Thomson Dam No 5 Reservoir Report

Last Updated: December 5, 2025

Thomson Dam No 5, located in Carlton, Minnesota, is a significant hydroelectric structure built in 1907 with a primary purpose of generating electricity.


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Summary

This gravity dam stands at a height of 23 feet and has a storage capacity of 4,352 acre-feet, providing essential water resources for the surrounding area. The dam is situated on the St. Louis River and is under the regulatory oversight of the Federal Energy Regulatory Commission, ensuring its safe operation and inspection.

With a high hazard potential due to its location and structure, Thomson Dam No 5 is a crucial component of the region's water resource management. The dam also serves recreational purposes, offering a surface area of 375 acres for outdoor activities and enjoyment. Despite its age, the dam's condition assessment is not available, highlighting the need for ongoing monitoring and maintenance to ensure its reliability and safety for both the environment and communities downstream.

Thomson Dam No 5 is part of a network of associated structures and is subject to regular inspections to mitigate risks and manage emergency situations effectively. With its historical significance and essential role in water resource management and hydroelectric power generation, this dam serves as a testament to the ingenuity and engineering capabilities of its time, reflecting the ongoing importance of sustainable water management practices in the face of climate change and evolving environmental challenges.

Year Completed

1907

Dam Length

100

Dam Height

23

River Or Stream

St Louis River

Surface Area

375

Hydraulic Height

23

Nid Storage

4352

Structural Height

23

Hazard Potential

High

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.