aid in effectively managing the operations of Lake Mead.

Release Balance and Continuous Modelling.

The June 2023 24-Month Study projects a balancing release of 9.16 maf from Lake Powell in WY 2023. However, this release may change depending on the hydrology and reservoir conditions, potentially ranging between 7.00 and 9.50 maf. Monthly updates will be provided for these release projections.

Drought Response Operations Agreement: Suspension and Recovery.

The Drought Response Operations Agreement (DROA) Plan for 2022 was modified to halt releases as of March 7, 2023. The goal for 2023 is to maximize DROA recovery in the Upper Initial Units until April 2024.

New DROA Plan for 2023 and its Impact on Lake Mead.

Parties involved in the DROA have consented to the 2023 DROA Plan, focusing on recovery of prior DROA releases from units upstream of Lake Powell. This plan does not encompass any new DROA releases.

Proactive Monitoring and Additional Measures.

To maintain the health of the reservoirs, the Reclamation will continue assessing hydrologic and operational conditions. They will consult with Basin States, Basin Tribes, Mexico, and other partners to determine if further measures are required.

Operating Lake Mead in 2023.

In 2023, the operation of Lake Mead will be in accordance with a Shortage Condition under the Interim Guidelines, as per the August 2022 24-Month Study. The Lower Basin Drought Contingency Plan (DCP) Agreement and the 2021 Lower Basin Memorandum of Understanding (MOU) will be crucial in conserving Lake Mead’s water.

Runoff Projections and Diversion Estimates.

The National Weather Service’s Colorado Basin River Forecast Center provides runoff projections for Lake Powell. They also provide projected diversions for the Metropolitan Water District of Southern California (MWD), Central Arizona Project (CAP), and Nevada (SNWP Use).

Lake Mead Elevation and Hoover Dam Adjustments.

As Lake Mead’s water levels fluctuate, changes are made to Hoover Dam’s generator capacity. The estimated effective capacity depends on projected elevations, and unit capacity tests are conducted accordingly.

Lake Powell and Lake Mead operations follow the Interim Guidelines and the Annual Operating Plan. Inflows, storage, and operational conditions inform projections, releases, and reservoir management. Stakeholder coordination and continuous monitoring ensure the preservation of these crucial water resources.


Since 1995, Deborah has owned and operated LegalTech LLC with a focus on water rights. Before moving to Arizona in 1986, she worked as a quality control analyst for Honeywell and in commercial real estate, both in Texas. She learned about Arizona's water rights from the late and great attorney Michael Brophy of Ryley, Carlock & Applewhite. Her side interests are writing (and reading), Wordpress programming and much more.

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