Thomson Dam No 10 Reservoir Report

Last Updated: December 5, 2025

Thomson Dam No 10, located in Carlton County, Minnesota, is a gravity dam constructed in 1907 for hydroelectric purposes on the St.


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Summary

Louis River. With a height of 11 feet and a length of 80 feet, this dam plays a crucial role in water resource management, providing a storage capacity of 4,352 acre-feet. It is regulated by the Minnesota Department of Natural Resources and the Federal Energy Regulatory Commission, ensuring its safe operation and compliance with state and federal regulations.

The dam, with a high hazard potential, is associated with 13 structures and serves both hydroelectric power generation and recreational purposes. Despite its age, the dam's condition assessment is currently unavailable, highlighting the need for ongoing monitoring and maintenance. The emergency action plan for the dam was last revised in 2009, and the risk assessment indicates a high risk level, emphasizing the importance of proactive risk management measures to ensure the safety of the surrounding community and environment.

Thomson Dam No 10's location in the St. Paul District's US Army Corps of Engineers jurisdiction underscores its significance as a key infrastructure for water resource management in the region. As a focal point for hydroelectric power generation and recreation, this dam serves as a critical component of the local ecosystem. Continuous inspections by federal and state agencies, along with adherence to safety guidelines and risk management measures, are essential to safeguarding the dam's integrity and minimizing potential hazards for downstream communities and the environment.

Year Completed

1907

Dam Length

80

Dam Height

11

River Or Stream

St Louis River

Surface Area

375

Hydraulic Height

11

Nid Storage

4352

Structural Height

11

Hazard Potential

High

Nid Height

11
       
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.