Kopp Reservoir Report

Last Updated: December 14, 2025

Kopp is a privately owned dam located on the TR-Little Eau Pleine River in Marathon, Wisconsin.


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Summary

Constructed in 1967, this Earth-type dam stands at a height of 15 feet and has a length of 1120 feet. With a maximum storage capacity of 50 acre-feet and a normal storage of 20 acre-feet, Kopp serves a primary purpose of "Other" with a low hazard potential and a moderate risk assessment.

Managed by the Wisconsin Department of Natural Resources (WIDNR), Kopp is state regulated, permitted, inspected, and enforced. Although the dam has not been rated for its condition assessment, it has a designated inspection frequency of 10 years with the last inspection date recorded in September 2010. Despite its low hazard potential, the dam does not have an Emergency Action Plan (EAP) in place, raising concerns for emergency preparedness in the event of a high-risk situation.

With its location in a rural area and a drainage area of 0.4 square miles, Kopp plays a crucial role in water resource management and flood control along the Little Eau Pleine River. As climate change impacts water resources, enthusiasts are encouraged to monitor the condition and risk assessment of dams like Kopp to ensure the safety and sustainability of our water infrastructure in a changing climate.

Year Completed

1967

Dam Length

1120

Dam Height

15

River Or Stream

TR-LITTLE EAU PLEINE RIVER

Primary Dam Type

Earth

Surface Area

7

Hydraulic Height

10

Drainage Area

0.4

Nid Storage

50

Structural Height

15

Hazard Potential

Low

Nid Height

15
       
Seasonal Comparison

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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.