Empire Mine Tailings Basin Dam Reservoir Report

Last Updated: December 5, 2025

The Empire Mine Tailings Basin Dam, also known as Etb #2 & West Dams, F Dam, is a privately owned structure located in Gwinn, Michigan.


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Summary

This significant dam was completed in 1975 and serves the primary purpose of containing tailings from mining operations. With a height of 163 feet and a hydraulic height of 143 feet, this earth dam spans a length of 27,800 feet and has a storage capacity of 117,000 acre-feet.

Managed by the Mine Safety and Health Administration, the dam is state-regulated and undergoes regular inspections to ensure its structural integrity. The hazard potential is rated as significant, but the condition assessment as of September 2019 was deemed satisfactory. However, the risk assessment is classified as very high (1), highlighting the importance of proper risk management measures and emergency preparedness.

Situated near Green Creek in Marquette County, the Empire Mine Tailings Basin Dam poses a crucial role in the regional water resource infrastructure. Its controlled spillway and large storage capacity make it a vital component in managing water flow and potential discharge events. As climate change continues to impact water resources, the maintenance and regulation of such dams become increasingly critical for ensuring public safety and environmental protection in the face of evolving hydrological conditions.

Year Completed

1975

Dam Length

27800

Dam Height

163

River Or Stream

Green Creek

Primary Dam Type

Earth

Surface Area

940

Hydraulic Height

143

Drainage Area

5.2

Nid Storage

117000

Structural Height

163

Hazard Potential

Significant

Nid Height

163
       
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.