Glen Canyon Dam

Glen Canyon Dam

Current Status

Last Updated: July 15, 2024

The unregulated inflow volume to Lake Powell during June was 2,527 thousand acre-feet (kaf) (103 percent of average). The release volume from Glen Canyon Dam in June was 626 kaf. The end of June elevation and storage of Lake Powell were 3,585.60 feet (114 feet from full pool) and 9.75 million acre-feet (maf) (42 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 2024 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 operation of Lake Powell and Lake Mead in the June 2024 24-Month Study is pursuant to the December 2007 Record of Decision on Colorado River Interim Guidelines for Lower Basin Shortages and the Coordinated Operations of Lake Powell and Lake Mead (Interim Guidelines), the Supplemental Environmental Impact Statement for Near-term Colorado River Operations Record of Decision (2024 Interim Guidelines SEIS ROD), and reflects the draft 2024 Annual Operating Plan (AOP). Pursuant to the Interim Guidelines, the August 2023 24-Month study projects the January 1, 2024, 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 the operational tier for Lake Powell in water year 2024 is the Mid-Elevation Release Tier and the water year release volume from Lake Powell is 7.48 maf.

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.

The trigger to begin releasing cooler water from the river outlet works or bypass tubes at Glen Canyon Dam is three days of observed river temperatures above the threshold at River Mile 61 (Little Colorado River tributary). This temperature target has been met and Reclamation began releasing water from the river outlets on July 9, 2024, to cool water. Additional bypass releases will continue until the temperature threshold is no longer exceeded without additional outlet release. Reclamation is coordinating release patterns on a weekly basis in order to comply with the 2024 LTEMP SEIS ROD.

July release volume is 709,000 acre-feet and hourly releases will comply with the 2024 LTEMP SEIS ROD as described above. The pattern and volume for August will be confirmed at the end of July and is anticipated to vary from the current estimated pattern.

In addition to daily scheduled fluctuations for power generation, the instantaneous releases from Glen Canyon Dam may also fluctuate to provide 40 megawatts (MW) of system regulation. These instantaneous release adjustments stabilize the electrical generation and transmission system and translate to a range of about 1,300 cfs above or below the hourly scheduled release rate. Under normal system conditions, fluctuations for regulation are typically short lived and generally balance out over the hour with minimal or no noticeable impacts on downstream river flow conditions.

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 1,300 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 2024 unregulated inflow to Lake Powell, issued on July 1, 2024, by the Colorado Basin River Forecast Center, projects that the most probable (median) unregulated inflow volume in water year 2024 will be 8.13 maf (85 percent of average).

In addition to the July 2024 24-Month Study based on the Most Probable inflow scenario, Reclamation has conducted runs in June to determine a possible range of reservoir elevations. The July 2024 24-Month Study probable most and minimum and May 24-Month Study 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 July forecast for water year 2025 ranges from a minimum probable of 5.37 maf (56 percent of average) to a maximum probable of 16.90 maf (176 percent of average) with the most probable forecast for water year 2025 of 9.15 maf (95 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 for water year 2024 of 8.13 maf unregulated inflow volume, the July 24-Month Study projects Lake Powell elevation will end calendar year 2024 near 3576.45 feet with approximately 9.01 maf in storage (37 percent of capacity). Note that projections of elevation and storage for water year 2024 have significant uncertainty at this point in the season. Projections of end of water year 2024 elevation using the July minimum and May maximum inflow forecast results from the 24-Month Study 2024 model run are 3,572.05 feet and 3,583.86 feet, respectively. The annual release volume from Lake Powell during water year 2024 is 7.48 maf under the Mid-Elevation Release Tier as determined under Section 6.C.1 of the Interim Guidelines as determined by the Department of the Interior as described above.

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 1.20 maf. The period 2000-2022 is the lowest 23-year period since the closure 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 2000-2022 period has 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. Under the current most probable forecast, the total water year 2023 unregulated inflow to Lake Powell is projected to be 8.13 maf (85 percent of average).

At the beginning of water year 2024, total system storage in the Colorado River Basin was 25.27 maf (43 percent of 58.48 maf total system capacity). This is an increase of 5.72 maf over the total storage at the beginning of water year 2023 when total system storage was 19.55 maf (33 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). Based on current inflow forecasts, the current projected end of water year 2024 total Colorado Basin reservoir storage is approximately 25.18 maf (43.1 percent of total system capacity). The actual end of water year 2024 system storage may vary from this projection, primarily due to uncertainty regarding this season’s runoff and reservoir inflow.


Please contact the Operations Group via e-mail at for additional information.

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Last Updated: 7/11/24