Dundee Reservoir Report

Last Updated: December 5, 2025

Dundee, also known as Long Lake, is a picturesque water resource located in Fond du Lac, Wisconsin.


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Summary

Managed by the local government, this dam was completed in 1857 with a primary purpose of recreation. The earth dam stands at 8 feet tall and spans 280 feet in length, creating a surface area of 427 acres and a normal storage capacity of 2000 acre-feet.

With a drainage area of 24.5 square miles and a max discharge of 500 cubic feet per second, Dundee poses a significant hazard potential but is currently assessed to be in fair condition. The dam is regulated by the Wisconsin Department of Natural Resources and undergoes regular inspections, with the last assessment conducted in May 2020. The risk assessment for Dundee is moderate, and emergency preparedness plans are in place to ensure public safety in the event of an emergency.

For water resource and climate enthusiasts, Dundee offers a fascinating opportunity to explore the intersection of human infrastructure and natural landscapes. With its rich history dating back over a century, this recreational dam on the East Branch Milwaukee River serves as a vital water source while providing a serene backdrop for outdoor activities. As climate change continues to impact water resources, understanding the management and maintenance of structures like Dundee becomes increasingly essential for sustainable water management practices.

Years Modified

1944 - Other

Year Completed

1857

Dam Length

280

Dam Height

8

River Or Stream

EAST BRANCH MILWAUKEE

Primary Dam Type

Earth

Surface Area

427

Hydraulic Height

5

Drainage Area

24.5

Nid Storage

3200

Structural Height

8

Hazard Potential

Significant

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.