Foster Dam

About Foster Dam

The primary purpose of Foster Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Usace - Portland District (federal). It impounds the South Santiam River near Sweethome.

The dam stands 126 feet tall and stretches 4,800 feet across, creates a reservoir covering 1,220 acres, has a maximum storage capacity of 61,000 acre-feet, and collects water from a drainage area of 494 square miles. Completed in 1967, the structure is well into its service life at over 50 years old.

This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. An emergency action plan is in place for this dam. The most recent inspection on record was 06/10/2025.

At 126 feet, this dam is taller than 98% of all dams in the United States.

Living Downstream

If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Oregon dam safety program can provide more specific information about emergency planning for this structure.

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