Merrill Reservoir Report

Last Updated: December 6, 2025

Located in Lincoln, Wisconsin, the Merrill Hydroelectric Dam stands as a testament to engineering excellence, with a design by L A De Guere and completion in 1913.


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Summary

This gravity dam on the Wisconsin River serves a dual purpose of hydroelectric power generation and recreation, with a height of 23 feet and a spillway width of 400 feet. The dam boasts a storage capacity of 605 acre-feet and a maximum discharge of 29,500 cubic feet per second, making it a significant contributor to the region's water resource management.

Managed by the Federal Energy Regulatory Commission, the Merrill Dam is a vital piece of infrastructure that ensures the safety and efficiency of water flow in the area. Despite its low hazard potential, the dam undergoes regular inspections to maintain its structural integrity and operational effectiveness. With a risk assessment rating of very high, the dam's risk management measures are continuously evaluated to mitigate any potential threats and ensure the safety of surrounding communities.

For water resource and climate enthusiasts, the Merrill Hydroelectric Dam serves as a fascinating example of sustainable energy production and water management. Its strategic location in Merrill, Wisconsin, provides not only electricity but also recreational opportunities, showcasing the harmonious coexistence of human development and environmental conservation. As a historic landmark with a rich legacy, the Merrill Dam continues to play a crucial role in shaping the region's water infrastructure and resilience to climate challenges.

Year Completed

1913

Dam Length

705

Dam Height

23

River Or Stream

Wisconsin River

Primary Dam Type

Gravity

Surface Area

373

Hydraulic Height

15

Drainage Area

2721

Nid Storage

605

Outlet Gates

Vertical Lift - 26

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

23
       
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.