Reservoirs
Below normalBoysen Reservoir water level
Live reservoir storage and water level in Wind-Bighorn-Missouri basin, Wyoming
Data through Aug 26, 2026 · source last checked Aug 27, 2026 · page revised Aug 27, 2026
Cite
- Storage
About this data
- Source
- US Bureau of Reclamation RISE; California reservoirs via CA DWR CDEC
- Series
- End-of-day reservoir storage
- Geography
- Boysen Reservoir water level
- Unit
- acre-feet
- Calculation
- Daily reading
- Last observation
- Aug 26, 2026
- Update frequency
- Daily
Now 505,259 af, 24% below the 5-yr median, 68% of capacity.
Boysen storage fell to 505,259 af, down 1.5% on the week and 5.5% over the month. The reservoir sits 24% below its 5-year median at 68% of capacity.
| Period | Current | Prior | Change |
|---|---|---|---|
| Week over week | 505,259 af | 512,779 af | -1.5% |
| Month over month | 505,259 af | 534,527 af | -5.5% |
| Year over year | 505,259 af | 553,938 af | -8.8% |
| vs 5-yr median | 505,259 af | 666,064 af | -24.1% |
| Measure | Value | Source |
|---|---|---|
| Full pool elevation | 4,717 ft above sea level (top of active conservation pool) | USBR |
| Maximum depth at the dam | 117 ft | USBR |
| Surface area at full pool | 19,560 acres | USACE NID |
| Total capacity | 741,594 acre-feet | USBR |
Previous weeks
Week of Aug 19, 2026
Boysen storage is 512,779 af, down 4.7% on the month and 9.0% year-over-year. The reservoir sits 24% below its 5-year median.
An earlier week
Boysen storage fell to 519,514 af, down 4.7% over the month and 9.3% year over year. The reservoir sits 24% below its 5-year median, at 70% of capacity.
Week of Aug 13, 2026
Storage at Boysen fell to 522,695 af, down 4.7% on the month and 9.3% year-over-year. The reservoir sits 23% below the 5-year median.
About Boysen Reservoir
Boysen Dam holds the Wind River at the upstream mouth of Wind River Canyon, a Pick-Sloan unit above Thermopolis in central Wyoming. Reclamation operates it for irrigation, flood control, power, and sediment retention. Below the canyon the same river changes names, becoming the Bighorn.
Total capacity is 741,594 af, over the past five years storage has ranged from 498,247 af to 810,589 af.
Boysen Reservoir is one of the 20 major reservoirs this site totals each day, and one of several it tracks in the Wind-Bighorn-Missouri basin. For the combined picture, western reservoir levels carries the storage of all 20 on one chart, which is the number to watch when the question is about the West as a whole rather than about this project.
Those figures describe the reservoir at full pool, not today. The chart at the top of this page tracks storage in acre-feet rather than water depth, so read the current figure against total capacity for how full the reservoir is, and against the full pool elevation and maximum depth for the size of the water column behind the dam. The two do not move together one for one: a reservoir narrows as it deepens, so one holding half its capacity still stands more than half as deep.
Sources: full pool elevation and maximum depth from the Bureau of Reclamation; surface area from the Army Corps' National Inventory of Dams; total capacity from the Bureau of Reclamation.