Seven Mile Reservoir Report

Last Updated: December 5, 2025

Seven Mile, a gravity dam located in Eagle River, Wisconsin, harnesses the power of Seven Mile Creek for hydroelectric purposes.


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Summary

Completed in 1908, this historic structure stands at 9.7 feet tall and spans 282 feet in length, with a storage capacity of 9,573 acre-feet. Managed by the Federal Energy Regulatory Commission, Seven Mile serves to reduce flood risks and generate clean energy for the region.

Despite being categorized as low hazard potential, Seven Mile is subject to regular inspections to ensure its structural integrity and safety. With a controlled spillway and a Tainter radial gate outlet, this dam plays a crucial role in managing water flow and protecting downstream areas. The risk assessment for Seven Mile indicates a very high risk level (1), highlighting the importance of effective risk management measures to safeguard the surrounding community and environment.

Overall, Seven Mile represents a significant piece of Wisconsin's water infrastructure, combining historical relevance with modern functionality. As climate change continues to impact water resources, the efficient operation and maintenance of dams like Seven Mile are essential for ensuring water security and sustainability in the face of evolving environmental challenges.

Year Completed

1908

Dam Length

282

Dam Height

9.7

River Or Stream

Seven Mile Creek

Primary Dam Type

Gravity

Drainage Area

12.1

Nid Storage

9573

Outlet Gates

Tainter (radial) - 1

Hazard Potential

Low

Foundations

Soil

Nid Height

10
       
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.