Jefferson Marsh Wrp - South Reservoir Report

Last Updated: December 5, 2025

The Jefferson Marsh Wrp - South, located in Jefferson, Wisconsin, is a state-regulated water resource project along Deer Creek.


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Summary

Completed in 2004, this earth dam stands at a height of 8.7 feet and has a normal storage capacity of 500 acre-feet. With a low hazard potential and fair condition assessment, it is regularly inspected by the Wisconsin Department of Natural Resources (WIDNR) to ensure its safety and functionality.

Despite its low hazard potential, the Jefferson Marsh Wrp - South is crucial for managing water resources in the area, with a maximum discharge capacity of 604 cubic feet per second. This controlled spillway dam plays a significant role in flood control and water storage, helping to protect the surrounding area from potential risks. With a very high risk assessment rating of 1, it is important to have emergency action plans in place to address any potential issues and ensure the safety of the community.

Managed by the state of Wisconsin, the Jefferson Marsh Wrp - South is a vital infrastructure that contributes to the overall water management efforts in the region. With a focus on water resource management and climate resilience, this project showcases the importance of sustainable infrastructure development to address the challenges posed by changing environmental conditions.

Year Completed

2004

Dam Length

14880

Dam Height

8.7

River Or Stream

Deer Creek

Primary Dam Type

Earth

Surface Area

691

Hydraulic Height

6.7

Drainage Area

16.79

Nid Storage

1532

Structural Height

8.7

Hazard Potential

Low

Nid Height

9
       
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.
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Area Campgrounds