Central Reservoir Report

Last Updated: December 6, 2025

Central Dam, also known as Janesville Dam, is a hydroelectric structure located on the Rock River in Wisconsin.


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Summary

Built in 1927, this Timber Crib dam stands at a height of 8 feet and stretches 325 feet in length, providing critical water storage of 3,675 acre-feet and a surface area of 548 acres. The dam's primary purpose is hydroelectric power generation, with additional benefits for recreation.

Managed by the Federal Energy Regulatory Commission, the Central Dam has a controlled spillway with a width of 243 feet and is equipped with four slide (sluice) gates for water flow regulation. Despite its low hazard potential, the dam is rated as having a very high risk due to its age and condition assessment not being available. Emergency action plans have been prepared and updated periodically to ensure public safety and risk management measures are in place.

With its historical significance and vital role in water resource management and energy production, Central Dam serves as a notable structure in the region. Enthusiasts of water resources and climate will find interest in the dam's features, operational details, and the ongoing efforts to address potential risks associated with its continued use.

Year Completed

1927

Dam Length

325

Dam Height

8

River Or Stream

Rock River

Surface Area

548

Drainage Area

3205

Nid Storage

3675

Outlet Gates

Slide (sluice gate) - 4

Hazard Potential

Low

Nid Height

8
       
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.