Phillips Mill Pond Dam Reservoir Report

Last Updated: January 1, 2026

Phillips Mill Pond Dam, located in Smithtown, New York, is a state-regulated structure on the Nissequogue River with a primary purpose of recreation.


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Summary

This earth-type dam, completed in 1850, stands at a height of 10 feet and stretches 500 feet in length. With a maximum storage capacity of 23 acre-feet, the dam serves as a recreational spot covering a surface area of 7 acres.

Despite its historical significance, the dam's condition assessment is poor, with a significant hazard potential. The last inspection in 2018 revealed maintenance issues, indicating a need for repair and reinforcement. With a moderate risk assessment rating of 3, there is a call for enhanced risk management measures to ensure the safety and stability of the dam for both recreational and environmental purposes.

Water resource and climate enthusiasts interested in the preservation and sustainability of dams like Phillips Mill Pond Dam should be aware of its current condition and the importance of regular inspections and maintenance to mitigate potential risks. As a vital structure on the Nissequogue River, efforts to improve its condition and reduce hazards can contribute to the overall health and resilience of the water ecosystem in the region.

Year Completed

1850

Dam Length

500

Dam Height

10

River Or Stream

NISSEQUOGUE RIVER

Primary Dam Type

Earth

Surface Area

7

Nid Storage

23

Hazard Potential

Significant

Nid Height

10
       
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.