Lake Thibadeau Dam Reservoir Report
Last Updated: December 6, 2025
Lake Thibadeau Dam, located in Hill, Montana, was constructed in 1938 by the U.S.
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Summary
Department of Agriculture for the primary purpose of serving as a Fish and Wildlife Pond. This earth dam stands at a height of 18 feet with a length of 380 feet, providing a storage capacity of 4,445 acre-feet and a surface area of 235 acres. The dam's location on the Rock Coulee-TR river provides a critical habitat for local wildlife and plays a significant role in preserving the area's natural ecosystem.
Despite its historical significance, Lake Thibadeau Dam is currently classified as having a poor condition assessment, with a low hazard potential. The dam's last inspection in September 2020 revealed the need for maintenance and improvement to ensure its long-term stability. With a moderate risk assessment rating of 3, there is a pressing need for risk management measures to be implemented to address potential safety concerns. As a vital resource for water and climate enthusiasts, the preservation and maintenance of Lake Thibadeau Dam are essential to safeguarding the surrounding environment and wildlife habitat.
Year Completed |
1938 |
Dam Length |
380 |
Dam Height |
18 |
River Or Stream |
ROCK COULEE-TR |
Primary Dam Type |
Earth |
Surface Area |
235 |
Hydraulic Height |
18 |
Drainage Area |
2.05 |
Nid Storage |
4445 |
Structural Height |
18 |
Outlet Gates |
Slide (sluice gate) |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
18 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
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. Investigations and studies are necessary.
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.
Not Available
Dams for which the condition assessment is restricted to approved government users.
Hazard Potential Classification
HighDams 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, environment 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.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.
Lake Thibadeau Dam