Mill Brook Site 1 Dam Reservoir Report

Last Updated: December 6, 2025

Mill Brook Site 1 Dam, located in New Berlin, Chenango County, New York, stands as a vital structure managed by local government authorities with regulatory oversight from the NYS DEC.


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Summary

Built in 1979 by the USDA NRCS, this earth-type dam serves the primary purpose of flood risk reduction along the TR-UNADILLA RIVER. With a height of 52 feet and a length of 470 feet, the dam has a storage capacity of 395 acre-feet and a maximum discharge rate of 8850 cubic feet per second. Despite its high hazard potential, a recent inspection in July 2020 deemed its condition satisfactory.

The dam's spillway, measuring 115 feet in width, functions as an uncontrolled overflow mechanism to manage excess water levels during heavy rainfall events. The structure's normalized storage capacity is 3 acre-feet, serving a drainage area of 2.1 square miles. The dam's moderate risk rating reflects its current state of moderate vulnerability to failure, prompting continued monitoring and risk management measures. With a history of regulatory compliance and regular inspections, Mill Brook Site 1 Dam remains a crucial asset in safeguarding the surrounding community from potential flood-related disasters.

Year Completed

1979

Dam Length

470

Dam Height

52

River Or Stream

TR-UNADILLA RIVER

Primary Dam Type

Earth

Surface Area

1

Drainage Area

2.1

Nid Storage

395

Hazard Potential

High

Nid Height

52
       
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.