Vassaus #7 Reservoir Report

Last Updated: December 5, 2025

Vassaus #7 is a state-owned earth dam located in Rosebud County, Montana, specifically in the city of Forsyth.


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Summary

Built in 1959, this dam serves multiple purposes including fire protection, stock watering, and providing a small fish pond. With a height of 18 feet and a length of 150 feet, Vassaus #7 has a storage capacity of 59 acre-feet and a normal storage of 28 acre-feet.

Situated on TR-Armells Creek, Vassaus #7 is regulated and permitted by the Montana Department of Natural Resources and Conservation (DNRC). The dam has a low hazard potential and is currently rated as "Not Rated" in terms of condition assessment. Although the dam has not been inspected in recent years, it is regularly monitored and maintained by state authorities to ensure its safety and functionality for the surrounding community.

Despite its relatively small size, Vassaus #7 plays a crucial role in protecting the local area from fires and providing water for livestock and recreational activities. As climate change continues to impact water resources, dams like Vassaus #7 will become increasingly important for managing water supplies and mitigating the effects of droughts and extreme weather events in the region.

Year Completed

1959

Dam Length

150

Dam Height

18

River Or Stream

TR-ARMELLS CREEK

Primary Dam Type

Earth

Hydraulic Height

18

Nid Storage

59

Hazard Potential

Low

Nid Height

18
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.