Colorado River Basin

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Projected Operations

Reclamation's Upper and Lower Colorado Basin Regions generate a set of standard projections of Colorado River Basin system conditions at regular intervals to determine reservoir operations and assist with planning. These projections focus on annual to mid-term projections, with monthly updates to two-year projections, and updates to projections beyond two years occurring several times throughout the year.

More information about Reclamation's current projections can be found below.

Annual Operating Plans for Colorado River Reservoirs

Each year's Annual Operating Plan for Colorado River Reservoirs reports on both the past operations of the Colorado River reservoirs for the completed year as well as projected operations and releases from these reservoirs for the current (i.e., upcoming) year.

Annual Operating Plans are developed in accordance with Section 602 of the Colorado River Basin Project Act Link is to a PDF file (Public Law 90-537); the Criteria for Coordinated Long-Range Operation of Colorado River Reservoirs Pursuant to the Colorado River Basin Project Act of September 30, 1968, as amended Link is to a PDF file, promulgated by the Secretary of the Interior; and Section 1804(c)(3) of the Grand Canyon Protection Act (Public Law 102-575).

AOPs are prepared in consultation with representatives of the Governors of the seven Colorado River Basin States, Indian Tribes, Upper Colorado River Commission, appropriate Federal agencies, and others interested in Colorado River operations.

Federally recognized tribes in the Colorado River Basin
Publication Date Report Title
05/2022 Draft Annual Operating Plan for Colorado River Reservoirs 2023 – First Consultation Link is to a PDF file
12/2021 Annual Operating Plan for Colorado River Reservoirs 2022 Link is to a PDF file
12/2020 Annual Operating Plan for Colorado River Reservoirs 2021 Link is to a PDF file
12/2019 Annual Operating Plan for Colorado River Reservoirs 2020 Link is to a PDF file
07/2019 Annual Operating Plan for Colorado River Reservoirs 2019 Link is to a PDF file
12/2017 Annual Operating Plan for Colorado River Reservoirs 2018 Link is to a PDF file
12/2016 Annual Operating Plan for Colorado River Reservoirs 2017 Link is to a PDF file
01/2016 Annual Operating Plan for Colorado River Reservoirs 2016 Link is to a PDF file
12/2014 Annual Operating Plan for Colorado River Reservoirs 2015 Link is to a PDF file
12/2013 Annual Operating Plan for Colorado River Reservoirs 2014 Link is to a PDF file
01/2013 Annual Operating Plan for Colorado River Reservoirs 2013 Link is to a PDF file
12/2011 Annual Operating Plan for Colorado River Reservoirs 2012 Link is to a PDF file
01/2011 Annual Operating Plan for Colorado River Reservoirs 2011 Link is to a PDF file
01/2010 Annual Operating Plan for Colorado River Reservoirs 2010 Link is to a PDF file
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Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations for Lake Powell and Lake Mead

In 2005, Pursuant to the National Environmental Policy Act, Reclamation began public scoping meetings and preparing an EIS for the development of Lower Colorado River Basin Shortage Guidelines and Coordinated Management Strategies for Operation of Lake Powell and Lake Mead Under Low Reservoir Conditions. The Secretary of the Interior has directed Reclamation to develop additional Colorado River management strategies to address operations of Lake Powell and Lake Mead under low reservoir conditions by 2007.

Panoramic view of Hoover Dam and Lake Mead
Hoover Dam and Lake Mead

These operational guidelines provided Colorado River water users and managers in the United States a greater degree of certainty about how the two large reservoirs on the Colorado River will be operated under low water conditions, and when – and by how much – water deliveries will be reduced to the Lower Basin states of Arizona, California, and Nevada in the event of drought or other low reservoir conditions. In a separate, cooperative process, Reclamation worked through the State Department to consult with Mexico regarding potential water delivery reductions to Mexico under the 1944 Treaty with the United States.

A ROD was signed by the Secretary in December 2007 that implements the interim operational guidelines that will be in place through 2026. The key components of the guidelines are:

  1. a shortage strategy for Lake Mead and the Lower Division states,
  2. coordinated operations of Lakes Powell and Mead through a full range of operations,
  3. a mechanism for the creation and delivery of conserved system and non-system water in Lake Mead (Intentionally Created Surplus), and
  4. the modification and extension of the existing Interim Surplus Guidelines.

Consistent with Section XI.G.7.D. of the 2007 Interim Guidelines Record of Decision, Reclamation completed a review of the implementation of the Guidelines (7.D. Review). The review is a retrospective look at past operations and actions under the 2007 Interim Guidelines and is not a consideration of future activities. Through this 7.D. Review, Reclamation built a solid technical foundation that informs future consideration of operations and brings partners, stakeholders, and the public to common understanding of past operations and their effectiveness. The 7.D. Review was completed in December 2020.

Reclamation anticipates formally starting the National Environmental Policy Act process to develop the post-2026 operations with the beginning of the formal scoping process in early 2023. As the focus shifts to the declining storage, increasing risk of water shortages in the Colorado River Basin and short-term response actions, Reclamation recognizes the importance of simultaneously planning for the longer-term. The goal is to develop a robust public involvement approach that will appropriately include meaningful and timely engagement with the Basin States, tribes, partners, and stakeholders to ensure their objectives and priorities are considered.

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Final Report of the Review of the 2007 Interim Guidelines (7.D. Review)

Reclamation released the Final Report of the 7.D. Review on December 18, 2020.

Through the 7.D. Review, Reclamation intended to bring partners, stakeholders, and the public to a common understanding of past operations under the 2007 Interim Guidelines and their effectiveness. The goals of the Review were to: evaluate the effectiveness of the Guidelines and document Reclamation's operational experience since the Guidelines were adopted. The 7.D. Review Report will be one of many references and sources of input considered when work begins to determine Lake Powell and Mead operations after 2026.

Draft report cover

The Final Report concluded:

  • The 2007 Interim Guidelines were largely effective as measured against both their stated purpose and common themes as provided in the 2007 Record of Decision.
  • Increasing severity of the drought necessitated additional action to reduce the risk of reaching critically low elevations in Lakes Powell and Mead.
  • Experience over the past 12 years provides important considerations:
    • enhanced flexibilities and transparency for water users
    • expanded participation in conservation and Basin-wide programs
    • increased consideration of the linkage that occurs through coordinated reservoir operations, particularly with respect to the inherent uncertainties in model projections used to set operating conditions
    • demonstrated need for more robust measures to protect reservoir levels

The Final Report is available here:

Click here for more info on the development of the 7.D. Review & Report

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Operating under the 2007 Interim Guidelines

The 2007 Interim Guidelines are in place from 2008 through December 31, 2025 (through preparation of the 2026 Annual Operating Plan).  Reclamation’s Upper and Lower Colorado Basin Regions manage the operations of Lake Powell and Lake Mead pursuant to the Record of Decision for the 2007 Interim Guidelines Link is to a PDF file. The coordinated operational diagram below outlines the coordinated reservoir operations of both reservoirs at different pool elevations. Several implementing agreements were executed concurrent to the issuance of the 2007 ROD, related to forbearance and the creation and delivery of ICS by Lower Basin contractors, as well as subsequent agreements for System Efficiency ICS projects.

Lake Powell and Lake Mead Operational Diagrams from the 2007 Interim Guidelines. Above an elevation of 3,636 feet in 2008 to 3,666 feet in 2026 Powell operates in the Equalization Tier to equalize, avoid spills, or release 8.23 million acre-feet. Below this elevation but at or above elevation 3,575 feet, Powell operates in the Upper Elevation Balancing Tier, subject to April adjustments which may result in a release according to the Equalization Tier. In the Upper Elevation Balancing Tier Powell releases 8.23 million acre-feet; if Lake Mead is below 1,075 feet, balance contents with a min/max release of 7.0 and 9.0 million acre-feet. Below elevation 3,575 feet and at or above 3,525 feet Powell operates in the Mid-Elevation Release Tier releasing 7.48 million acre-feet. If Lake Mead is below 1,025 feet, then Powell releases 8.23 million acre-feet. Below elevation 3,525 feet Powell operates in the Lower Elevation Balancing Tier balancing contents with a min/max release of 7.0 and 9.5 million acre-feet. Above an approximate elevation of 1,200 feet Lake Mead is in Flood Control Surplus or Quantified Surplus Conditions delivering more than 7.5 million acre-feet. This elevation is approximate as it is determined each year by considering several factors including Lake Powell and Lake Mead storage, projected Upper Basin and Lower Basin demands, and an assumed inflow. Below the elevation of approximately 1,200 feet to at or above 1,145 feet Lake Mead is in the Domestic Surplus or ICS Surplus Condition delivering more than 7.5 million acre-feet. Below 1,145 feet and above 1,075 feet Lake Mead is in the Normal or ICS Surplus Condition delivering greater than or equal to 7.5 million acre-feet. At or below 1,075 feet and at or above 1,050 feet Lake Mead is in a Shortage Condition delivering 7.167 million acre-feet, of which 2.48 million acre-feet is apportioned to Arizona, 4.4 million acre-feet to California, and 0.287 million acre-feet to Nevada. Below 1,050 feet and at or above 1,025 feet Lake Mead is in a Shortage Condition delivering 7.083 million acre feet, of which 2.40 million acre-feet is apportioned to Arizona, 4.4 million acre-feet to California, and 0.283 million acre-feet to Nevada. Below 1,025 feet Lake Mead is in a Shortage Condition delivering 7.0 million acre-feet, of which 2.32 million acre-feet is apportioned to Arizona, 4.4 million acre-feet to California, and 0.280 million acre-feet to Nevada. Further measures may be undertaken as whenever Lake Mead is below elevation 1,025 feet, the Secretary of Interior shall consider whether hydrologic conditions together with anticipated deliveries to the Lower Division States and Mexico is likely to cause the elevation at Lake Mead to fall below 1,000 feet. Such consideration, in consultation with the Basin States, may result in the undertaking of further measures, consistent with Federal law.
Lake Powell and Lake Mead Operational Diagrams from the 2007 Interim Guidelines. Click on diagram to view full size.

Development of the 2007 Interim Guidelines

Spurred by the ongoing multi-year drought, decreasing system storage, and growing demands for Colorado River water, in May 2005, the Secretary directed Reclamation to develop additional strategies for improving coordinated management of the reservoirs of the Colorado River system.

Each year, the Secretary is required to declare the Colorado River water supply availability conditions for the Lower Division states (Arizona, California, and Nevada) in terms of Normal, Surplus, or Shortage. In 2005, regulations and operations criteria had been developed for Normal and Surplus conditions, but detailed guidelines for a water supply shortage had not been established. It was anticipated that, among other elements, these additional strategies would identify those circumstances under which the Secretary would reduce annual water deliveries from Lake Mead such that use of mainstream water by the Lower Division states is below the 7.5 million acre-feet apportionment (a "Shortage") pursuant to Article II of the Decree in Arizona v. California.

In response to the Secretary's direction, Reclamation initiated a National Environmental Policy Act process and preparation of an Environmental Impact Statement to develop and adopt interim operational guidelines to address the operations of Lake Powell and Lake Mead during drought and low reservoir conditions. The proposed Federal Action included four key elements:

  • Shortage strategy for Lake Mead and the Lower Division states
  • Coordinated operation of Lakes Powell and Mead
  • Mechanism for the storage and delivery of system and non-system water in Lake Mead
  • Proposed modification/extension of the existing Interim Surplus Guidelines

Five federal agencies participated in the EIS process as Cooperating Agencies: the Bureau of Indian Affairs, the National Park Service, the U.S. Fish and Wildlife Service, the Western Area Power Administration, and the U.S. Section of the International Boundary and Water Commission. The Cooperating Agencies met regularly with Reclamation, assisted with the development and evaluation of alternatives, and assisted in the preparation of the EIS. Reclamation also coordinated the development of the EIS with the seven Basin States, Indian Tribal Governments, Mexico, other key stakeholders and interested parties, and the public. Meetings with these various groups occurred throughout the process in addition to the multiple public scoping meetings held throughout the Basin.

A Draft EIS was released at the end of February 2007 and a Final EIS was published in November 2007. The outcome of the NEPA process was the 2007 Interim Guidelines. On Dec 13, 2007 the Secretary of the Interior signed the historic decision that implements innovative strategies for Colorado River management, charting a water management course for the future.

Project Documents

Documents related to the development of the 2007 Interim Guidelines are available below.

ROD & EIS DOCUMENTS
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Contact Us

Upper Colorado Basin Region

Please contact the Upper Colorado Basin Region Public Affairs Office via e-mail at ucbpao@usbr.gov for additional questions or information.

Lower Colorado Basin Region

Please contact the Water Operations Control Center via e-mail at bcoowaterops@usbr.gov or via phone at (702) 293-8373 for additional questions or information.

Last Updated: 5/22/23