Isaak Dam No 4

About Isaak Dam No 4

The primary purpose of Isaak Dam No 4 is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Dugualla Bay Company Llc (private).

The dam stands 9 feet tall, has a maximum storage capacity of 64 acre-feet, and collects water from a drainage area of 150 square miles. Completed in 1987, the structure is 39 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. Notably, no emergency action plan is currently on file for this high-hazard dam. The most recent inspection on record was 05/10/2017. That was 8 years ago, which is on the longer end for a high-hazard structure.

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

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