Polson Sewage Lagoon

TR-FLATHEAD RIVER· Lake, Montana· Built 1963· Earth· 8 ft tall
Significant Hazard Other Local Government

Key Takeaway

Polson Sewage Lagoon is classified as significant hazard in Montana. It was completed in 1963 and is 63 years old. Its primary use is other. Significant hazard means failure could cause economic or environmental damage. Learn more.

Physical Details

Dam Height 8 ft (taller than 0.5% in MT)
Dam Length3,200 ft
Dam TypeEarth
Max Storage84 acre-ft
Normal Storage84 acre-ft
Year Completed1963 (63 years old)
NID IDMT01422

Safety Information

Significant Hazard

No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities.

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

CITY OF POLSON

Local Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Polson Sewage Lagoon?

Polson Sewage Lagoon is classified as Significant Hazard. No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Polson Sewage Lagoon?

Polson Sewage Lagoon is owned by CITY OF POLSON (Local Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Polson Sewage Lagoon built?

Polson Sewage Lagoon was completed in 1963, making it 63 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 Polson Sewage Lagoon?

Polson Sewage Lagoon 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 Polson Sewage Lagoon?

Polson Sewage Lagoon 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.

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.