Dull Knife

About Dull Knife

The primary purpose of Dull Knife is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by North Fork Powder River Water Users Assn (private). It impounds the North Fork Powder River near Arvada.

The dam stands 80 feet tall and stretches 570 feet across, creates a reservoir covering 130 acres, has a maximum storage capacity of 5,003 acre-feet, and collects water from a drainage area of 25 square miles. Completed in 1966, the structure is well into its service life at over 50 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 07/13/2022.

At 80 feet, this dam is taller than 97% of all dams in the United States.

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

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