Big Timber #1 Reservoir Report
Nearby: Big Timber #3 Gearhart #13
Last Updated: December 7, 2025
Big Timber #1, also known as Big Timber Reservoir #1, is a private water resource located in Rosebud County, Montana.
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Summary
Constructed in 1950 by the USDA NRCS, this earth dam stands at a height of 15 feet and serves multiple purposes including fire protection, stock watering, and small fish pond habitat. With a storage capacity of 54 acre-feet, this reservoir on McGraw Coulee has a low hazard potential and is regulated by the Montana Department of Natural Resources and Conservation.
Situated in Forsyth, Montana, Big Timber #1 plays a crucial role in water management and conservation efforts in the region. With a drainage area of 3.59 square miles and a maximum discharge of 100 cubic feet per second, this reservoir provides essential water resources for agricultural and wildlife needs. Although the condition assessment is currently not rated, the risk assessment for this structure is moderate, highlighting the importance of ongoing monitoring and maintenance to ensure its long-term functionality and safety.
As a key component of the local water infrastructure, Big Timber #1 underscores the intersection of water resource management and climate resilience. With its strategic location in Congressional District 00 and under the oversight of the Omaha District of the US Army Corps of Engineers, this reservoir exemplifies the collaboration between federal, state, and private entities to safeguard water resources for the community. The presence of the uncontrolled spillway and the moderate risk assessment emphasize the need for proactive risk management measures to address potential hazards and ensure the sustainable use of this vital water source.
Year Completed |
1950 |
Dam Length |
150 |
Dam Height |
15 |
River Or Stream |
MCGRAW COULEE |
Primary Dam Type |
Earth |
Hydraulic Height |
15 |
Drainage Area |
3.59 |
Nid Storage |
54 |
Hazard Potential |
Low |
Nid Height |
15 |
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 #1