Glen Canyon Dam

Glen Canyon Dam

Current Status

Last Updated: August 21, 2026

The unregulated inflow volume to Lake Powell during July was 84 thousand acre-feet (kaf) (9 percent of average). The release volume from Glen Canyon Dam in July was 482 kaf. The end of July elevation and storage of Lake Powell were 3,522.41 feet (approx. 178 feet from full pool) and 5.39 million acre-feet (maf) (23 percent of live capacity), respectively.

To view the most current reservoir elevation projections, click on: Lake Powell Elevation Projections.
To view the most current monthly release projections, click on: Lake Powell Release Projections.
To view the 2026 progession of snowpack above Lake Powell, click on Lake Powell Snow Chart.
To view the current inflow forecast relative to past inflows, click on Lake Powell Inflow Forecast.

Current Operations

The August 2025 24-Month Study projected the January 1, 2026, Lake Powell elevation to be less than 3,575 feet and at or above 3,525 feet and the Lake Mead elevation to be at or above 1,025 feet. Consistent with Section 6.C.1 of the Interim Guidelines, and Section 6.E of the 2024 Interim Guidelines SEIS ROD, the operational tier for Lake Powell in WY 2026 is the Mid-Elevation Release Tier and the water year release volume from Lake Powell was projected to be 7.48 maf. Given the hydrologic variability of the Colorado River System, the actual water year 2026 operations, and being consistent with Section 6.E of the 2024 Interim Guidelines SEIS ROD, the projected release from Lake Powell in water year 2026 may be less than 7.48 maf. The annual release volume from Lake Powell during water year 2026 is 6.0 maf under the Mid-Elevation Release Tier as determined under Section 6.C.1 of the Interim Guidelines and Section 6.E of the 2024 Interim Guidelines SEIS ROD as determined by the Department of the Interior.

On May 9, 2024, Reclamation published the 2024 Interim Guidelines SEIS ROD, which included modifications to Sections 2, 6, and 7 of the 2007 Interim Guidelines. The current 24-Month Study reflects these modifications in modeled operations.

On July 3, 2024, Reclamation signed the Glen Canyon Dam Long-Term Experimental and Management Plan Supplemental Environmental Impact Statement Record of Decision (2024 LTEMP SEIS ROD). The 2024 LTEMP SEIS ROD analyzed flow options to disrupt smallmouth bass and other warm water invasive non-native fish from establishing below Glen Canyon Dam by interrupting spawning and species expansion. Reclamation initiated these flows on August 3, 2025 and returned to normal operations on October 21, 2025.

The anticipated monthly release volume for August 2026 is 482,000 acre-feet. The September volume and the hourly pattern will be confirmed with a subsequent directive toward the end of August.

The August 2026 24-Month Study projected the October 1, 2026 Lake Powell elevation to be less than 3,540 feet and Lake Powell’s elevation is projected to decline below 3,510 feet during water year (WY) 2027. Consistent with Section 5.1.C.2 of the 2027-2028 Operating Guidelines, operations for Lake Powell in WY 2027 will be guided by the Low Elevation Infrastructure Protection Range and the expected WY 2027 release will be in the range between 6.00 million acre-feet (maf) to 7.00 maf. The WY 2027 release may be outside of the identified range, subject to appropriate consultation, in accordance with Section 5.1.C.2 of the 2027-2028 Operating Guidelines.

Releases from Glen Canyon Dam can also fluctuate beyond scheduled releases when called upon to respond to unscheduled power outages or power system emergencies. Depending on the severity of the system emergency, the response from Glen Canyon Dam can be significant, within the full range of the operating capacity of the power plant for as long as is necessary to maintain balance in the transmission system. Glen Canyon Dam currently maintains 30 MW (approximately 1,000 cfs) of generation capacity, in reserve in order to respond to a system emergency even when generation rates are already high. System emergencies occur infrequently and typically require small responses from Glen Canyon Dam. However, these responses can have a noticeable impact on the river downstream of Glen Canyon Dam.

Inflow Forecasts and Model Projections

The forecast for water year 2026 unregulated inflow to Lake Powell, issued on August 1, 2026, by the Colorado Basin River Forecast Center, projects that the most probable (median) unregulated inflow volume in water year 2026 will be 3.59 maf (37 percent of average).

In addition to the August 2026 24-Month Study based on the Most Probable inflow scenario, Reclamation has conducted runs to determine a possible range of reservoir elevations. The 24-Month Study minimum, most, and maximum probable scenarios were used to determine the range of probable outcomes. The probable minimum and probable maximum model runs are conducted simultaneously in January, April, August, and October, or when necessary to incorporate changing conditions. The probable minimum inflow scenario reflects a dry hydrologic condition which statistically would be exceeded 90 percent of the time. The most probable inflow scenario reflects a median hydrologic condition which statistically would be exceeded 50 percent of the time. The probable maximum inflow scenario reflects a wet hydrologic condition which statistically would be exceeded 10 percent of the time. There is approximately an 80 percent probability that a future elevation will fall inside the range of the minimum and maximum inflow scenarios. Additionally, there are possible inflow scenarios that would result in reservoir elevations falling outside the ranges indicated in these reports.

The August forecast for water year 2027 ranges from a minimum probable of 3.60 maf (37 percent of average) to a maximum probable of 14.30 maf (149 percent of average) with the most probable forecast for water year 2027 of 7.30 maf (76 percent of average). There is a 10 percent chance that inflows could be higher than the current maximum probable forecast and a 10 percent chance that inflows could be lower than the minimum probable forecast.

Based on the current forecast of unregulated inflow for water year 2026, the August 24-Month Study projects Lake Powell elevation will end water year 2026 near 3,515.89 feet with approximately 5.03 maf in storage (22 percent of capacity). Projections of end of water year 2026 elevation using the August minimum and maximum inflow forecast results from the 24-Month Study model run are 3,515.89 feet and 3,515.89 feet, respectively.

Upper Colorado River Basin Hydrology

Upper Colorado River Basin regularly experiences significant year to year hydrologic variability. The 30-year average was updated in October 2022 from 1981 through 2010 to 1991 through 2020. Shifting the period of record decreased the average unregulated inflow by 1.20 maf. The period 2000-2022 is the lowest 23-year period since the initial filling of Glen Canyon Dam in 1963, with an average unregulated inflow of 8.29 maf, or 93 percent of the 30-year average (1991-2020). (For comparison, the 1991-2020 total water year average is 9.60 maf.) The unregulated inflow during the 2000-2025 period ranged from a low of 2.64 maf (28 percent of average) in water year 2002 to a high of 15.97 maf (166 percent of average) in water year 2011. In water year 2021 unregulated inflow volume to Lake Powell was 3.50 maf (36 percent of average), the second driest year on record above 2002.

At the beginning of water year 2026, total system storage in the Colorado River Basin was 21.8 maf (37 percent of 58.48 maf total system capacity). This is a decrease of 3.35 maf over the total storage at the beginning of water year 2025 when total system storage was 25.15 maf (43 percent of capacity). Since the beginning of water year 2000, total Colorado Basin storage has experienced year to year increases and decreases in response to wet and dry hydrology, ranging from a high of 94 percent of capacity at the beginning of 2000 to the beginning of water year 2023 with 19.55 maf (33 percent of capacity).


Contact

Please contact the Operations Group via e-mail at ResourceMgr@usbr.gov for additional information.

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Last Updated: 8/21/26