Hearst Lake Reservoir Report

Last Updated: December 5, 2025

Hearst Lake, located in Deer Lodge, Montana, is a stunning water resource managed by the local government for water supply purposes.


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Summary

The dam at Hearst Lake, completed in 1898, stands at a height of 9 feet and has a storage capacity of 140 acre-feet. Situated along the Grays Gulch river, this reservoir offers a serene escape and plays a crucial role in supporting the water needs of the surrounding community.

With a low hazard potential and a condition assessment that is currently not rated, Hearst Lake serves as a reliable water source in the region. Despite its age, the dam at Hearst Lake remains structurally sound and well-maintained, with state regulatory agencies ensuring proper inspection, permitting, and enforcement measures are in place. As water resource and climate enthusiasts, the tranquil beauty and functional significance of Hearst Lake make it a worthwhile destination for exploration and appreciation of sustainable water management practices.

Year Completed

1898

Dam Length

300

Dam Height

9

River Or Stream

GRAYS GULCH

Primary Dam Type

Other

Hydraulic Height

9

Nid Storage

140

Hazard Potential

Low

Nid Height

9
       
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.