Cottonville Reservoir Report

Last Updated: December 12, 2025

Located in Adams, Wisconsin, Cottonville is a gravity dam built in 1924 primarily for recreational purposes.


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Summary

With a height of 25 feet and a hydraulic height of 17 feet, the dam boasts a storage capacity of 2,650 acre-feet and covers a surface area of 204 acres. The dam's drainage area spans 71 square miles, with a maximum discharge capacity of 1,544 cubic feet per second.

Despite its fair condition assessment in 2020, Cottonville poses a high hazard potential, prompting inspections every 2 years to ensure public safety. The dam's spillway, controlled by a 20-foot wide mechanism, adds an extra layer of protection for the surrounding area. Managed by the Wisconsin Department of Natural Resources, Cottonville is subject to state regulations, permitting, inspections, and enforcement measures to maintain its structural integrity.

As a vital water resource in the region, Cottonville serves as a hub for outdoor activities and wildlife conservation. The dam's scenic surroundings, including Roche-A-Cri and Big Flats, attract visitors and contribute to the local economy. With its very high risk assessment rating, ongoing risk management measures are crucial to safeguarding the dam and its downstream community from potential hazards.

Year Completed

1924

Dam Length

150

Dam Height

25

Primary Dam Type

Gravity

Surface Area

204

Hydraulic Height

17

Drainage Area

71

Nid Storage

2650

Structural Height

25

Hazard Potential

High

Nid Height

25
       
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.