Killen Dam Reservoir Report

Nearby: Trout Vt #1

Last Updated: December 6, 2025

Killen Dam, located in Forsyth, Montana, is a privately owned structure built in 1970 for fire protection, stock, and as a small fish pond.


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Summary

Standing at 29 feet tall and stretching 950 feet in length, the dam holds a maximum storage capacity of 83 acre-feet and serves the primary purpose of protecting the surrounding area from potential hazards. Situated along the TR-South Fork Sunday Creek, the dam is regulated by the Montana Department of Natural Resources and Conservation (DNRC), ensuring proper inspection, permitting, and enforcement measures are in place.

With a low hazard potential and a moderate risk assessment rating, Killen Dam provides essential water resource management for the local community. The dam features an uncontrolled spillway with a width of 50 feet, capable of discharging up to 126 cubic feet per second in times of excess water flow. While the dam has not been rated for condition assessment, it continues to serve its intended purposes effectively. Despite its private ownership, Killen Dam plays a crucial role in maintaining water security and supporting ecological balance in the region.

As an integral part of the water infrastructure in Rosebud County, Killen Dam serves as a vital resource for the community, offering protection against potential emergencies and supporting local water needs. While its condition assessment remains unrated, the dam's low hazard potential and moderate risk assessment signify its importance in water resource management. With the oversight of the DNRC and consistent monitoring, Killen Dam stands as a testament to effective water resource governance in Montana.

Year Completed

1970

Dam Length

950

Dam Height

29

River Or Stream

TR-SOUTH FK SUNDAY CREEK

Primary Dam Type

Earth

Drainage Area

2.03

Nid Storage

83

Hazard Potential

Low

Nid Height

29
       
Seasonal Comparison

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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.