North Lake Dam Reservoir Report

Last Updated: December 5, 2025

North Lake Dam, located in North Castle, New York, is a private concrete structure completed in 1936 with a primary purpose of recreation.


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Summary

Standing at a height of 32 feet and spanning 600 feet in length, this dam holds a maximum storage capacity of 249 acre-feet and normal storage of 210 acre-feet. The dam, situated on the Mianus River, has a surface area of 19 acres and a drainage area of 0.26 square miles.

Despite its satisfactory condition assessment, North Lake Dam poses a high hazard potential due to its location and design. The dam lacks a spillway and has a maximum discharge capacity of 70 cubic feet per second. In the event of a failure, the surrounding area could face significant inundation, highlighting the importance of regular inspections and maintenance. The last inspection in April 2019 revealed the dam to be in satisfactory condition, but its high-risk designation underscores the need for continued monitoring and risk management measures.

With its captivating setting on the Mianus River and crucial role in providing recreational opportunities, North Lake Dam serves as a vital water resource in Westchester County, New York. The dam's high risk potential necessitates ongoing attention to ensure the safety of surrounding communities and the preservation of its recreational value. As climate change impacts water resources, the management and maintenance of structures like North Lake Dam become increasingly important in safeguarding against potential hazards and ensuring sustainable water management practices for the future.

Year Completed

1936

Dam Length

600

Dam Height

32

River Or Stream

MIANUS RIVER

Primary Dam Type

Concrete

Surface Area

19

Drainage Area

0.26

Nid Storage

249

Hazard Potential

High

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.