Horn School Rest Area Sewage Lagoon

Offstream· Whitman, Washington· Built 1996· Earth·
High Hazard Other State Government

Key Takeaway

Horn School Rest Area Sewage Lagoon is classified as high hazard in Washington. It was completed in 1996 and is 30 years old. Its primary use is other. 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

Dam Length1,200 ft
Dam TypeEarth
Max Storage22 acre-ft
Normal Storage19 acre-ft
Surface Area3 acres
Drainage Area0 sq mi
Max Discharge10 cfs
Year Completed1996 (30 years old)
NID IDWA01766

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: July 18, 2023
State Regulated: Yes
Regulatory Agency: Washington Dept of Ecology

Ownership

WA DOT

State Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Horn School Rest Area Sewage Lagoon?

Horn School Rest Area Sewage Lagoon 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 Horn School Rest Area Sewage Lagoon?

Horn School Rest Area Sewage Lagoon is owned by WA DOT (State Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Horn School Rest Area Sewage Lagoon built?

Horn School Rest Area Sewage Lagoon was completed in 1996, making it 30 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 Horn School Rest Area Sewage Lagoon?

Horn School Rest Area 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.

When was Horn School Rest Area Sewage Lagoon last inspected?

Horn School Rest Area Sewage Lagoon was last inspected on July 18, 2023. 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.