Three Mile Falls Diversion

UMATILLA RIVER· Umatilla, Oregon· Built 1913· Concrete· 28 ft tall
Low Hazard Irrigation Federal Government

Key Takeaway

Three Mile Falls Diversion is classified as low hazard in Oregon. It was completed in 1913 and is 113 years old. Its primary use is irrigation.

Physical Details

Dam Height 28 ft (taller than 54.8% in OR)
Dam Length915 ft
Dam TypeConcrete
Max Storage300 acre-ft
Normal Storage300 acre-ft
Surface Area35 acres
Drainage Area1,280 sq mi
Max Discharge38,000 cfs
Year Completed1913 (113 years old)
NID IDOR00588

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
Last Inspection: June 25, 2002
State Regulated: No

Ownership

RECLAMATION

Federal Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Three Mile Falls Diversion?

Three Mile Falls Diversion 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 Three Mile Falls Diversion?

Three Mile Falls Diversion is owned by RECLAMATION (Federal Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Three Mile Falls Diversion built?

Three Mile Falls Diversion was completed in 1913, making it 113 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 Three Mile Falls Diversion?

Three Mile Falls Diversion serves the following purposes: Irrigation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Three Mile Falls Diversion?

Three Mile Falls Diversion has a dam height of 28 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.

When was Three Mile Falls Diversion last inspected?

Three Mile Falls Diversion was last inspected on June 25, 2002. 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.