Lost Leg dam
Lost Leg
Lost Leg is a privately owned earth dam located in Rosebud, Montana, along the Tongue River. Built in 1968 by the USDA NRCS, this dam serves multiple purposes including fire protection, stock watering, and creating a small fish pond. With a height of 32 feet and a length of 240 feet, Lost Leg has a storage capacity of 47 acre-feet and a maximum discharge of 200 cubic feet per second.
The dam is classified as having a low hazard potential and a moderate risk level. While it is regulated and permitted by the state of Montana, its condition has not been formally assessed. The spillway is uncontrolled with a width of 18 feet, and the dam has not been modified since its completion. Despite its age, Lost Leg remains a key structure for water resource management in the area, and its importance in fire protection and agricultural activities cannot be understated.
Lost Leg stands as a testament to the enduring legacy of water resource infrastructure in Montana. As a critical component of the local ecosystem, this dam provides essential services to the community while also posing a manageable level of risk. Its construction and maintenance reflect the collaborative efforts of federal and state agencies, highlighting the importance of effective water management practices in the face of changing climate conditions. For water resource and climate enthusiasts, Lost Leg serves as a reminder of the delicate balance between human needs and environmental stewardship in sustaining our precious water resources.
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 Lost Leg -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Tongue R At Birney Day School Br Nr Birney Mt | 278 cfs | → |
| Otter Creek At Ashland Mt | 3 cfs | → |
| Hanging Woman Creek Near Birney Mt | 0 cfs | → |
| Rosebud C At Reservation Bndry Nr Kirby Mt | 6 cfs | → |
| Tongue R Bl Brandenberg Bridge Nr Ashland Mt | 139 cfs | → |
| Tongue River At Tongue R Dam Nr Decker Mt | 268 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lost Leg.
Track Lost Leg 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 Lost Leg
Where does the data for Lost Leg 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 Low 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 Lost Leg.