Hemlock Falls Reservoir Report

Last Updated: December 5, 2025

Hemlock Falls, a hydroelectric dam located in Iron Mountain, Michigan, is a concrete gravity dam with a height of 34 feet and a hydraulic height of 30.1 feet.


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Summary

Constructed in 1953, it serves as a crucial source of renewable energy in the region, with a primary purpose of hydroelectric power generation. The dam has a normal storage capacity of 410 acre-feet and a maximum discharge rate of 16,000 cubic feet per second, ensuring efficient water resource management in the area.

Managed by the Federal Energy Regulatory Commission, Hemlock Falls not only contributes to clean energy production but also provides recreational opportunities for the community. With a controlled spillway width of 201 feet and three Tainter (radial) outlet gates, the dam has a low hazard potential and is inspected every three years to ensure its structural integrity. Despite a very high risk assessment rating, the dam's risk management measures are not specified, highlighting the need for continued monitoring and maintenance to mitigate potential risks and safeguard the surrounding environment.

In the picturesque setting of the Michigamme River, Hemlock Falls stands as a testament to sustainable energy development and water resource conservation. Its historical significance and technological advancements make it a noteworthy site for water resource and climate enthusiasts seeking to explore the intersection of hydroelectric power generation and environmental stewardship in the Great Lakes region.

Year Completed

1953

Dam Length

409

Dam Height

34

River Or Stream

Michigamme River

Primary Dam Type

Concrete

Surface Area

75

Hydraulic Height

30.1

Drainage Area

665

Nid Storage

410

Structural Height

45

Outlet Gates

Tainter (radial) - 3

Hazard Potential

Low

Nid Height

45
       
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.