Big Timber #3 Reservoir Report
Nearby: Big Timber #1 Montana #7
Last Updated: December 7, 2025
Big Timber #3, also known as Big Timber Dam, is a privately owned structure located in Rosebud County, Montana.
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Summary
Built in 1956 by the USDA NRCS, this earth dam serves multiple purposes, including fire protection, stock water supply, and a small fish pond. With a height of 18 feet and a length of 275 feet, the dam has a storage capacity of 68 acre-feet and is primarily regulated by the Montana Department of Natural Resources and Conservation.
Situated on TR-McGraw Coulee near Forsyth, Big Timber #3 is classified as a low hazard potential structure with a moderate risk level. Although the dam's condition assessment is currently marked as "Not Rated", it is regularly inspected and maintained by state agencies to ensure its safety and functionality. The spillway type is uncontrolled, and the dam has not undergone any significant modifications since its completion.
Water resource and climate enthusiasts will find Big Timber #3 an intriguing structure with a unique history and purpose. Its location in a picturesque setting in Montana, along with its contribution to fire protection and water supply, makes it an important asset in the region. Although the dam's risk level is moderate, ongoing management and regular inspections help ensure its continued reliability and safety.
Year Completed |
1956 |
Dam Length |
275 |
Dam Height |
18 |
River Or Stream |
TR-MCGRAW COULEE |
Primary Dam Type |
Earth |
Hydraulic Height |
18 |
Drainage Area |
1.41 |
Nid Storage |
68 |
Hazard Potential |
Low |
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.
Big Timber #3