Minong Flowage Reservoir Report

Last Updated: December 5, 2025

Minong Flowage, located in Washburn, Wisconsin, is a gravity dam completed in 1936 for the primary purpose of recreation.


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Summary

With a structural height of 29 feet and a length of 300 feet, this dam has a storage capacity of 23,000 acre-feet and covers a surface area of 1,609 acres. The dam is regulated by the Wisconsin Department of Natural Resources and undergoes regular inspections to ensure its safety and functionality.

The dam's spillway is controlled, and the hazard potential is rated as high with a fair condition assessment. The risk assessment for Minong Flowage is very high, indicating potential risks that need to be managed effectively. While the dam has been modified in the past, its emergency action plan and risk management measures are yet to be fully documented. Despite these challenges, the dam continues to serve its purpose of providing recreational opportunities for the local community and visitors.

Overall, Minong Flowage is a critical water resource in the area, supporting hydroelectric power generation and providing a popular spot for recreational activities. With its rich history dating back to the 1930s, the dam stands as a testament to effective water resource management in Wisconsin. Enthusiasts of water resources and climate will find Minong Flowage to be a fascinating subject of study, with its unique design, regulatory oversight, and ongoing efforts to ensure public safety and environmental sustainability.

Years Modified

1937 - Other

Year Completed

1936

Dam Length

300

Dam Height

29

River Or Stream

TOTAGATIC

Primary Dam Type

Gravity

Surface Area

1609

Hydraulic Height

18

Drainage Area

320

Nid Storage

23000

Structural Height

29

Hazard Potential

High

Nid Height

29
       
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.