Prairie Du Sac Reservoir Report

Last Updated: December 5, 2025

Prairie Du Sac, located in Sauk County, Wisconsin, is home to a historic hydroelectric dam on the Wisconsin River.


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Summary

Built in 1914 by MEAD & SEASTONE, this gravity dam stands at a height of 50 feet and has a hydraulic height of 38 feet. With a storage capacity of 193,200 acre-feet and a normal storage level of 119,950 acre-feet, the dam serves as a vital source of hydroelectric power in the region.

Managed by a public utility, Prairie Du Sac dam is regulated by the Federal Energy Regulatory Commission (FERC) and is used primarily for hydroelectric purposes. The dam has a controlled spillway with a width of 820 feet and is equipped with 41 Tainter (radial) outlet gates. With a high hazard potential and very high risk assessment rating, the dam plays a crucial role in water resource management and climate resilience efforts in the area.

Despite its age, Prairie Du Sac dam remains a key infrastructure asset, providing essential flood control, water storage, and renewable energy generation capabilities. As climate change continues to impact water resources, the dam's strategic location and design make it a critical component of the region's adaptive capacity and sustainable development goals, ensuring the resilience of local communities in the face of a changing climate.

Year Completed

1914

Dam Length

3247

Dam Height

25

River Or Stream

Wisconsin River

Primary Dam Type

Gravity

Surface Area

9000

Hydraulic Height

38

Drainage Area

9180

Nid Storage

193200

Structural Height

50

Outlet Gates

Tainter (radial) - 41

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

50
       
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.