Holyoke - Overflow No. 2 Reservoir Report

Last Updated: December 6, 2025

Holyoke - Overflow No.


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Summary

2 is a historic masonry dam located in Holyoke, Massachusetts, along the Holyoke Canal. Built in 1860, this dam serves a primary purpose of hydroelectric power generation, with additional benefits for recreation. With a height of 30 feet and a length of 105 feet, it has a storage capacity of 26,000 acre-feet and a maximum discharge rate of 2,615 cubic feet per second. The dam features a controlled spillway with a width of 105 feet, ensuring safe water release during high flow events.

Managed by the local government and regulated by the Federal Energy Regulatory Commission, Holyoke - Overflow No. 2 has a high hazard potential and a very high risk assessment rating. Although the condition assessment is currently not available, the dam undergoes inspections with a frequency of 1 year to ensure its safety and integrity. With emergency action plans in place and emergency contacts updated periodically, the dam is well-prepared to handle any unforeseen events and protect downstream communities in the event of a breach.

As a significant water resource structure in the region, Holyoke - Overflow No. 2 plays a crucial role in the local energy production and recreational activities. Its historical significance, combined with its modern regulatory oversight and risk management measures, make it a fascinating site for water resource and climate enthusiasts to study and appreciate.

Year Completed

1860

Dam Length

105

Dam Height

30

River Or Stream

Holyoke Canal

Primary Dam Type

Masonry

Surface Area

2290

Drainage Area

8309

Nid Storage

26000

Outlet Gates

Slide (sluice gate) - 4

Hazard Potential

High

Nid Height

30
       
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.