Turtle-Flambeau Reservoir Report

Last Updated: December 5, 2025

Turtle-Flambeau is a concrete dam located in Iron, Wisconsin, with a fascinating history dating back to its completion in 1926.


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Summary

This dam stands 26 feet tall and spans 9150 feet, creating a reservoir with a storage capacity of 239,000 acre-feet. The dam is situated on the North Fork Flambeau River, within the jurisdiction of the state of Wisconsin, and operated by a Public Utility.

The dam's primary purpose and associated structures are not explicitly stated, but it is regulated by the Federal Energy Regulatory Commission (FERC) and falls under their inspection and enforcement purview. With a spillway width of 57 feet and a maximum discharge capacity of 16,000 cubic feet per second, the dam poses a high hazard potential, prompting a very high risk assessment ranking. The emergency action plan for the dam was last revised in December 2019, indicating ongoing efforts to ensure public safety and preparedness in the event of an emergency.

For water resource and climate enthusiasts, Turtle-Flambeau presents a compelling case study in dam infrastructure management and risk assessment. The dam's historical significance, hydraulic specifications, and regulatory oversight by FERC make it a noteworthy site for further research and exploration. Understanding the intricate balance between water resource management, infrastructure maintenance, and emergency preparedness is crucial in safeguarding both the environment and local communities in the face of changing climate patterns and increasing water-related risks.

Year Completed

1926

Dam Length

9150

Dam Height

26

River Or Stream

North Fork Flambeau

Primary Dam Type

Concrete

Surface Area

13798

Hydraulic Height

18

Drainage Area

666

Nid Storage

239000

Outlet Gates

Tainter (radial) - 3

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

26
       
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.