Lake Harwinton Dam Reservoir Report

Last Updated: December 5, 2025

Lake Harwinton Dam, located in Harwinton, Connecticut, is a privately owned structure that serves primarily for recreational purposes.


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Summary

Built in 1930, this earth dam stands at a height of 30 feet and stretches 600 feet in length, creating a storage capacity of 230 acre-feet. The dam overlooks Catlin Brook and holds a normal storage capacity of 180 acre-feet, covering a surface area of 41 acres.

With a high hazard potential, the dam has been deemed to be in satisfactory condition as of the last assessment in July 2020. It is regulated by the Connecticut Department of Energy and Environmental Protection (DEEP) and undergoes regular inspections every two years. Despite its recreational focus, the dam's critical role in water resource management and flood protection cannot be overlooked, making it of interest to water resource and climate enthusiasts seeking to understand the complex interplay between infrastructure, nature, and human activity in safeguarding our waterways.

Year Completed

1930

Dam Length

600

Dam Height

30

River Or Stream

CATLIN BROOK

Primary Dam Type

Earth

Surface Area

41

Drainage Area

0.81

Nid Storage

230

Hazard Potential

High

Nid Height

30
       
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.