Collins Company Upper Pond Dam Reservoir Report

Last Updated: December 10, 2025

The Collins Company Upper Pond Dam, located in Unionville, Connecticut, is a historic masonry dam completed in 1837 on the Farmington River.


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Summary

With a height of 32 feet and a length of 660 feet, this dam serves primarily for recreation purposes, providing a surface area of 140 acres and a storage capacity of 1400 acre-feet. The dam has a significant hazard potential but is currently in satisfactory condition according to a 2015 assessment.

Despite not being state-regulated or permitted, the Collins Company Upper Pond Dam plays a crucial role in the local community, offering opportunities for recreation and enjoyment. With an uncontrolled spillway and a maximum discharge of 55,000 cubic feet per second, the dam presents a moderate risk level, prompting the need for an Emergency Action Plan (EAP) to ensure public safety in case of emergencies. Being a part of the rich history of the area, this dam stands as a testament to the engineering achievements of the past while serving as a reminder of the importance of proper maintenance and risk management in the face of changing climate conditions.

Year Completed

1837

Dam Length

660

Dam Height

32

River Or Stream

FARMINGTON RIVER

Primary Dam Type

Masonry

Surface Area

140

Drainage Area

359

Nid Storage

1400

Outlet Gates

Slide (sluice gate)

Hazard Potential

Significant

Nid Height

32
       
Seasonal Comparison

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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.