Great Stone

Merrimack River· Essex, Massachusetts· Built 1848· Masonry· 38 ft tall
Low Hazard Hydroelectric Recreation Private

Key Takeaway

Great Stone is classified as low hazard in Massachusetts. It was completed in 1848 and is 178 years old. Its primary use is hydroelectric.

Physical Details

Dam Height 38 ft (taller than 91.8% in MA)
Dam Length943 ft
Dam TypeMasonry
Max Storage19.9K acre-ft
Normal Storage19.9K acre-ft
Surface Area655 acres
Drainage Area4,660 sq mi
Max Discharge128,000 cfs
Year Completed1848 (178 years old)
NID IDMA00234

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: June 15, 2022
State Regulated: No

Ownership

Lawrence Hydroelectric Associates

Private

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Great Stone?

Great Stone 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 Great Stone?

Great Stone is owned by Lawrence Hydroelectric Associates (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Great Stone built?

Great Stone was completed in 1848, making it 178 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 Great Stone?

Great Stone serves the following purposes: Hydroelectric, Recreation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Great Stone?

Great Stone has a dam height of 38 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 Great Stone last inspected?

Great Stone was last inspected on June 15, 2022. 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.