Middle Reservoir Dam Reservoir Report

Last Updated: December 5, 2025

Middle Reservoir Dam, located in Ansonia, Connecticut, is a historic masonry structure completed in 1890 for the primary purpose of water supply.


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Summary

Owned by a public utility, this dam stands at a height of 35 feet and has a length of 290 feet, with a storage capacity of 36 acre-feet. Situated on Beaver Brook in New Haven County, it is regulated by the Connecticut Department of Energy and Environmental Protection (DEEP), ensuring its compliance with state permitting, inspection, and enforcement requirements.

With a significant hazard potential but a satisfactory condition assessment as of November 2019, Middle Reservoir Dam plays a crucial role in water resource management in the region. Its maximum discharge capacity reaches 132 cubic feet per second, and it covers a surface area of 3 acres with a drainage area of 0.68 square miles. The dam is equipped with a spillway width of 29 feet, although no outlet gates are reported. Despite its age, the dam continues to serve as a vital infrastructure for water storage and distribution in the area.

As a key component of the local water supply system, Middle Reservoir Dam serves as a reminder of the importance of maintaining and monitoring aging infrastructure to ensure the safety and reliability of water resources in the face of changing climate conditions. Its historical significance, coupled with its functional role in managing water flow and storage, underscores the need for continued vigilance and investment in the upkeep of critical dams to mitigate risks and adapt to evolving climate challenges.

Year Completed

1890

Dam Length

290

Dam Height

35

River Or Stream

BEAVER BROOK

Primary Dam Type

Masonry

Surface Area

3

Drainage Area

0.68

Nid Storage

36

Hazard Potential

Significant

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.