Lefferts Grist Mill Dam

TR-HUNTINGTON HARBOR· Suffolk, New York· Built 1800· Earth· 8 ft tall
Low Hazard Recreation Private

Key Takeaway

Lefferts Grist Mill Dam is classified as low hazard in New York. It was completed in 1800 and is 226 years old. Its primary use is recreation.

Physical Details

Dam Height 8 ft (taller than 5.1% in NY)
Dam Length730 ft
Dam TypeEarth
Max Storage54 acre-ft
Normal Storage27 acre-ft
Surface Area15 acres
Max Discharge360 cfs
Year Completed1800 (226 years old)
NID IDNY01502

Safety Information

Low Hazard

No probable loss of human life and low economic/environmental losses expected.

Hazard potential describes downstream consequences of failure, not the dam's current condition. What does this mean?

Emergency Action Plan: No
Last Inspection: May 5, 2009
State Regulated: Yes
Regulatory Agency: NYS DEC

Ownership

NATURE CONSERVANCY INC

Private

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Lefferts Grist Mill Dam?

Lefferts Grist Mill Dam is classified as Low Hazard. No probable loss of human life and low economic/environmental losses expected. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Lefferts Grist Mill Dam?

Lefferts Grist Mill Dam is owned by NATURE CONSERVANCY INC (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Lefferts Grist Mill Dam built?

Lefferts Grist Mill Dam was completed in 1800, making it 226 years old. Many U.S. dams were built between the 1930s and 1970s during a period of major infrastructure investment.

What is the primary purpose of Lefferts Grist Mill Dam?

Lefferts Grist Mill Dam serves the following purposes: Recreation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Lefferts Grist Mill Dam?

Lefferts Grist Mill Dam has a dam height of 8 ft. Dam height is measured from the natural streambed at the downstream toe to the top of the dam, and may differ from the visible height.

When was Lefferts Grist Mill Dam last inspected?

Lefferts Grist Mill Dam was last inspected on May 5, 2009. Inspection dates indicate when a formal review occurred, not the results of that inspection.

Data from the National Inventory of Dams (NID) maintained by the US Army Corps of Engineers. Dam conditions may have changed since the last update. This site is not affiliated with USACE. Do not use for emergency planning — contact your local dam safety program.