Reservoirs
Below normalBoysen Reservoir water level
Live reservoir storage and water level in Wind-Bighorn-Missouri basin, Wyoming
Data through Sep 23, 2026 · source last checked Oct 1, 2026 · page revised Sep 24, 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
- Sep 23, 2026
- Update frequency
- Daily
Now 492,554 af, 23% below the 5-yr median, 66% of capacity.
Boysen storage stands at 492,554 af, down 5.2% year over year and 23% below the 5-year median. The reservoir gained 1.0% on the week.
| Period | Current | Prior | Change |
|---|---|---|---|
| Week over week | 492,554 af | 487,467 af | +1.0% |
| Month over month | 492,554 af | 507,804 af | -3.0% |
| Year over year | 492,554 af | 519,803 af | -5.2% |
| vs 5-yr median | 492,554 af | 638,172 af | -22.8% |
| Measure | Value |
|---|---|
| Latest reading, Sep 23, 2026 | 4,709.99 ft above sea level |
| Change from a week earlier | +0.37 ft |
| Change from a year earlier | -1.93 ft |
| 5-yr median for the date | 4,719.42 ft |
| Below full pool | 7.01 ft |
| Five-year low | 4,709.54 ft (Sep 19, 2026) |
| Five-year high | 4,728.41 ft (Jun 24, 2023) |
| 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 Sep 15, 2026
Boysen storage stands at 488,150 af, down 5.3% over the past month and 7.7% year-over-year. The reservoir is at 66% of capacity and 24% below its 5-year median.
Week of Sep 2, 2026
Boysen storage is 500,621 af, down 5.4% on the month and 8.6% year over year. The reservoir runs 24% below the 5-year median.
Week of Aug 26, 2026
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.
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.
About Boysen Reservoir
Boysen Reservoir's water level is 4,709.99 feet above sea level as of Sep 23, 2026, 7.01 feet below full pool (4,717 feet), with 492,554 acre-feet in storage (66% of capacity). That is 0.37 feet higher than a week earlier and 1.93 feet lower than a year earlier.
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 486,370 af to 810,589 af.
Boysen Reservoir is one of the 21 major reservoirs this site totals each day. For the combined picture, western reservoir levels carries the storage of all 21 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 and the elevation table tracks the water surface in feet, so read storage against total capacity for how full the reservoir is, and the elevation 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.