Responding to Drought in the Colorado River Basin
Changes from May 7, 2026 to August 3, 2026
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The Colorado River Basin covers more than 246,000 square miles in seven U.S. states and Mexico. Basin waters are governed by multiple documents, known collectively as the Law of the River. The Colorado River Compact of 1922 established the framework to apportion water supplies between the river's Upper and Lower Basins, with each basin allocated 7.5 million acre-feet (MAF) annually; a subsequent agreement also provided for releases to Mexico (Figure 1). The Bureau of Reclamation (Reclamation) plays a prominent role in basin water management due to the many congressionally authorized projects in the basin.
When federal and state governments approved the Colorado River Compact of 1922, it wascompact, they assumed that river flows would average 16.4 MAF per /year. Actual annual flows from 1906 to 2024 were approximately 14.6 MAF and have averaged significantly less (12.4 MAF) since 2000from 2000 through 2024. Demand has exceeded these amounts in most years, and studies project lower flows in the future.
The imbalance between water supplies and demand has depleted storage in the basin's two largest reservoirs—Lake Powell in the Upper Basin and Lake Mead in the Lower Basinand Lake Mead—and threatens water supplies for millions in the Southwest. Storage at boththese reservoirs is near the lowest levels on recordat historically low levels. Reclamation makes operational decisions for basin reservoirs based on 24-month studies, which project conditions for upcoming yearsfuture conditions (Figure 2, Figure 3). Due to poor hydrology in 2026, storage in Lake Powell has the potential to reach critically low levels.
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Figure 2. Lake Powell Storage Elevations and Projections ( |
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Source: Bureau of Reclamation, "24-Month Study Projections." Notes: maf = million acre-feet; WY = water year |
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Figure 3. Lake Mead Storage Elevations and Projections ( |
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Source: Bureau of Reclamation, "24-Month Study Projections." Notes: maf = million acre-feet; WY = water year; DROA = Drought Response Operations Agreement. |
Mitigating Drought in the Colorado River Basin
Previous efforts to improve the basin's water supply outlook resulted in agreements in 2003, 2007, 2019, and 2024 that generally built on one another and reduced water deliveries. These agreementsagreements that tied Lower Basin delivery reductions to decreasing Lake Mead levels and implemented a framework to coordinatecoordinated Upper Basin operations so as to protect Lake Powell from reaching critically low levels.
Since 2020Pursuant to those agreements, Reclamation has curtailed water deliveries to Arizona and Nevada based on Lake Mead levels. It also made operational changes in the Upper Basin to move water, and some users have conserved water on a voluntary basis. Reclamation also moved Upper Basin waters from upstream reservoirs intoto Lake Powell in 2021 and, 2022, and it is implementing these operations again in 2026.
In 2026, Lower Basin states are expected to conserve a total of 1.3 MAF:will conserve an estimated 1.3 MAF, including roughly 533,000 AF in uncompensated reductions/savings under prior agreements and 770,000 AF under the 2024 plan (including federally in federally compensated water delivery reductions that were approved by Congress approved in P.L. 117-169, commonly referred to (popularly known as the Inflation Reduction Act [IRA]). Despite these reductions, experts agree that more cutbacks are still needed. Some, or IRA). However, some studies estimate that reductions of 2.4-3.2 MAF/year in reductions are needed to stabilize the system in the long term.
Post-2026 Operations
Most existing water conservation agreements expire at the end of 2026,; thus, Reclamation isundertook a process analyzing post-2026 operational alternatives for the system. In 2024, the Upper and Lower Basin states submitted competing "long-term" operational plans to Reclamation; each plan proposed different methods and allocations for Colorado River reductions.
Absent a consensus among Upper and Lower Basin states, in January 2026 Reclamation released a draft EIS with five alternatives (Table 1). Most alternatives would impose new Lower Basin delivery reductions in excess of recent levels and alter the basis and range of Lake Powell releases to the Lower Basin, among other things. The alternatives differ significantly in their operational triggers and the magnitude/distribution of reductions, and several of them would require congressional approval to be implemented. Reclamation has noted its preference for a consensus approach among basin states but reiterated its willingness to act unilaterally to make changes.
Table 1. Bureau of Reclamation Post-2026 Colorado River Operational Alternatives
(alternatives in January 2026 draft EIS)
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Alternative |
Range and Basis for Total Lower Basin Delivery Reductions |
Range and Basis for Lake Powell Releases |
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No Action |
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Basic Coordination |
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Enhanced Coordination |
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Maximum Operational Flexibility |
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Supply Driven |
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In early 2026, Reclamation published a draft EIS with five alternatives. In July 2026, Reclamation announced its preferred alternative in a Final EIS (FEIS), stipulating that going forward the basin would be operated in two-year intervals. This differed from the draft EIS plan to lay out long-term operations of 20 years.
Distribution of Annual Delivery Shortage Volumes for U.S. States and MexicoSource: Bureau of Reclamation, Post-2026 Operational Guidelines and Strategies for Lake Powell and Lake Mead, DraftThe Lower Basin proposed cuts in both basins and tying Lake Powell releases to system storage and Upper Basin consumption, among other things. The Upper Basin proposed additional Lower Basin cuts, no mandatory cuts for its users, and no major changes to the basis for Lake Powell releases.
, January 2026.
Notes: The preferred alternative also lays out numerous other operational elements, including allowing for annual releases from Glen Canyon Dam as low as 5.0 MAF/year if Lake Powell is projected to decline below 3,500 feet. The FEIS also provides for releases from other federal reservoirs in the Upper Basin to protect Glen Canyon Dam infrastructure, assumes voluntary conservation of 200,000 AF/year from the Upper Basin, and allows for additional conserved Lower Basin waters to be stored in Lake Mead, among other things. The two-year operating plan in the FEIS requires nonfederal approvals to implement but does not assume enactment of new federal authorities. This could change in future two-year plans. While states and some Members of Congress have called for federal funding to mitigate the effect of water delivery reductions on users (i.e., similar to previous IRA funding), no such funding has been enacted. MAF/year MAF = million acre-feet. Shortages are tied to Lake Mead elevation, as outlined in Reclamation's FEIS. The FEIS assumes Mexico cuts that have yet to be negotiated/announced.
= million acre-feet per year.
On May 1, 2026, the Lower Basin states announced a new 2026-2028 operations proposal. Under the proposal, they would collectively contribute reductions of 1.25 MAF/year and Mexico would contribute 250,000 AF/year (i.e., similar to amounts initially proposed under comparable conditions in the 2024 Lower Basin post-2026 proposal, but less than the draft EIS options) in 2027 and 2028. This would be coupled with a new 700,000 AF (total through 2028) Lower Basin conservation program that would be funded by a federal/state cost-share, resulting in total savings of 3.2 MAF through 2028. The proposal contains other operational assumptions and does not specify how much new federal funding would be needed to implement the conservation program. For its part, the Upper Basin has opposed efforts that do not reflect a basin-wide consensus and has reiterated its prior calls for mediation.