Gnirk Family Trust Reservoir Report

Last Updated: December 5, 2025

The Gnirk Family Trust in Mauston, Wisconsin, is a privately owned earth dam constructed in 1969 for the primary purpose of flood risk reduction along the TR Brewer Creek.


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Summary

With a structural height of 27 feet and a length of 310 feet, the dam has a storage capacity of 25 acre-feet and a drainage area of 0.2 square miles. Despite being classified as low hazard potential, the dam is regularly inspected by the Wisconsin Department of Natural Resources and has a fair condition assessment as of October 2019.

Located in Juneau County, the Gnirk Family Trust dam plays a crucial role in managing water resources and minimizing the risk of flooding in the surrounding area. With a low hazard potential and a moderate risk assessment rating of 3, the dam provides essential flood protection for the community. In the event of an emergency, the dam's emergency action plan and inundation maps ensure that appropriate measures are in place to safeguard lives and property.

Managed by the private owners, the Gnirk Family Trust dam continues to be a vital infrastructure for flood risk reduction in Wisconsin. With its uncontrolled spillway and a maximum discharge of 180 cubic feet per second, the dam serves as a key component of the local water resource management system. Despite its age, the dam's condition remains fair, and regular inspections and maintenance uphold its functionality and reliability in protecting the community from potential flooding events.

Year Completed

1969

Dam Length

310

Dam Height

27

River Or Stream

TR BREWER CREEK

Primary Dam Type

Earth

Surface Area

2

Hydraulic Height

20

Drainage Area

0.2

Nid Storage

25

Structural Height

27

Hazard Potential

Low

Nid Height

27
       
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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.