Tomahawk Left Detached Embankment Reservoir Report

Last Updated: December 6, 2025

The Tomahawk Left Detached Embankment is a key structure in Lincoln, Wisconsin, serving the purpose of hydroelectric power generation and recreation on the Wisconsin River.


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Summary

Completed in 1938, this earth dam stands at a height of 20 feet with a hydraulic height of 10.5 feet, providing a storage capacity of 15,180 acre-feet and covering a surface area of 2,773 acres. With a low hazard potential and a high risk assessment rating of 2, this dam is under the jurisdiction of the Federal Energy Regulatory Commission and does not pose a significant danger to surrounding areas.

Located in Merrill, Wisconsin, this embankment dam is a vital component of the local water resource infrastructure, ensuring sustainable water management and energy production for the region. Despite being categorized as low hazard, the dam's risk assessment highlights the need for ongoing monitoring and management to address potential safety concerns. With a designated inspection frequency and emergency action plan in place, the Tomahawk Left Detached Embankment is well-equipped to handle any unforeseen events and safeguard the local community and environment.

As a prominent feature in the Detroit District, the Tomahawk Left Detached Embankment stands as a testament to effective dam engineering and management practices. With its primary purpose of hydroelectric power generation, this structure not only contributes to the region's energy needs but also provides recreational opportunities for residents and visitors. Maintaining a balance between functionality and safety, this dam serves as a valuable asset in the water resource and climate management landscape of Wisconsin.

Year Completed

1938

Dam Length

2050

Dam Height

20

River Or Stream

Wisconsin River

Primary Dam Type

Earth

Surface Area

2773

Hydraulic Height

10.5

Drainage Area

2028

Nid Storage

15180

Structural Height

27

Hazard Potential

Low

Foundations

Soil

Nid Height

27
       
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.