Rio Mount Dam

Tr-Stillaguamish River· Snohomish, Washington· Built 1979· Earth·
Low Hazard Recreation Private

Key Takeaway

Rio Mount Dam is classified as low hazard in Washington. It was completed in 1979 and is 47 years old. Its primary use is recreation.

Physical Details

Dam Length300 ft
Dam TypeEarth
Max Storage60 acre-ft
Normal Storage25 acre-ft
Surface Area25 acres
Drainage Area1 sq mi
Max Discharge80 cfs
Year Completed1979 (47 years old)
NID IDWA01328

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: Washington Dept of Ecology

Ownership

HoaHau

Private

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Rio Mount Dam?

Rio Mount Dam 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 Rio Mount Dam?

Rio Mount Dam is owned by HoaHau (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Rio Mount Dam built?

Rio Mount Dam was completed in 1979, making it 47 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 Rio Mount Dam?

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

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.