South Norwalk Reservoir Dike Reservoir Report

Last Updated: December 5, 2025

The South Norwalk Reservoir Dike, also known as City Lake, is a vital water supply infrastructure located in Wilton, Connecticut.


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Summary

Built in 1899, this earth dam stands at a height of 20 feet and spans a length of 500 feet, with a storage capacity of 3,180 acre-feet. The reservoir serves as a key component in the local water supply system, with a normal storage capacity of 1,950 acre-feet and a surface area of 155 acres.

Managed by the Department of Energy and Environmental Protection (DEEP) in Connecticut, the South Norwalk Reservoir Dike is regulated, permitted, inspected, and enforced by state authorities. With a high hazard potential, the dam is classified as having a satisfactory condition assessment as of July 2015. The emergency action plan (EAP) for the dam was last revised in June 2019, ensuring that proper guidelines and measures are in place in case of any unforeseen incidents.

Located on Parting Brook and falling under the jurisdiction of the New England District of the US Army Corps of Engineers, the South Norwalk Reservoir Dike plays a crucial role in ensuring a reliable water supply for the region. With its historical significance and continued maintenance and oversight by state agencies, this dam serves as a critical infrastructure for water resource management and climate resilience efforts in Fairfield County, Connecticut.

Year Completed

1899

Dam Length

500

Dam Height

20

River Or Stream

PARTING BROOK

Primary Dam Type

Earth

Surface Area

155

Drainage Area

2.39

Nid Storage

3180

Hazard Potential

High

Nid Height

20
       
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.