Bynum Reservoir Dam Reservoir Report

Last Updated: December 5, 2025

Bynum Reservoir Dam, located in Teton County, Montana, is a vital part of the region's water resource infrastructure.


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Summary

Completed in 1926, this earth dam stands at a height of 60 feet and has a maximum storage capacity of 107,000 acre-feet, primarily used for irrigation purposes. With a surface area of 3,200 acres and a drainage area of 32.6 square miles, the dam plays a crucial role in regulating water flow and providing water for agricultural activities in the area.

Managed by a private owner, the Bynum Reservoir Dam is regulated and inspected by the Montana Department of Natural Resources and Conservation (DNRC) to ensure its safety and compliance with state regulations. Despite being classified as having a high hazard potential, the dam's condition assessment in May 2020 deemed it to be satisfactory. Regular inspections every five years help to monitor the dam's structural integrity and ensure that it continues to serve its essential function in the community.

With its strategic location on Miller Creek and its contribution to the irrigation needs of the region, Bynum Reservoir Dam is a critical piece of infrastructure in Montana's water resource management. As climate change continues to impact water availability and usage patterns, the efficient operation and maintenance of dams like Bynum Reservoir become increasingly important in ensuring sustainable water management practices for the future.

Year Completed

1926

Dam Length

3700

Dam Height

60

River Or Stream

MILLER CREEK

Primary Dam Type

Earth

Surface Area

3200

Hydraulic Height

60

Drainage Area

32.6

Nid Storage

107000

Hazard Potential

High

Foundations

Rock

Nid Height

60
       
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.