Lake Of Isles Reservoir Report

Last Updated: December 6, 2025

Lake of Isles, also known as Upper Slater Falls #1, is a private recreational lake located in North Stonington, Connecticut.


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Summary

The dam, completed in 1920, is an earth structure standing at 15 feet tall and spanning 160 feet in length. With a normal storage capacity of 609 acre-feet and a surface area of 92 acres, the lake provides ample opportunities for water-based activities and enjoyment.

Managed by the Connecticut Department of Energy and Environmental Protection (DEEP), the dam is regulated and inspected regularly to ensure its safety and compliance. With a significant hazard potential, it is crucial for emergency preparedness and risk management measures to be in place. Despite not being rated for its current condition, the dam's last inspection in July 2016 highlighted the importance of continued monitoring and maintenance to uphold its structural integrity and public safety.

Surrounded by the natural beauty of New London County, Lake of Isles serves as a vital water resource for the local community and offers a tranquil escape for outdoor enthusiasts. With its picturesque setting and recreational allure, the lake remains a cherished destination for those seeking a peaceful retreat amidst the changing climate and environmental challenges of today.

Year Completed

1920

Dam Length

160

Dam Height

15

River Or Stream

Lake of Isles Brook

Primary Dam Type

Earth

Surface Area

92

Drainage Area

0.68

Nid Storage

609

Structural Height

15

Hazard Potential

Significant

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.