Hebgen Lake water level — Montana
Hebgen Lake in Montana was last measured at 6,531.22 ft (datum NGVD29), as of Aug 31, 2026, 1:45 AM (UTC-06:00) (USGS Water Services). Over its recent trend window the level has been falling (−1.2 ft). This reading is provisional and subject to revision.
- % of conservation pool full
- Not reported
- Storage
- Not reported
- Recent trend
- ↓Falling
−1.2 ft over the trend window
Recent trend
Readings this station published between Jun 2, 2026 and Aug 31, 2026 — a 89-day window — downsampled for display.
Data: USGS Water Services (waterservices.usgs.gov) and USACE CWMS Data (cwms-data.usace.army.mil), retrieved 2026-08-31. Both public domain (a work of the U.S. Government, 17 U.S.C. §105).
Source: USGS site 06038000, retrieved Aug 31, 2026, 8:24 AM (UTC+00:00). Official page for this lake →
About this gauge's record
This site's drainage basin covers approximately 904 sq mi of contributing watershed.
The dam behind Hebgen Lake
Hebgen Lake is held back by Hebgen Dam , an earthfill embankment, holding the pool back by sheer mass and an impervious core rather than by the strength of concrete , standing 120 ft high and running 721 ft along its crest , built across Madison River in Gallatin County , near Ennis, MT . It was completed in 1915 , and is owned by NorthWestern Energy (a private owner) .
Its recorded primary purpose is hydroelectric — releases follow generation schedules, so the level can move on a daily cycle that has nothing to do with drought . It also serves hydroelectric;recreation;water supply;flood risk reduction.
Its spillway is gated, so the operator can hold the pool above the spillway crest and meter what leaves. The spillway opening is 47 ft wide. Its outlet works use slide (sluice gate)4.
NID classes it high hazard potential. That describes what a failure would cost downstream — loss of life would be expected — and says nothing about how likely a failure is, or what condition the dam is in. Its most recent condition assessment was satisfactory — no deficiencies recognised for expected loading. That assessment is dated 04/11/2023.
At its normal pool the reservoir covers about 13,000 acres. NID records a maximum storage of 525,620 acre-ft against a normal storage of 386,000 acre-ft. Its maximum discharge capacity is 4,400 cubic feet per second.
Dam facts: National Inventory of Dams record MT00134 , filed by Federal Energy Regulatory Commission — U.S. Army Corps of Engineers, public domain. Water levels above come from USGS Water Services and are a separate source. (How this dam was matched to this gauge →)
How Hebgen Lake compares nearby
All 6 nearby lakes with a current trend are also falling, suggesting a regional pattern rather than an operation specific to this dam.
Nearby lakes
The six nearest published lakes by centroid distance (great-circle) — cross-state neighbors included.
| Lake | State | Level | Distance |
|---|---|---|---|
| Georgetown Lake | MT | 6,429.02 ft | 213 km |
| Bear Lake | UT | 5,919.20 ft | 322 km |
| Big Sandy Reservoir | WY | 6,737.68 ft | 329 km |
| Pineview Dam & Reservoir | UT | 4,854.20 ft | 403 km |
| Lost Creek Reservoir | UT | 5,946.68 ft | 409 km |
| Great Salt Lake | UT | 4,189.90 ft | 412 km |
Frequently asked questions
- What is the current water level of Hebgen Lake?
- As of Aug 31, 2026, 1:45 AM (UTC-06:00), the pool elevation was 6,531.22 ft (datum NGVD29), provisional and subject to revision. See the trend chart above for the recent direction.
- Is Hebgen Lake full right now?
- Its managing agency does not publish a %-of-conservation-pool-full figure for this lake, so we show the bare level rather than estimate one.
- Where does this data come from?
- From USGS site 06038000, retrieved Aug 31, 2026, 8:24 AM (UTC+00:00).
More in Montana
See every lake tracked in Montana, or read the methodology behind these figures.