Stone Hill Reservoir Dam Reservoir Report

Last Updated: December 5, 2025

Stone Hill Reservoir Dam, located in Griswold, Connecticut, is a captivating concrete structure completed in 1894 with a height of 35 feet and a length of 470 feet.


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Summary

Situated on Reservoir Brook, this dam serves as a critical water resource for the area, providing a storage capacity of 1000 acre-feet and covering a surface area of 30 acres. The dam is state-regulated and inspected regularly by the Department of Energy and Environmental Protection, ensuring its satisfactory condition and significant hazard potential is managed effectively.

The Stone Hill Reservoir Dam features an uncontrolled spillway with a width of 16 feet and utilizes slide (sluice gate) outlet gates for water release. Despite its age, the dam remains structurally sound and continues to fulfill its primary purpose as a vital component of the local water infrastructure. With its moderate risk assessment rating, the dam is closely monitored for any potential issues, with emergency action plans in place to address any unforeseen events. Overall, Stone Hill Reservoir Dam stands as a testament to engineering excellence and serves as a key asset in managing water resources and climate impacts in the region.

For water resource and climate enthusiasts, Stone Hill Reservoir Dam offers a fascinating glimpse into the intersection of infrastructure, environmental regulation, and emergency preparedness. Its historical significance, coupled with its ongoing role in safeguarding the community against water-related hazards, makes it a noteworthy subject of study and admiration. As climate change continues to impact water resources worldwide, structures like the Stone Hill Reservoir Dam serve as critical pieces of the puzzle in ensuring sustainable water management practices for future generations.

Year Completed

1894

Dam Length

470

Dam Height

35

River Or Stream

RESERVOIR BROOK

Primary Dam Type

Concrete

Surface Area

30

Drainage Area

0.95

Nid Storage

1000

Outlet Gates

Slide (sluice gate)

Hazard Potential

Significant

Foundations

Unlisted/Unknown

Nid Height

35
       
Seasonal Comparison

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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.