Castle Rock Reservoir Report

Nearby: Hamm Schwahn

Last Updated: December 5, 2025

Castle Rock is a gravity dam located on the Wisconsin River in Wisconsin Dells, Wisconsin.


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Summary

Built in 1950 by HARZA ENGINEERING CO, this hydroelectric dam serves multiple purposes including flood risk reduction, hydroelectric power generation, and recreation. With a height of 34 feet and a hydraulic height of 38 feet, Castle Rock has a storage capacity of 175,000 acre-feet and a normal storage capacity of 136,000 acre-feet.

The dam has a spillway width of 480 feet and is classified as having a high hazard potential. Controlled by the Federal Energy Regulatory Commission, Castle Rock is not state-regulated but does require state permitting and enforcement. Despite its age, the dam's risk assessment is very high at level 1, indicating the need for ongoing monitoring and management measures to ensure its safety and functionality for the surrounding community.

Castle Rock's location in Adams County, Wisconsin, makes it a pivotal structure in managing the water resources of the region. With its significant storage capacity and role in hydroelectric power generation, the dam plays a crucial role in water management, flood control, and energy production in the area. As a popular recreational spot for locals and visitors alike, Castle Rock offers not only practical benefits but also serves as a scenic destination for water resource and climate enthusiasts to explore and appreciate the intersection of nature and infrastructure.

Year Completed

1950

Dam Length

18700

Dam Height

34

River Or Stream

Wisconsin River

Primary Dam Type

Gravity

Surface Area

16640

Hydraulic Height

38

Drainage Area

6845

Nid Storage

175000

Structural Height

36

Outlet Gates

Tainter (radial) - 18

Hazard Potential

High

Foundations

Soil

Nid Height

38
       
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.