New federal framework charts the Colorado River’s next decade

The Colorado River supplies roughly 40 million people, 5.5 million acres of irrigated land, and extensive tribal, environmental, and hydropower interests across seven US states and Mexico.

Prolonged drought and accelerating aridification have prompted ongoing legal, policy, and operational discussions for how to manage the Colorado River’s water after key shortage and drought contingency agreements expire at the end of 2026. The discussions have occurred among the seven Basin states (Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming), 30 federally recognized Basin Tribes, and the federal government. After years of negotiations, the Upper Basin states (Colorado, New Mexico, Utah, and Wyoming) and Lower Basin states (Arizona, California, and Nevada) were unable to reach agreement on a post-2026 framework to govern the Colorado River amid deepening shortages.

On July 31, 2026, the US Department of the Interior’s Bureau of Reclamation released the Post 2026 Colorado River Reservoir Operations Final Environmental Impact Statement (Final EIS). The Final EIS establishes operation guidelines at Lake Powell, Lake Mead, and key infrastructure following expiration of the agreements. For the first two years, 2027–2028, the Final EIS adopts the reductions that the Lower Basin states had proposed for themselves in the context of negotiations with the Upper Basin states. After 2028, the framework takes an adaptive approach, revising operating guidelines at subsequent two-year intervals through 2036. The Final EIS does not impose mandatory reductions on the Upper Basin states.

This alert explores how the Final EIS may affect municipalities, agricultural districts, utilities, developers, Tribes, and other organizations that depend on Colorado River water during the 2027–2036 operating period.

Key details

The agreements that have governed Colorado River Basin water deliveries for nearly two decades – the 2007 Interim Guidelines, the 2019 Drought Contingency Plans, and related international agreements – expire at the end of 2026. These guidelines introduced significant measures to address drought conditions and declining reservoir levels. Nevertheless, Lake Powell and Lake Mead have continued to experience historically low elevations during a prolonged drought that began in 2000.

The Secretary of the Interior, acting through the Bureau of Reclamation, is responsible for coordinating long range reservoir operations. In addition to Glen Canyon Dam and Hoover Dam, the Final EIS states that the federal action “may include actions upstream and downstream of these facilities to protect critical reservoir elevations, such as use of the Colorado River Storage Project (CRSP) Upper Initial Units to release additional water if needed to protect critical infrastructure at Glen Canyon Dam, and approaches to enhance opportunities for Lower Basin water users to reduce water use.” As existing operating agreements approach expiration, the Final EIS establishes a framework for post-2026 Colorado River operations beginning January 1, 2027, as long-term water demand continues to exceed available supply.

The Final EIS is the product of a four-year National Environmental Policy Act (NEPA) process that evaluates several alternatives and selects a “Preferred Alternative” – the framework the federal government intends to implement. The Bureau of Reclamation concluded that climate driven aridification and persistently low runoff conditions will continue to exacerbate the imbalance between water supply and demand. Accordingly, the Preferred Alternative sets an adaptive decision framework rather than another fixed ten year rule set.

What the framework does and does not do

Recognizing uncertainty in future hydrologic conditions, the Bureau of Reclamation applies a Decision Making under Deep Uncertainty methodology, modeling 400 potential hydrologic futures and evaluating alternatives across a wide range of possible conditions.

Using that methodology, the Final EIS evaluates a No Action Alternative and five action alternatives as required under NEPA. The analysis focuses on tradeoffs among the following:

• Maintaining Lake Powell and Lake Mead water levels above critical elevations
  
  
• Preventing reservoirs from reaching “dead pool” conditions, where water can no longer be released
  
  
• The size and frequency of delivery shortages to Lower Basin states
  
  
• Average annual water releases from Glen Canyon Dam, which determine how much water the Lower Basin states receive
  
  
• Hydropower generation, salinity control, water quality, environmental protection, ecological and recreation outcomes, and socioeconomic impacts

The Bureau of Reclamation’s Preferred Alternative: A ten-year adaptive decision framework

The Bureau of Reclamation selected a Preferred Alternative that establishes an adaptive decision framework rather than a fixed set of operating rules for the 2027–2036 period. Under this approach, the federal government will adopt operating guidelines at anticipated two year intervals, although longer intervals could follow consensus based agreements. For each interval, the Department of the Interior will issue a decision document published in the Federal Register, which will set specific operating guidelines, which will be implemented through Annual Operating Plans. The framework itself is intended to remain constant through 2036, unless modified by future federal action and environmental review.

Four operational principles shape each decision within the framework:

1. Responsiveness to hydrology. Annual operations and mid-year adjustments must account for evolving supply conditions to support adaptive management.

2. Protection of critical federal infrastructure. When Lake Powell is projected below 3,500 feet in elevation or Lake Mead below 1,000 feet, the framework will trigger processes and tools to manage infrastructure risks at the respective Glen Canyon Dam and Hoover Dam.

3. Implementation of Long-Range Operating Criteria (LROC) with allowance for extraordinary actions. Operating guidelines must provide objective criteria for low reservoir operations within LROC bounds, while allowing for temporary additional actions when needed to protect critical infrastructure, consistent with federal law.

4. Priority for consensus-based recommendations. The Final EIS indicates that Department of the Interior will prioritize adoption of consensus agreements that provide multi-party benefits and adequate system protection. In the absence of consensus, the Secretary will act unilaterally as necessary within applicable law.

The numbers

Because the Preferred Alternative establishes an adaptive framework that depends on actual operating conditions, the Final EIS uses a Representative Preferred Alternative, which is a set of modeling assumptions to analyze environmental effects and compare performance across alternatives. Under this modeling, the key projected figures include the following:

• Annual water releases from Lake Powell could vary from 5.0 to 12.0 million acre-feet (MAF) based on elevation and equalization triggers. The historic norm was closer to 8.23 MAF.
  
  
• Combined Lower Basin shortages could reach 3.6 MAF per year – roughly 40 percent of those states’ Colorado River allocation under the original 1922 Compact. For 2027- 2028, the first 1.5 MAF of cuts would follow a formula the Lower Basin states proposed. After 2028, absent a new agreement, cuts will shift to a strict priority-based distribution, where the most junior water rights are reduced first.
  
  
• The Representative Preferred Alternative avoids complete delivery failure, or dead pool in 95 percent of modeled futures through 2039, achieving the strongest performance among the alternatives evaluated.

Implications for stakeholders

Three key observations emerge from the Final EIS regarding Colorado River operations:

1. Protection of critical infrastructure is a central objective under the framework. Each alternative in the Final EIS prioritizes operations at Hoover Dam and Glen Canyon Dam, which provide electricity to millions in the Southwest. Maintaining the Bureau of Reclamation’s facilities under all runoff conditions is a central objective of the framework.

2. The Final EIS imposes reductions on the Lower Basin states while the Upper Basin states face no mandatory cuts – raising significant legal questions. Despite years of negotiation, the Basin states have not reached consensus on post-2026 operating guidelines. Under the framework, the federal government has set reductions on the Lower Basin states with no mandatory cuts imposed on the Upper Basin states. The federal government’s authority to mandate such reductions remains a contested question under the 1922 Colorado River Compact and related federal law.

3. Arizona holds the most junior priority rights. For 2027 and 2028, the government’s reductions track the Lower Basin states proposal submitted in May 2026: Arizona would cut 760,000 acre-feet (AF), California 440,000 AF, and Nevada 50,000 AF, for a total of 1.25 MAF per year. Because Arizona holds the most junior priority rights to the Colorado River water among the Lower Basin states, it would bear the greatest share of any post-2028 reductions under a priority-based distribution if adopted by the government. However, further agreement among the Lower Basin states, or all the Basin states, could alter that outcome given the framework’s adaptive approach.

For more information

Our Water and Environmental, Health, and Safety teams are available to advise on developments affecting the Colorado River and its stakeholders. For more information, please contact the authors.