Thebes Lake

SUN COULEE· Rosebud, Montana· Built 1913· Earth· 16 ft tall
Low Hazard Other Private

Key Takeaway

Thebes Lake is classified as low hazard in Montana. It was completed in 1913 and is 113 years old. Its primary use is other.

Physical Details

Dam Height 16 ft (taller than 31.7% in MT)
Dam Length1,100 ft
Dam TypeEarth
Max Storage94 acre-ft
Normal Storage40 acre-ft
Year Completed1913 (113 years old)
NID IDMT02424

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
State Regulated: Yes
Regulatory Agency: DNRC

Ownership

WILLIAM MAGELSSEN, ESTATE OF

Private

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Thebes Lake?

Thebes Lake 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 Thebes Lake?

Thebes Lake is owned by WILLIAM MAGELSSEN, ESTATE OF (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Thebes Lake built?

Thebes Lake was completed in 1913, making it 113 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 Thebes Lake?

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

How tall is Thebes Lake?

Thebes Lake has a dam height of 16 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.

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.