East Boulder Tailings Dam

Sweet Grass, Montana·
High Hazard Tailings Private

Key Takeaway

East Boulder Tailings Dam is classified as high hazard in Montana. Its primary use is tailings. 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

Max Storage460 acre-ft
Normal Storage153 acre-ft
Surface Area103 acres
Drainage Area0 sq mi
NID IDMT03989

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: February 9, 2021
State Regulated: Yes
Regulatory Agency: DEQ

Ownership

STILLWATER MINING CO

Private

Frequently Asked Questions

What is the hazard classification of East Boulder Tailings Dam?

East Boulder Tailings Dam 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 East Boulder Tailings Dam?

East Boulder Tailings Dam is owned by STILLWATER MINING CO (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

What is the primary purpose of East Boulder Tailings Dam?

East Boulder Tailings Dam serves the following purposes: Tailings. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

When was East Boulder Tailings Dam last inspected?

East Boulder Tailings Dam was last inspected on February 9, 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.