Hansons Reservoir Report

Last Updated: December 21, 2025

Hansons, also known as Marsh-Miller, is a privately owned dam located in Eagleton, Wisconsin, along the O'Neil Creek.


°F

°F

mph

Wind

%

Humidity

Summary

This gravity dam was completed in 1870 and primarily serves as a recreational site, offering opportunities for activities such as boating and fishing. With a height of 16 feet and a storage capacity of 4,000 acre-feet, Hansons dam covers a surface area of 436 acres and has a drainage area of 16 square miles.

Despite its age, Hansons dam has a low hazard potential and is considered to be in fair condition, with its last inspection conducted in August 2014. The dam has undergone modifications in 1949 and 2004, enhancing its overall safety and functionality. With a moderate risk assessment rating of 3, the dam is regulated and inspected by the Wisconsin Department of Natural Resources, ensuring its compliance with state permitting, inspection, and enforcement requirements.

For water resource and climate enthusiasts, Hansons dam presents a fascinating blend of historical significance and modern recreational utility. Its picturesque location, combined with its structural integrity and regulatory oversight, makes it a noteworthy example of responsible dam management in the state of Wisconsin. As a key feature along the O'Neil Creek, Hansons dam continues to provide both recreational enjoyment and essential water management functions for the surrounding area.

Years Modified

1949 - Other, 2004 - Other

Year Completed

1870

Dam Length

250

Dam Height

16

River Or Stream

O'Neil Creek

Primary Dam Type

Gravity

Surface Area

436

Hydraulic Height

12

Drainage Area

16

Nid Storage

4000

Structural Height

16

Hazard Potential

Low

Nid Height

16
       
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.