Oswego Lake Dam

TUALATIN RIVER (OFFSTREAM)· Clackamas, Oregon· Built 1921· Concrete· 32 ft tall
Significant Hazard Hydroelectric Recreation Private

Key Takeaway

Oswego Lake Dam is classified as significant hazard in Oregon. It was completed in 1921 and is 105 years old. Its primary use is hydroelectric. Significant hazard means failure could cause economic or environmental damage. Learn more.

Physical Details

Dam Height 32 ft (taller than 63.9% in OR)
Dam Length120 ft
Dam TypeConcrete
Max Storage7.0K acre-ft
Normal Storage9.8K acre-ft
Surface Area433 acres
Drainage Area6 sq mi
Max Discharge1,400 cfs
Year Completed1921 (105 years old)
NID IDOR00237

Safety Information

Significant Hazard

No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities.

Hazard potential describes downstream consequences of failure, not the dam's current condition. What does this mean?

Emergency Action Plan: No
Last Inspection: November 19, 2020
State Regulated: Yes
Regulatory Agency: OWRD

Ownership

LAKE OSWEGO CORPORATION

Private

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Frequently Asked Questions

What is the hazard classification of Oswego Lake Dam?

Oswego Lake Dam is classified as Significant Hazard. No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Oswego Lake Dam?

Oswego Lake Dam is owned by LAKE OSWEGO CORPORATION (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Oswego Lake Dam built?

Oswego Lake Dam was completed in 1921, making it 105 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 Oswego Lake Dam?

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

How tall is Oswego Lake Dam?

Oswego Lake Dam has a dam height of 32 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 Oswego Lake Dam last inspected?

Oswego Lake Dam was last inspected on November 19, 2020. 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.