Deer Flat Middle Dike

About Deer Flat Middle Dike

The primary purpose of Deer Flat Middle Dike 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 near Nampa.

The dam stands 18 feet tall and stretches 1,262 feet across, creates a reservoir covering 10,100 acres, has a maximum storage capacity of 159,000 acre-feet, and collects water from a drainage area of 92 square miles. Completed in 1911, 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.

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.

Search for dams near your address to see all dams in your area with hazard classifications and safety data.