- The Colorado River serves about 40 million people and millions of acres of farmland.
- Long-term drought since 2000 has pushed reservoirs to dangerously low levels.
- Water use often exceeds the river’s natural supply.
- Federal officials are preparing major changes for operations after 2026.
Friday, April 3, 2026 — The Congressional Research Service
released an updated report for Congress examining how the Colorado River is managed, how drought is affecting supplies, and what role the federal government may play moving forward. The Congressional Research Service is a nonpartisan research arm of Congress, and its reports are widely used by lawmakers to understand complex policy issues.
The March 31, 2026, report outlines long-standing legal agreements, current water shortages, and the approaching expiration of key operating rules in 2026. It also signals that Congress may soon face important decisions about funding, authority, and long-term management of one of the West’s most critical water systems.
Key Laws Shaping the Colorado River.
The report reviews a series of laws and agreements that together form what is often called the “Law of the River.” These rules govern how water is shared and managed.
- Colorado River Compact of 1922. Divided the river between the Upper Basin and Lower Basin, allocating 7.5 million acre-feet to each.
- Boulder Canyon Project Act of 1928. Approved Hoover Dam and assigned Lower Basin water shares among California, Arizona, and Nevada.
- 1944 U.S.-Mexico Water Treaty. Requires the United States to deliver 1.5 million acre-feet of water annually to Mexico.
- Arizona v. California (1963). A Supreme Court decision that clarified water rights and confirmed federal authority over Lower Basin deliveries.
- Colorado River Basin Project Act of 1968. Authorized major infrastructure projects and coordinated reservoir operations.
- Inflation Reduction Act (P.L. 117-169). Provided funding to support water conservation efforts in the basin.
A River That Supports the West.
The Colorado River is one of the most important water sources in the United States. It stretches across more than 246,000 square miles and serves seven states and parts of Mexico. It provides water for cities, farms, industries, wildlife, and recreation.
Roughly 70 percent of the river’s water is used to irrigate about 5.5 million acres of farmland. It also supplies drinking water to nearly 40 million people, including major cities far outside the river basin through large pipelines and canals.
The river is also tied to electricity production. Hydropower dams along the river can generate thousands of megawatts of power, while also supporting fish, wildlife, and recreation areas across the West.
How the River Is Divided.
The Colorado River is governed by a complex set of agreements often called the “Law of the River.” These include compacts, treaties, court decisions, and federal laws.
At the center is the Colorado River Compact of 1922. It divided the river into two regions:
- The Upper Basin, including Colorado, Wyoming, Utah, and New Mexico.
- The Lower Basin, including Arizona, Nevada, and California.
Each basin was originally allocated 7.5 million acre-feet of water per year. Later, a 1944 treaty required the United States to deliver 1.5 million acre-feet annually to Mexico.
, using data from U.S. Geological Survey; Esri Data & Maps, 2017; Central Arizona Project; and Esri World Shaded Relief Map.A Growing Imbalance.
The biggest challenge facing the Colorado River is simple but serious: more water is being used than the river produces.
Natural river flows averaged about 14.6 million acre-feet per year during the 20th century. Since 2000, that average has dropped to about 12.4 million acre-feet.
At the same time, demand has stayed high. In many years, water use plus losses such as evaporation exceed the river’s total supply.
Two Decades of Drought.
Dry conditions began in the early 2000s and have continued for more than two decades. According to federal data, the period from 2000 to 2022 was the driest 23-year stretch in more than a century of recordkeeping and possibly one of the driest in over 1,000 years.
Federal Proposals and State Disagreements.
As existing agreements near expiration in 2026, federal officials have outlined several possible paths forward, but the states have not agreed on a single approach.
In January 2026, the Bureau of Reclamation released a draft environmental review describing four possible alternatives for managing the river after 2026.
While details vary, the main approaches include:
- Shared shortage approach. Reduces water deliveries across both Upper and Lower Basin states based on reservoir levels.
- Lower Basin-focused cuts. Places a larger share of reductions on Arizona, Nevada, and California, where most water is used.
- Reservoir protection strategies. Prioritizes keeping Lake Powell and Lake Mead above critical levels to protect water deliveries and hydropower.
- Operational flexibility options. Adjusts how water is stored, released, and credited to users across the system.
According to the report, state leaders remain divided, particularly between Upper Basin and Lower Basin states, over how shortages should be shared.
Some of the proposed options may require new authority from Congress before they can be fully implemented.
If no agreement is reached, federal officials have indicated they may proceed under existing authority.
Efforts to Save Water.
Over the years, states and the federal government have worked together on several agreements to reduce water use and stretch supplies.
Key agreements were reached in 2003, 2007, 2019, and 2023. These plans focused on:
- Cutting water use.
- Adding flexibility in how water is stored and released.
- Sharing shortages among states.
The most recent agreement required the Lower Basin states to conserve about 3 million acre-feet of water between 2023 and 2026. Much of that effort is supported by federal funding.
A Critical Deadline in 2026.
Many of the current water-saving agreements expire at the end of 2026.
A final federal decision on long-term operations is expected before October 1, 2026.
The Federal Government’s Role.
Congress plays a central role in managing the Colorado River system.
It funds major dams and water projects, approves laws affecting water use, and oversees federal agencies such as the Bureau of Reclamation.
What Comes Next.
The Colorado River is entering a period of major change.
Decades of drought, growing demand, and shrinking supplies have created a situation where difficult decisions can no longer be delayed.
Frequently Asked Questions.
What is the Colorado River used for?
The river supplies water for farms, cities, industry, hydropower, and wildlife across the western United States and parts of Mexico.
Why is the Colorado River in trouble?
Water demand often exceeds supply, and long-term drought has reduced the amount of water flowing into the system.
What happens in 2026?
Current agreements that govern water use expire, and new rules must be finalized for future operations.
Why can’t the states agree?
Upper Basin and Lower Basin states have different priorities and water use patterns, leading to disagreements over how to share shortages.
What role does Congress play?
Congress provides funding, approves laws, and may need to authorize new measures for managing the river.
Could the federal government act without the states?
Yes. If no agreement is reached, federal officials may act using existing legal authority, although some options could require congressional approval.
