Upper Kohanza Lake Dam Reservoir Report

Last Updated: December 5, 2025

Upper Kohanza Lake Dam, nestled in Fairfield, Connecticut, is a crucial water supply structure owned and regulated by the local government.


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Summary

Standing at a height of 30 feet and stretching 650 feet in length, this Earth-type dam was completed back in 1866 to cater to the region's water needs by harnessing Kohanza Brook. With a storage capacity of 31 acre-feet and a significant hazard potential, the dam plays a vital role in maintaining water levels and supporting the surrounding ecosystem.

Despite its age, Upper Kohanza Lake Dam has stood the test of time, with a satisfactory condition assessment as of October 2020. This dam not only serves as a water supply source but also contributes to flood control measures in the area. With a drainage area of 0.43 square miles and a spillway width of 26 feet, the dam can handle a maximum discharge of 525 cubic feet per second, ensuring the safety and stability of the structure. Regular inspections and emergency preparedness are key aspects of its management, further highlighting the importance of this dam in the region's water resource and climate resilience efforts.

As climate change continues to impact water resources, the role of Upper Kohanza Lake Dam in ensuring water supply security and flood protection becomes even more vital. With a history dating back over a century, this dam stands as a testament to human ingenuity in managing and harnessing natural resources for the benefit of the community. As water resource and climate enthusiasts, understanding and appreciating the significance of structures like Upper Kohanza Lake Dam is crucial for fostering sustainable water management practices and building resilience in the face of changing environmental conditions.

Year Completed

1866

Dam Length

650

Dam Height

30

River Or Stream

KOHANZA BROOK

Primary Dam Type

Earth

Surface Area

29

Drainage Area

0.43

Nid Storage

31

Hazard Potential

Significant

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.