Deer Flat Lower Dam

About Deer Flat Lower Dam

The primary purpose of Deer Flat Lower Dam is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Bureau Of Reclamation (federal). It impounds the Boise River Snake River Os near Parma, Wilder.

The dam stands 49 feet tall and stretches 7,270 feet across, creates a reservoir covering 10,100 acres, has a maximum storage capacity of 159,365 acre-feet, and collects water from a drainage area of 80 square miles. Completed in 1908, the structure is over a century 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 06/28/2023.

At 49 feet, this dam is taller than 92% of dams nationwide.

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 Idaho dam safety program can provide more specific information about emergency planning for this structure.

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