Simplot Effluent Irrigation Lagoon

About Simplot Effluent Irrigation Lagoon

The primary purpose of Simplot Effluent Irrigation Lagoon 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 Unnamed Streams Blackfoot River near Chubbuck.

The dam stands 39 feet tall and stretches 3,800 feet across, creates a reservoir covering 38 acres, has a storage capacity of 900 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1981, the structure is 45 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. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 09/26/2019.

At 39 feet, this dam is taller than 86% 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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