Rhinelander Reservoir Report

Last Updated: December 7, 2025

Rhinelander, located in Oneida, Wisconsin, is home to a significant hydroelectric dam on the Wisconsin River.


°F

°F

mph

Wind

%

Humidity

Summary

Built in 1876, this gravity dam stands at 24 feet in height and stretches 511 feet in length, providing a storage capacity of 24,700 acre-feet. The dam serves as a crucial source of hydroelectric power, with a normal storage capacity of 21,500 acre-feet and a maximum discharge of 7,000 cubic feet per second.

With a spillway width of 57 feet and controlled spillway type, the dam has a high hazard potential and a very high risk assessment rating. Despite its age, the dam continues to operate under the jurisdiction of the Federal Energy Regulatory Commission, with state permitting and enforcement in place. The dam's emergency action plan was last revised in January 2021, highlighting its importance in ensuring public safety in the event of a crisis.

For water resource and climate enthusiasts, Rhinelander's hydroelectric dam offers a fascinating blend of history, engineering, and environmental impact. As a vital component of the region's energy infrastructure, this dam serves as a reminder of the intricate balance between harnessing natural resources for power generation and mitigating the potential risks associated with large-scale water management structures. Its presence on the Wisconsin River not only contributes to the local economy but also underscores the need for ongoing monitoring and maintenance to ensure the safety and sustainability of this essential resource.

Year Completed

1876

Dam Length

511

Dam Height

24

River Or Stream

Wisconsin River

Primary Dam Type

Gravity

Surface Area

3576

Hydraulic Height

24

Drainage Area

861

Nid Storage

24700

Structural Height

24

Outlet Gates

Other Controlled - 14, Tainter (radial) - 1, Vertical Lift - 2

Hazard Potential

High

Foundations

Soil

Nid Height

24
       
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.