Deans Reservoir Dam Reservoir Report

Last Updated: December 6, 2025

Deans Reservoir Dam, located in Stonington, Connecticut, is a historic masonry dam completed in 1888 with a primary purpose of water supply.


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Summary

The dam stands at a height of 15 feet and has a storage capacity of 90 acre-feet, serving as a vital resource for the surrounding community. Situated on Copps Brook, the dam plays a crucial role in maintaining water levels and ensuring a stable water supply for residents in the area.

Owned by a public utility, Deans Reservoir Dam is regulated by the Department of Energy and Environmental Protection (DEEP) in Connecticut, with regular inspections and enforcement to ensure its safety and functionality. Despite being classified as having a high hazard potential, the dam is currently assessed to be in fair condition as of the last inspection in August 2020. With a spillway width of 24 feet and a surface area of 35 acres, the dam is equipped to manage water flow and mitigate potential risks.

As a key component of the water supply infrastructure in New London County, Deans Reservoir Dam serves as a critical resource for the region. With its rich history dating back over a century, the dam continues to play a vital role in water management and conservation efforts. Climate and water resource enthusiasts will find Deans Reservoir Dam to be a fascinating example of how historic structures can still contribute to modern-day water supply needs while adhering to stringent regulatory standards and safety measures.

Year Completed

1888

Dam Length

220

Dam Height

15

River Or Stream

COPPS BROOK

Primary Dam Type

Masonry

Surface Area

35

Drainage Area

5.3

Nid Storage

90

Hazard Potential

High

Nid Height

15
       
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.