Black Rock Dam Reservoir Report

Last Updated: December 5, 2025

Black Rock Dam, also known as Black Rock Lake, is a federally owned structure located in Waterbury, Connecticut.


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Summary

Built in 1971 by the US Army Corps of Engineers, this rockfill dam stands at a height of 130 feet and has a storage capacity of 8,450 acre-feet. Its primary purpose is flood risk reduction along Branch Brook, with a spillway width of 140 feet to handle a maximum discharge of 33,500 cubic feet per second.

The dam's hazard potential is rated as high, prompting regular inspections and risk management measures by the USACE to ensure its structural integrity and mitigate potential flood risks. Emergency preparedness is a key focus, with an Emergency Action Plan in place and updated regularly to coordinate responses in case of a dam-related emergency. USACE works closely with local authorities and the public to raise awareness and ensure readiness for any unforeseen events.

Despite the risks associated with dam operations, USACE's diligent monitoring and maintenance practices aim to address all types of flood risks and maintain the dam's functionality. With a focus on public safety and proactive risk management, Black Rock Dam stands as a crucial infrastructure for flood protection in the region, requiring ongoing attention and preparedness to safeguard the surrounding communities and water resources.

Year Completed

1971

Dam Length

933

Dam Height

130

River Or Stream

BRANCH BROOK

Primary Dam Type

Rockfill

Surface Area

21

Hydraulic Height

125

Drainage Area

20

Nid Storage

8450

Structural Height

130

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

130
       
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.