Columbia Mill Dam Reservoir Report

Last Updated: December 7, 2025

Columbia Mill Dam, located in Lee, Massachusetts, is a concrete dam constructed in 1901 along the Housatonic River.


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Summary

The primary purpose of this dam is for water supply, with a storage capacity of 100 acre-feet and a drainage area of 184 square miles. The dam stands at a height of 25 feet and has a hydraulic height of 20 feet, making it a significant structure in the region.

Despite its historical significance, Columbia Mill Dam is currently in poor condition and has been assessed with a significant hazard potential. The dam is under state regulation by the Department of Conservation and Recreation, with regular inspections conducted to ensure safety and compliance. The spillway type is uncontrolled, with no outlet gates or associated structures, posing a moderate risk for potential incidents.

As water resource and climate enthusiasts, the unique design and historical background of Columbia Mill Dam along the Housatonic River make it an interesting structure to study. With its current condition and hazard potential, there is a need for ongoing risk management measures and maintenance to ensure the safety and integrity of this important water supply infrastructure in Massachusetts.

Year Completed

1901

Dam Length

116

Dam Height

25

River Or Stream

HOUSATONIC RIVER

Primary Dam Type

Concrete

Surface Area

0.01

Hydraulic Height

20

Drainage Area

184

Nid Storage

100

Hazard Potential

Significant

Foundations

Unlisted/Unknown

Nid Height

25
       
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.