Eureka Reservoir Report

Last Updated: December 5, 2025

Eureka is a gravity dam located on the Fox River in Winnebago, Wisconsin, completed in 1920 with a height of 8 feet and a length of 209 feet.


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Summary

The dam serves multiple purposes, including flood control and water storage, with a maximum storage capacity of 124 acre-feet and a normal storage of 33 acre-feet. The drainage area for the dam is 1492 square miles, with a maximum discharge capacity of 4560 cubic feet per second.

The dam is owned and regulated by the Wisconsin Department of Natural Resources (WIDNR), with state permitting, inspection, and enforcement in place. It has a low hazard potential and is currently in fair condition, assessed in May 2020. While the dam has an uncontrolled spillway and no locks, it has an inspection frequency of 10 years and is located within the jurisdiction of the state of Wisconsin.

Overall, Eureka Dam plays a crucial role in water resource management and flood prevention in the region. Its moderate risk assessment suggests the need for continued monitoring and management measures to ensure its safety and efficiency in the face of changing climate conditions and water resource demands.

Year Completed

1920

Dam Length

209

Dam Height

8

River Or Stream

FOX R.

Primary Dam Type

Gravity

Surface Area

24

Length Of Locks

149

Hydraulic Height

3

Drainage Area

1492

Nid Storage

124

Structural Height

8

Hazard Potential

Low

Nid Height

8
       
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.