East Fork Dam dam
East Fork Dam
East Fork Dam, located in Lewistown, Montana, is a key structure designed by the USDA NRCS for flood risk reduction and recreation purposes. Completed in 1974, this earth dam stands at a height of 62 feet and has a structural height of 93 feet, providing a normal storage capacity of 1700 acre-feet for the East Fork Big Spring Creek. With a drainage area of 60.8 square miles and a maximum discharge of 28500 cubic feet per second, the dam plays a crucial role in managing water resources in the region.
This high-hazard potential dam with a satisfactory condition assessment is regulated by the DNRC and undergoes regular inspections every 5 years, with the last assessment conducted in June 2020. Despite its risk level being moderate, the dam has no Emergency Action Plan (EAP) in place, raising concerns about preparedness for potential emergencies. With a spillway width of 400 feet and uncontrolled outlet gates, East Fork Dam continues to be a significant feature in the water resource management and climate adaptation efforts in Fergus County, Montana.
Surrounded by the natural beauty of Fergus County, East Fork Dam offers recreational opportunities while serving as a critical infrastructure for flood control. Its stone core and soil foundation contribute to the dam's resilience, ensuring the safety of nearby communities. As climate change impacts intensify, the maintenance and management of East Fork Dam will be crucial in safeguarding the region's water resources and enhancing resilience to extreme weather events.
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 East Fork Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Musselshell River At Harlowton Mt | 176 cfs | → |
| Musselshell River Ab Mud Cr Nr Shawmut Mt | 60 cfs | → |
| Judith River Nr Mouth | 390 cfs | → |
| Musselshell River Near Roundup Mt | 102 cfs | → |
| Missouri River Near Landusky Mt | 6,360 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near East Fork Dam.
⛺ Campgrounds
- East Fork Reservoir Campground
- Kiwanis Park - Lewiston
- Crystal Lake Campground
- Crystal Lake
- Crystal Lake Cabin
- Timber Creek Dispersed Campground
🎣 Fishing spots
- Lower Hansen Reservoir
- Mccartney Creek
- East Fork Cottonwood Creek
- Upper Carters Pond
- Ackley Lake Feeder Canal
- Warm Spring Creek
🛶 Paddle runs
More paddle runs →Track East Fork Dam 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 East Fork Dam
Where does the data for East Fork 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 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 East Fork Dam.