Bob #3 Reservoir Report
Nearby: Beecher #6 Smith Ranch 2
Last Updated: December 6, 2025
Bob #3 is a privately owned earth dam located in Cohagen, Montana, along the Knudson Coulee stream.
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Summary
Built in 1949, this dam serves multiple purposes including fire protection, stock watering, and a small fish pond. With a height of 20 feet and a storage capacity of 62 acre-feet, Bob #3 has a low hazard potential and is regulated by the Montana Department of Natural Resources and Conservation (DNRC).
Situated in Garfield County, Bob #3 is managed under state jurisdiction with state permitting, inspection, and enforcement in place. The dam is designed to withstand hydraulic pressures up to 20 feet and has a length of 180 feet. Despite not being rated for condition assessment, the dam is considered to have low risk and does not have an Emergency Action Plan (EAP) in place. With its primary purpose being fire protection and stock watering, Bob #3 plays a vital role in water resource management in the region.
Although Bob #3 does not fall under the jurisdiction of the US Army Corps of Engineers, it is a significant structure for the local community in Cohagen. With its historical significance and multi-functional use, this earth dam stands as a testament to the importance of water resource management and climate resilience in the area.
Year Completed |
1949 |
Dam Length |
180 |
Dam Height |
20 |
River Or Stream |
KNUDSON COULEE |
Primary Dam Type |
Earth |
Hydraulic Height |
20 |
Nid Storage |
62 |
Hazard Potential |
Low |
Nid Height |
20 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Nelson Creek Near Van Norman Mt
|
33cfs |
Yellowstone River At Forsyth Mt
|
5430cfs |
Musselshell River At Mosby Mt
|
12cfs |
Flatwillow Creek Near Mosby Mt
|
17cfs |
Yellowstone River At Miles City Mt
|
8100cfs |
Tongue River At Miles City Mt
|
263cfs |
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.
Bob #3