Hudson Bay Reservoir Report

Last Updated: December 5, 2025

Hudson Bay, also known as Moquah Lake, is a gravity dam located in Ashland, Wisconsin, along the Brunsweiler River.


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Summary

Constructed in 1969, this dam serves primarily for recreation purposes, with a maximum storage capacity of 672 acre-feet and a normal storage of 560 acre-feet. The dam has a structural height of 7.7 feet and a hydraulic height of 5 feet, with a length of 56 feet and a surface area of 240 acres.

Managed by the Wisconsin Department of Natural Resources (WIDNR), Hudson Bay is regulated, inspected, and enforced by the state agency to ensure safety and compliance with regulatory standards. Despite being classified as having a low hazard potential, the dam's risk assessment is rated as very high, indicating the importance of risk management measures. The last inspection of the dam was conducted in May 2011, with an inspection frequency of 10 years.

Overall, Hudson Bay offers a picturesque recreational setting for water resource and climate enthusiasts to enjoy and appreciate the beauty of Wisconsin's natural landscapes. With its tranquil waters and surrounding natural environment, the dam provides an opportunity for outdoor activities and wildlife observation, making it a valuable resource for both locals and visitors alike. As efforts continue to monitor and maintain the dam's safety, Hudson Bay remains a vital asset for the community's recreational and environmental well-being.

Year Completed

1969

Dam Length

56

Dam Height

7.7

River Or Stream

BRUNSWEILER RIVER

Primary Dam Type

Gravity

Surface Area

240

Hydraulic Height

5

Drainage Area

19

Nid Storage

672

Structural Height

7.7

Hazard Potential

Low

Nid Height

8
       
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.