Sudbury Reservoir Dam Reservoir Report

Last Updated: December 17, 2025

The Sudbury Reservoir Dam, located in Southborough, Massachusetts, is a vital structure that serves as a key component in the state's water supply system.


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Summary

Completed in 1899, this concrete dam with a height of 77 feet and a hydraulic height of 70 feet, plays a crucial role in storing water from the Stony Brook, with a storage capacity of 33,020 acre-feet. The dam covers a surface area of 2.8 square miles and has a drainage area of 22.3 square miles, making it an essential resource for the region.

Managed by the Department of Conservation and Recreation, the Sudbury Reservoir Dam is regularly inspected, with a satisfactory condition assessment as of August 2016. With a high hazard potential and a moderate risk assessment, the dam's emergency action plan is continuously updated to ensure preparedness for any potential incidents. The dam meets state regulations for permitting, inspection, and enforcement, highlighting the commitment to maintaining its structural integrity and the safety of the surrounding community.

As a crucial water supply infrastructure in Worcester County, the Sudbury Reservoir Dam is not only a feat of engineering but also a testament to the state's dedication to water resource management and climate resilience. Its historical significance, combined with its modern-day regulatory compliance and risk management measures, make it a cornerstone in ensuring a sustainable water supply for the region's residents and ecosystems.

Year Completed

1899

Dam Length

2000

Dam Height

77

River Or Stream

STONY BROOK

Primary Dam Type

Concrete

Surface Area

2.8

Hydraulic Height

70

Drainage Area

22.3

Nid Storage

33020

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

77
       
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.