Cavendish Reservoir Report

Last Updated: December 15, 2025

Cavendish is a concrete gravity dam located on the Black River in Windsor, Vermont.


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Summary

Built in 1907, this hydroelectric dam stands at 46 feet tall and has a length of 230 feet. With a storage capacity of 130 acre-feet and a drainage area of 82 square miles, Cavendish serves as an essential source of renewable energy in the region.

Despite its age, Cavendish has a low hazard potential and is currently rated as "Not Rated" in terms of condition assessment. The dam has not undergone any modifications in recent years and last received an inspection in 1997. While it is not state-regulated or permitted, Cavendish continues to operate safely and effectively, providing a valuable contribution to the local energy grid.

As a public utility dam, Cavendish plays a crucial role in harnessing the power of the Black River for hydroelectric purposes. With its unique multi-arch design and rock foundation, this historic structure stands as a testament to Vermont's commitment to sustainable energy sources. For water resource and climate enthusiasts, Cavendish offers a fascinating glimpse into the intersection of technology, nature, and renewable energy production in the beautiful New England landscape.

Year Completed

1907

Dam Length

230

Dam Height

46

River Or Stream

BLACK RIVER

Primary Dam Type

Concrete

Surface Area

10

Hydraulic Height

46

Drainage Area

82

Nid Storage

130

Structural Height

46

Hazard Potential

Low

Foundations

Rock

Nid Height

46
       
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.