Dells Reservoir Report

Last Updated: December 13, 2025

Dells, located in Eau Claire, Wisconsin, is a gravity dam on the Chippewa River with a primary purpose of hydroelectric power generation and recreation.


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Summary

Completed in 1907, this multi-arch dam stands at 51 feet tall with a hydraulic height of 43.1 feet and a structural height of 51 feet. With a dam length of 619 feet and a storage capacity of 12,100 acre-feet, Dells plays a crucial role in regulating water flow and providing renewable energy to the region.

Managed by the Federal Energy Regulatory Commission, Dells has a controlled spillway width of 396 feet and can discharge up to 170,000 cubic feet per second. Despite being classified as a low hazard potential structure, the risk assessment for Dells indicates a very high risk level (1). The emergency action plan for the dam was last revised in December 2019, and regular inspections are conducted to ensure its safe operation. Dells serves as a key asset in water resource management and climate resilience efforts in the region, showcasing the importance of sustainable hydroelectric infrastructure for both energy production and environmental conservation.

Year Completed

1907

Dam Length

619

Dam Height

40

River Or Stream

Chippewa River

Primary Dam Type

Gravity

Surface Area

1183

Hydraulic Height

43.1

Drainage Area

5752

Nid Storage

12100

Structural Height

51

Outlet Gates

Tainter (radial) - 13

Hazard Potential

Low

Foundations

Rock

Nid Height

51
       
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.