Knightville Dam Reservoir Report

Last Updated: December 13, 2025

Knightville Dam, also known as Dry Reservoir, is a rockfill dam located in Hampshire, Massachusetts, along the Westfield River.


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Summary

Completed in 1941 by the US Army Corps of Engineers, the dam stands at 150 feet in height and has a storage capacity of 64,000 acre-feet. Its primary purpose is flood risk reduction, with a spillway width of 400 feet and a maximum discharge capacity of 83,000 cubic feet per second. The dam poses a high hazard potential, with a moderate risk assessment due to the large population living downstream that could be affected by catastrophic flooding in the event of a dam failure.

Although the risk of a dam failure is deemed unlikely, potential scenarios include uncontrolled high-volume releases from the spillway during significant storm events. The downstream communities, including Knightville, Huntington, and Russell, could be at risk of flooding in such situations. While the USACE has measures in place to monitor and manage the risks associated with Knightville Dam, including an Emergency Action Plan, there is ongoing study and assessment to further understand and mitigate any potential hazards. It is crucial for water resource and climate enthusiasts to stay informed about the dam's operations and risk management efforts to ensure the safety of the surrounding communities.

Year Completed

1941

Dam Length

1200

Dam Height

150

River Or Stream

WESTFIELD RIVER

Primary Dam Type

Rockfill

Surface Area

1

Hydraulic Height

145

Drainage Area

162

Nid Storage

64000

Structural Height

150

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

150
       
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.