B-Downs #8 Reservoir Report
Nearby: R Downs #7 Christensen L&C #1
Last Updated: December 5, 2025
B-Downs #8, also known as Downs Dam, is a privately owned structure located in Big Horn, Montana, along the Williams Coulee river.
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Summary
Built in 1974 by the USDA NRCS, this earth-type dam stands at 20 feet high and has a length of 650 feet. Its primary purpose is for fire protection, stock, or as a small fish pond, providing a storage capacity of 474 acre-feet.
Despite being regulated by the Montana DNRC and meeting state permitting, inspection, and enforcement requirements, B-Downs #8 poses a low hazard potential with a moderate risk assessment rating of 3. The dam has not been rated for condition assessment, and its emergency action plan readiness, inundation maps, and risk management measures are not documented. With its location in a sparsely populated area, the dam serves as a vital water resource for local agricultural and wildlife needs.
Water resource and climate enthusiasts may find B-Downs #8 an intriguing case study in dam infrastructure management. While the dam's risk assessment suggests a moderate level of concern, its low hazard potential and limited associated structures indicate a relatively stable condition. Monitoring the dam's maintenance and emergency preparedness efforts could provide valuable insights into sustainable water resource management practices in rural Montana.
Year Completed |
1974 |
Dam Length |
650 |
Dam Height |
20 |
River Or Stream |
WILLIAMS COULEE |
Primary Dam Type |
Earth |
Hydraulic Height |
20 |
Drainage Area |
5.47 |
Nid Storage |
474 |
Hazard Potential |
Low |
Nid Height |
20 |
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.
B-Downs #8