South Norwalk Reservoir Dam Reservoir Report

Last Updated: December 5, 2025

The South Norwalk Reservoir Dam, also known as City Lake, is a vital infrastructure in Fairfield, Connecticut, serving as a key element in the public utility's water supply system.


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Summary

Completed in 1899, this earth dam stands at 36 feet high and stretches 870 feet in length, with a storage capacity of 3,180 acre-feet. Situated on the Belden Hill Brook, the dam plays a crucial role in regulating water flow and ensuring a stable water supply for the surrounding area.

Managed by the Department of Energy and Environmental Protection (DEEP) in Connecticut, the South Norwalk Reservoir Dam has a high hazard potential but is currently assessed to be in satisfactory condition. With a spillway width of 49 feet and an outlet gate system in place, the dam is equipped to handle a maximum discharge of 2,700 cubic feet per second. Regular inspections are conducted, with the last assessment taking place in July 2017, ensuring that the dam meets safety standards and remains a reliable source of water for the community.

As a significant piece of infrastructure in the region, the South Norwalk Reservoir Dam plays a crucial role in water resource management and climate resilience efforts. With its historical significance and ongoing maintenance, the dam continues to fulfill its primary purpose of providing a reliable water supply to the residents of Silvermine and the surrounding areas in Fairfield County.

Year Completed

1899

Dam Length

870

Dam Height

36

River Or Stream

BELDEN HILL BROOK

Primary Dam Type

Earth

Surface Area

155

Drainage Area

2.72

Nid Storage

3180

Outlet Gates

Slide (sluice gate)

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

36
       
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.