Colby Pond Reservoir Report

Last Updated: December 14, 2025

Colby Pond, located in Plymouth, Vermont, is a picturesque recreational spot with a dam that was completed in 1959.


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Summary

The dam, primarily made of earth and stone, stands at a height of 29 feet and has a length of 505 feet, creating a storage capacity of 210 acre-feet. The pond covers a surface area of 20 acres and is fed by the Twentymile Stream, offering a tranquil retreat for water resource and climate enthusiasts to enjoy.

Managed by the Vermont Department of Environmental Conservation, Colby Pond is regulated, permitted, inspected, and enforced by the state authorities to ensure its safety and compliance with regulations. Despite being classified as low hazard potential, the dam is assessed to be in fair condition as of the last inspection in May 2013. The pond's emergency action plan status, risk assessment, and inundation maps preparation are currently unspecified, indicating potential areas for improvement in emergency preparedness.

With its idyllic setting and recreational opportunities, Colby Pond serves as a valuable resource for the local community and visitors alike. As water resource and climate enthusiasts explore this serene location, there is an opportunity to appreciate the careful design and maintenance of the dam, ensuring the safety and sustainability of this beloved waterway in Windsor County, Vermont.

Year Completed

1959

Dam Length

505

Dam Height

29

River Or Stream

TWENTYMILE STREAM

Primary Dam Type

Earth

Surface Area

20

Hydraulic Height

29

Drainage Area

0.49

Nid Storage

210

Structural Height

29

Hazard Potential

Low

Foundations

Soil

Nid Height

29
       
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.