Paper Mill Reservoir Report

Last Updated: December 15, 2025

Paper Mill, also known as Perch Lake in Sparta, Wisconsin, is a gravity dam built in 1865 with a primary purpose of recreation.


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Summary

Situated on the La Crosse River in Monroe County, this dam stands at a height of 14 feet and has a structural length of 910 feet. With a storage capacity of 382 acre-feet and a drainage area of 143 square miles, Paper Mill provides not only recreational opportunities but also contributes to flood control and water management in the region.

Despite being classified as low hazard potential with fair condition assessment, Paper Mill poses a very high risk due to its age and years of modification since 1925. The dam is under state jurisdiction and regulated by the Wisconsin Department of Natural Resources, with regular inspections and enforcement. The last inspection in September 2014 revealed no significant issues, but ongoing risk assessment and management measures are necessary to ensure the safety and integrity of this historic structure.

With its controlled spillway and historical significance, Paper Mill serves as a valuable asset for the community and the environment. As water resource and climate enthusiasts, it is essential to stay informed about the condition and management of such dams to protect both human life and natural ecosystems. Continued monitoring and maintenance of Paper Mill will help sustain its functions for future generations to enjoy and appreciate.

Years Modified

1925 - Other

Year Completed

1865

Dam Length

910

Dam Height

14

River Or Stream

LA CROSSE RIVER

Primary Dam Type

Gravity

Surface Area

33

Hydraulic Height

8

Drainage Area

143

Nid Storage

382

Structural Height

14

Hazard Potential

Low

Nid Height

14
       
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.