Grand Lake (Matagamon)

Penobscot River· Penobscot, Maine· Built 1941· Concrete· 25 ft tall
High Hazard Hydroelectric Other Private

Key Takeaway

Grand Lake (Matagamon) is classified as high hazard in Maine. It was completed in 1941 and is 85 years old. Its primary use is hydroelectric. High hazard means loss of life is likely if the dam fails — it does not indicate the dam's current condition. Learn more.

Physical Details

Dam Height 25 ft (taller than 83.1% in ME)
Dam Length218 ft
Dam TypeConcrete
Max Storage45.8K acre-ft
Normal Storage41.4K acre-ft
Surface Area4,200 acres
Drainage Area485 sq mi
Year Completed1941 (85 years old)
Year Modified1959
NID IDME00180

Safety Information

High Hazard

Loss of human life is likely if the dam fails.

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

Emergency Action Plan: Yes
Last Inspection: November 12, 2021
State Regulated: Yes
Regulatory Agency: MEMA

Ownership

Mattagamon Lake Association

Private

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Grand Lake (Matagamon)?

Grand Lake (Matagamon) is classified as High Hazard. Loss of human life is likely if the dam fails. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Grand Lake (Matagamon)?

Grand Lake (Matagamon) is owned by Mattagamon Lake Association (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Grand Lake (Matagamon) built?

Grand Lake (Matagamon) was completed in 1941, making it 85 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 Grand Lake (Matagamon)?

Grand Lake (Matagamon) serves the following purposes: Hydroelectric, Other. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Grand Lake (Matagamon)?

Grand Lake (Matagamon) has a dam height of 25 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 Grand Lake (Matagamon) last inspected?

Grand Lake (Matagamon) was last inspected on November 12, 2021. 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.