Green Mountain dam
Green Mountain
Green Mountain, located in Summit County, Colorado, is a federal-owned dam managed by the Bureau of Reclamation for hydroelectric power generation, irrigation, and recreation purposes. Completed in 1942, this Earth dam stands at 309 feet tall and spans 1150 feet across the Blue River, with a storage capacity of 161,850 acre-feet and a surface area of 2125 acres. The dam's spillway, controlled by slide and valve gates, has a width of 75 feet, and the maximum discharge capacity is 27,000 cubic feet per second.
With a high hazard potential and a very high risk assessment rating, Green Mountain is closely regulated and inspected by the Bureau of Reclamation to ensure its structural integrity and the safety of downstream communities. The dam's emergency action plan was last revised in January 2020, and although the condition assessment is not available, regular inspections are conducted to monitor its performance. Despite being a critical piece of infrastructure, the dam poses a potential risk due to its age and the surrounding environment, emphasizing the importance of ongoing risk management measures to mitigate any potential hazards.
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.
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 Green Mountain -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Blue River Below Green Mountain Reservoir | 63 cfs | → |
| Williams Fork Near Parshall | 73 cfs | → |
| Colorado River Near Kremmling | 227 cfs | → |
| Williams Fork Below Williams Fork Reservoir | 18 cfs | → |
| Piney River Below Piney Lake | 71 cfs | → |
| Piney River Near State Bridge | 129 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Green Mountain.
Boat launches
- Co 9 Summit County
- Confluence Rec Site Boat Ramp
- Radium Rec Site Boat Ramp
- State Bridge River Access
- State Bridge Boat Ramp
- Eagle Valley Trail Avon
Campgrounds
- Elliott Creek
- Elliott Creek Campground
- Willows
- Cow Creek North Campground
- Cow Creek South Campground
- Cataract Creek Campground
Fishing spots
- Green Mountain Reservoir
- Lower Cataract Lake
- Upper Cataract Lake
- Williams Fork Reservoir
- Wolford Mountain Reservoir
- Nottingham Lake
Paddle runs
More reservoirs
Track Green Mountain in the Snoflo app
Save this dam as a favorite and get the local NOAA / yr.no forecast plus regional flow context wherever you are.
About Green Mountain
Where does the data for Green Mountain 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 above 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.
Other water bodies near here
Snoflo-tracked reservoirs and dams within driving distance of Green Mountain.