Glen Hills 6 Reservoir Report

Last Updated: December 6, 2025

Located in Glenwood City, Wisconsin, Glen Hills 6 is a flood risk reduction dam designed by USDA NRCS and completed in 1975.


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Summary

With a height of 29.6 feet and a hydraulic height of 21 feet, this earth dam spans 635 feet and has a storage capacity of 191 acre-feet. Situated on a tributary to Tiffany Creek, this structure is regulated by the Wisconsin Department of Natural Resources and undergoes regular inspections to ensure its satisfactory condition.

Despite its high hazard potential, Glen Hills 6 is deemed to have a moderate risk level, with a satisfactory condition assessment as of February 2019. The dam has an uncontrolled spillway type and a maximum discharge capacity of 2095 cubic feet per second. While the dam does not have a designated emergency action plan, its last inspection in May 2020 revealed no major concerns, indicating a commitment to the safety and maintenance of this flood control structure. For water resource and climate enthusiasts, Glen Hills 6 serves as a noteworthy example of infrastructure designed to mitigate flooding in the St. Croix County area.

Year Completed

1975

Dam Length

635

Dam Height

29.6

River Or Stream

Tributary to Tiffany Creek

Primary Dam Type

Earth

Hydraulic Height

21

Drainage Area

1.08

Nid Storage

191

Structural Height

29.6

Hazard Potential

High

Nid Height

30
       
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.