Rock Falls Reservoir Report

Last Updated: December 13, 2025

Rock Falls is a gravity dam located in Dunn, Wisconsin, along the Rock Creek.


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Summary

Built in 1864, this historic structure stands at 43 feet tall and spans 80 feet in length, with a storage capacity of 80 acre-feet. The dam is regulated by the Wisconsin Department of Natural Resources (WIDNR) and undergoes regular inspections to ensure its safety and functionality. Despite its age, the dam continues to hold a vital role in water resource management in the region, with a maximum discharge capacity of 4,990 cubic feet per second.

The condition assessment of Rock Falls dam is rated as "poor" with a high hazard potential, prompting the need for risk management measures to mitigate any potential threats. The dam's emergency action plan (EAP) status and inundation maps are currently under review, highlighting the importance of preparedness in the face of emergencies. With a moderate risk level assigned, stakeholders and authorities are actively working towards ensuring the safety and efficiency of this crucial infrastructure for the surrounding communities. For water resource and climate enthusiasts, Rock Falls serves as a reminder of the intricate balance between man-made structures and natural ecosystems in the face of changing environmental conditions.

Years Modified

1923 - Other

Year Completed

1864

Dam Length

80

Dam Height

43

River Or Stream

Rock Creek

Primary Dam Type

Gravity

Surface Area

9

Hydraulic Height

37

Drainage Area

32

Nid Storage

80

Structural Height

43

Hazard Potential

High

Nid Height

43
       
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.