Vassaus #11 Reservoir Report
Nearby: Sand #2 Philbrick #3
Last Updated: December 5, 2025
Vassaus #11, located in Rosebud, Montana, is a privately owned earth dam completed in 1965 for fire protection, stock, and small fish pond purposes.
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Summary
With a dam height of 20 feet and a storage capacity of 82 acre-feet, this structure serves the South Fork Cottonwood Creek. The dam is under state jurisdiction and regulated by the Montana Department of Natural Resources and Conservation (DNRC), ensuring proper permitting, inspection, and enforcement protocols are in place.
Despite its low hazard potential, Vassaus #11 has not been rated for its current condition, with no recent inspection data available. The dam has a normal storage capacity of 42 acre-feet and a drainage area of significance. With no spillway type specified, the dam's emergency action plan (EAP) status, risk assessment, and management measures are all unknown at this time. While the structure meets state regulatory standards, more detailed information on its current condition and risk potential would be beneficial for water resource and climate enthusiasts interested in the area's water infrastructure.
Year Completed |
1965 |
Dam Length |
125 |
Dam Height |
20 |
River Or Stream |
TR-SOUTH FORK COTTONWOODCR |
Primary Dam Type |
Earth |
Hydraulic Height |
20 |
Nid Storage |
82 |
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.
Vassaus #11