Saint John

About Saint John

The primary purpose of Saint John is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is private-owned. It impounds the Birch Creek Malad River near St Johns.

The dam stands 43 feet tall and stretches 680 feet across, creates a reservoir covering 41 acres, has a storage capacity of 630 acre-feet, and collects water from a drainage area of 10 square miles. Completed in 1918, 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. Its condition is rated unsatisfactory, indicating serious safety deficiencies exist that require immediate attention or remedial action. Notably, no emergency action plan is currently on file for this high-hazard dam. The most recent inspection on record was 04/23/2019.

At 43 feet, this dam is taller than 89% 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.

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