Stony Brook Reservoir Dam Reservoir Report

Last Updated: December 19, 2025

Stony Brook Reservoir Dam, located in Waltham, Massachusetts, is a crucial structure owned by the local government and regulated by the Department of Conservation and Recreation.


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Summary

Built in 1887 for water supply purposes, this earth dam stands at 32 feet high with a hydraulic height of 25.7 feet. With a storage capacity of 1,810 acre-feet and a surface area of 72 acres, the dam plays a vital role in managing the water resources in the region.

Despite its age, the dam is in satisfactory condition as of the last assessment in August 2016, with a high hazard potential due to its location on the Stony Brook river. The dam has an uncontrolled spillway type and a moderate risk assessment score of 3. Regular inspections are conducted every two years to ensure its safety and integrity. The dam's primary purpose of water supply underscores its importance in providing a reliable source of water to the surrounding area.

Stony Brook Reservoir Dam serves as a testament to the engineering ingenuity of the late 19th century and continues to be a critical infrastructure for water resource management in Middlesex County, Massachusetts. With its historical significance and functional importance, the dam stands as a reminder of the intersection between human innovation and environmental stewardship in sustaining water supplies and managing climate-related challenges.

Year Completed

1887

Dam Length

1200

Dam Height

32

River Or Stream

STONY BROOK

Primary Dam Type

Earth

Surface Area

72

Hydraulic Height

25.7

Drainage Area

24.4

Nid Storage

1810

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

32
       
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.