Hebgen Dam dam
Hebgen Dam
Hebgen Dam, located in Ennis, Montana, is a captivating structure with a primary purpose of generating hydroelectric power. Completed in 1915, this earth dam stands at a height of 88 feet and has a structural height of 120 feet, with a reservoir capacity of 525,620 acre-feet. The dam also serves purposes such as flood risk reduction, recreation, and water supply for the surrounding area.
With a drainage area of 905 square miles and a maximum discharge capacity of 4,400 cubic feet per second, Hebgen Dam plays a crucial role in managing water resources in the region. The dam features a controlled spillway with a width of 47 feet and slide gates for outlet control. Despite its high hazard potential, the dam is inspected regularly by the Federal Energy Regulatory Commission to ensure its safety and reliability.
Surrounded by the scenic beauty of the Madison River and serving as a source of renewable energy, Hebgen Dam stands as a symbol of efficient water resource management and sustainable energy generation. Its strategic location and design make it a vital piece of infrastructure that contributes to the overall well-being of the community while preserving the natural environment.
Plan around the weather
Same NOAA / yr.no feed Snoflo's iOS app uses. Watch the precipitation column on the meteogram -- rain on the basin upstream typically lifts inflow 24-72 hours later.
Next 5 days, hour by hour
Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.
5-day forecast table
Every 3 hours, broken out across temperature, snow, rain, humidity, and wind. Each cell is colour-coded relative to the column min/max.
| Time | Condition | Temp (°F) | Snow (in) | Rain (in) | Humidity (%) | Wind (mps) | Wind dir |
|---|---|---|---|---|---|---|---|
| Loading detailed forecast… | |||||||
15-day temperature & precipitation
Daily temperatures, snow, and rain projected over the next two weeks.
Nearby streamflow gauges
USGS streamgauges around Hebgen Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Madison River Bl Hebgen Lake Nr Grayling Mt | 825 cfs | → |
| Madison River At Kirby Ranch Nr Cameron Mt | 1,140 cfs | → |
| Henrys Fork Nr Lake Id | 100 cfs | → |
| Madison River Near West Yellowstone Mt | 349 cfs | → |
| Red Rock Cr Ab Lakes Nr Lakeview Mt | 45 cfs | → |
| Big Springs At Big Springs Id | 128 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Hebgen Dam.
Boat launches
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Campgrounds
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Fishing spots
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River runs
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More reservoirs
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About Hebgen Dam
Where does the data for Hebgen Dam come from?
Structural and regulatory data come from the U.S. Army Corps of Engineers' National Inventory of Dams (NID). Weather forecast comes from NOAA / yr.no -- the same feed Snoflo's iOS app uses.
How often is the report updated?
NID structural data refreshes annually as the Corps publishes updated assessments. The weather forecast refreshes throughout the day.
What does the High hazard rating mean?
The Corps of Engineers' hazard potential classification grades probable consequences if the dam fails: High = probable loss of human life; Significant = no probable loss of human life but possible economic loss / environmental damage; Low = no probable loss of human life, only minor economic / environmental losses. See the Dam Data Reference card below for the full definitions.
What's "% of normal"?
The current storage value compared to the historical average storage on this calendar day. 100% = right on average; values above 100% mean above-normal storage (wet year); values below mean below-normal (dry year or drought).
Can I get alerts when storage crosses a threshold?
Yes -- alerts are managed in the Snoflo iOS app. Favorite this dam, set a threshold, and you'll get a push the moment conditions cross.
Dam data reference
Condition Assessment
- Satisfactory
- No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
- Fair
- No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action.
- Poor
- A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency.
- Unsatisfactory
- A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
- Not Rated
- The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Hazard Potential Classification
- High
- Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
- Significant
- Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
- Low
- Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
- Undetermined
- Dams for which a downstream hazard potential has not been designated or is not provided.