Koa Dam No 1

Tr-Mill Creek· Lewis, Washington· Built 1965· Earth·
Low Hazard Recreation Private

Key Takeaway

Koa Dam No 1 is classified as low hazard in Washington. It was completed in 1965 and is 61 years old. Its primary use is recreation.

Physical Details

Dam Length330 ft
Dam TypeEarth
Max Storage67 acre-ft
Normal Storage50 acre-ft
Surface Area50 acres
Drainage Area1 sq mi
Max Discharge162 cfs
Year Completed1965 (61 years old)
NID IDWA00110

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

Mhc Ltra Inc

Private

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Koa Dam No 1?

Koa Dam No 1 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 Koa Dam No 1?

Koa Dam No 1 is owned by Mhc Ltra Inc (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Koa Dam No 1 built?

Koa Dam No 1 was completed in 1965, making it 61 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 Koa Dam No 1?

Koa Dam No 1 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.