Blackstone River Dam Reservoir Report

Last Updated: December 11, 2025

The Blackstone River Dam, located in Grafton, Massachusetts, is a significant masonry structure that serves as a vital water supply source in the region.


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Summary

Owned privately, the dam is regulated by the Department of Conservation and Recreation, ensuring its compliance with state permitting, inspection, and enforcement requirements. With a height of 12 feet and a hydraulic height of 10 feet, the dam boasts a storage capacity of 77 acre-feet, providing essential water resources for the area.

Despite being classified as having a significant hazard potential, the Blackstone River Dam is assessed to be in fair condition as of its last inspection in May 2015. The dam's emergency action plan status and risk management measures are unspecified, but its risk assessment is rated as moderate. The structure overlooks the Blackstone River and plays a crucial role in maintaining the water supply for the community, highlighting its importance in mitigating the impacts of climate change and ensuring water resource sustainability.

With a drainage area of 92.5 square miles, the Blackstone River Dam is a key component of the region's water infrastructure. Its historical significance and role in water supply underscore the importance of its continued maintenance and regulation to address potential risks and ensure the safety and security of the surrounding area's water resources in the face of changing climatic conditions.

Dam Height

12

River Or Stream

BLACKSTONE RIVER

Primary Dam Type

Masonry

Hydraulic Height

10

Drainage Area

92.5

Nid Storage

77

Hazard Potential

Significant

Foundations

Unlisted/Unknown

Nid Height

12
       
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.