Introduction
The goal of this analysis is to project the current conditions of Lake Powell forward through the end of April 2027, which reasonably represents the start of the next significant inflows to Lake Powell from snowmelt next spring.
The recent US Bureau of Reclamation news release1US Bureau of Reclamation News Release: Reclamation Acts to Protect Colorado River System During Historic Drought April 17, 2026 illustrates why this analysis is important as we approach the 3,490 / 3,500 ft elevation level at Lake Powell:
If Glen Canyon Dam declines below 3,490 feet, water releases would be only through the river outlet works, which could cause operational issues, uncertainty for users, downstream impacts, instability in regional power and water supplies, and a reduction in power generation.
“Instability in regional power and water supplies” is a gentle bureaucratic phrasing of what is at stake here for tens of millions of people and hundreds of millions of years of biodiversity downstream of Lake Powell and the Glen Canyon Dam.
All inflow and release data used in this analysis is published by the United States Bureau of Reclamation or derived from their published releases. 2US Bureau of Reclamation Lake Powell Hydrodata
Context
The math used here is very simple:
Starting with the current storage of Lake Powell, add projected inflows, add projected upstream reservoir release inflows, and subtract Glen Canyon Dam releases.
All calculations are completed using volume of water in acre-feet.
Lake Powell elevation is determined from the storage value using the Lake Powell bathymetric storage-elevation model published by the United States Geological Survey. 3U.S. Geological Survey Lake Powell topobathymetric study
What is Flaming Gorge?
Flaming Gorge is a reservoir on the Utah / Wyoming border upstream of Lake Powell. From the US Bureau of Reclamation news release:
Through the 2019 Drought Response Operating Agreements, Reclamation is intending to release 660,000 acre-feet to 1 maf from Flaming Gorge Reservoir from April 2026 through April 2027.
Translated, the US Bureau of Reclamation is planning to send up to 1,000,000 acre-feet of water from Flaming Gorge Reservoir to Lake Powell through April 2027. While the act of using releases from Flaming Gorge to bolster Lake Powell is not unprecedented, as a similar drought response also occurred in 20234US Bureau of Reclamation Drought Response Operations Agreement, the 1,000,000 acre-feet slated to be sent downstream is unprecedented. As Flaming Gorge has considerably less capacity than Lake Powell, releases disproportionately lower the lake elevation at Flaming Gorge in relation to gains in elevation at Lake Powell.
Why is 2002 relevant?
Before 2026, 2002 represented the lowest snowpack in the upper Colorado River basin as well as the lowest snowmelt cycle unregulated inflows to Lake Powell.
Climatically, 2026 is a historic outlier in the upper Colorado River basin, combining all-time low snowpack with all-time high temperatures. Where 2002 was previously the absolute floor for inflows, this year it represents a highly optimistic ceiling for inflows to Lake Powell.
The ledger and chart below use 2002 for context as an optimistic starting point for inflows from the 2026 water cycle.
What Are Unregulated Inflows?
Unregulated inflows to Lake Powell are the estimated inflow volumes that would occur independent of the various dams and reservoirs that make up the Colorado River Storage Project components upstream of Lake Powell.
These include operations at Flaming Gorge Dam on the Green River, Navajo Dam on the San Juan River, and the Aspinall Unit including the Blue Mesa Dam on the Gunnison River.
The news release from the US Bureau of Reclamation declared:
No additional releases from the other upstream initial units of the Colorado River Storage Project Act—Blue Mesa and Navajo reservoirs—are planned at this time, due to their low water levels and poor forecasted inflows.
Using unregulated inflows to Lake Powell along with the published drought response release volumes from Flaming Gorge provides a reasonably clear picture of the components for inflow to Lake Powell through April 2027.
Projection
How To Use This Chart
Current Lake Powell status
The readout at the top shows the latest available Lake Powell elevation and storage. The chart and table below start from that current observed condition.
Remaining water cycle inflow
This control sets projected inflow to Lake Powell from now through the end of July 2026. Manual lets you distribute a chosen total across the remaining runoff season. 2002 uses the remaining April-July unregulated inflow volume from water year 2002.
Post-runoff inflow
This control sets projected inflow from August 2026 through April 2027. Manual distributes a chosen total evenly across that period. 2002-2003 uses observed unregulated inflow volumes from August-September 2002 and October-April 2003. Avg dry years uses the average of comparable dry-year unregulated inflow volumes.
Flaming Gorge DROA release
This slider adds the planned drought-response release volume from Flaming Gorge Reservoir to Lake Powell over the same projection period. It is separate from the unregulated inflow assumptions.
Glen Canyon Dam release
This slider sets the monthly release from Glen Canyon Dam used by the ledger. The default of 500,000 AF/month corresponds to a 6.0 MAF/year release rate, and the control allows adjustment from 4.5 MAF/year to 6.5 MAF/year.
Chart and table
The line chart shows projected Lake Powell storage and elevation through April 2027. The table below shows the same monthly accounting in acre-feet: inflow, upstream reservoir inflow, release, resulting storage, and monthly storage change.
Current Lake Powell Conditions
Reference Snowpack, Temperature, and Streamflow charts
Upper Colorado River Basin Snowpack (SNOTEL)
Upper Colorado River Basin Snowpack (SNODAS)
Upper Colorado River Basin Snowpack by Elevation
Upper Colorado River Basin Average Temperatures
Colorado River Basin Forecast Center Lake Powell Inflow Projections
Upper Colorado River Basin Major Tributary Streamflows