New Mill Pond Dam Reservoir Report

Last Updated: January 1, 2026

New Mill Pond Dam, located in Smithtown, Suffolk County, New York, is a local government-owned structure built in 1825 primarily for recreational purposes.


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Summary

The earth dam stands at a height of 15 feet and spans a length of 465 feet, with a storage capacity of 545 acre-feet. Situated along the Northeast Branch river, the dam has a spillway width of 18 feet and a surface area of 109 acres, serving as a popular spot for outdoor activities.

Despite being classified with a low hazard potential and not yet assessed for its condition, New Mill Pond Dam poses a moderate risk due to its age and lack of recent inspections. The dam is regulated by the New York State Department of Environmental Conservation and has been granted state permits for operation, inspection, and enforcement. The last inspection was conducted in October 2011, and while the Emergency Action Plan status is unspecified, the dam's risk management measures are not detailed.

Climate and water resource enthusiasts may be intrigued by the historical significance and structural characteristics of New Mill Pond Dam. With its picturesque location and potential for recreational use, the dam serves as a focal point for local activities while also raising concerns about its maintenance and risk management strategies. As a part of the larger water infrastructure in the area, the dam's condition and regulatory oversight offer valuable insights into the challenges of balancing conservation and public access in a changing climate landscape.

Year Completed

1825

Dam Length

465

Dam Height

15

River Or Stream

NORTHEAST BRANCH

Primary Dam Type

Earth

Surface Area

109

Drainage Area

23.02

Nid Storage

545

Hazard Potential

Low

Nid Height

15
       
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.