Brooks And Ross Reservoir Report

Last Updated: December 6, 2025

Brooks and Ross is a local government-owned dam located in Marathon, Wisconsin, along the Eau Claire River.


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Summary

Completed in 1850, this gravity-type dam serves primarily for recreational purposes, offering a surface area of 184 acres and a drainage area of 404 acres. With a maximum discharge capacity of 12,300 cubic feet per second and a height of 12 feet, the dam provides a low hazard potential but is categorized as having a very high risk due to its age and condition assessment not being rated.

Despite its age, Brooks and Ross Dam remains state-regulated and maintained by the Wisconsin Department of Natural Resources (WIDNR), with regular inspections occurring every 10 years. The dam's normal storage capacity is 802 acre-feet, with a maximum storage of 1,200 acre-feet. The controlled spillway type and the dam's location within the St. Paul District of the US Army Corps of Engineers contribute to its structural integrity. The dam's emergency action plan was last revised in 2013, and it meets the necessary guidelines for risk management, although there are no inundation maps prepared for potential flooding scenarios. Overall, Brooks and Ross Dam presents an intriguing case study for water resource and climate enthusiasts interested in the conservation and management of aging infrastructure in the face of increasing environmental challenges.

Years Modified

1939 - Other

Year Completed

1850

Dam Length

500

Dam Height

12

River Or Stream

EAU CLAIRE

Primary Dam Type

Gravity

Surface Area

184

Hydraulic Height

6

Drainage Area

404

Nid Storage

1200

Structural Height

12

Hazard Potential

Low

Nid Height

12
       
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.