Pattison State Park Reservoir Report

Last Updated: December 5, 2025

Pattison State Park in Wisconsin is a stunning natural oasis boasting the majestic Black River running through it.


°F

°F

mph

Wind

%

Humidity

Summary

The park is home to a gravity dam completed in 1931, standing at a height of 20 feet and spanning 300 feet in length. The dam serves primarily for recreation purposes, providing a surface area of 27 acres and a normal storage capacity of 180 acre-feet. With a significant hazard potential due to its very high risk assessment rating, the dam is inspected every three years to ensure its fair condition and safety.

Visitors to Pattison State Park can marvel at the breathtaking scenery while enjoying recreational activities such as hiking, camping, and picnicking. The controlled spillway with a width of 50 feet adds to the park's allure, offering a unique sight for water resource enthusiasts. The park's location in Douglas County, Wisconsin, makes it an ideal destination for those looking to immerse themselves in nature and appreciate the beauty of the Black River.

For climate and water resource enthusiasts, Pattison State Park is not only a haven for outdoor recreation but also a fascinating site to explore the engineering and management of a gravity dam. As the park is regulated and inspected by the Wisconsin Department of Natural Resources, visitors can learn about the importance of maintaining dam safety and the measures in place to mitigate risks. With its rich history and stunning natural features, Pattison State Park is a must-visit destination for those interested in water resources and climate conservation.

Year Completed

1931

Dam Length

300

Dam Height

20

River Or Stream

Black River

Primary Dam Type

Gravity

Surface Area

27

Hydraulic Height

13

Drainage Area

78

Nid Storage

340

Structural Height

20

Hazard Potential

Significant

Nid Height

20
       
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.