North Topsail Water & Sewer Lagoon Dam

About North Topsail Water & Sewer Lagoon Dam

North Topsail Water & Sewer Lagoon Dam is a dam in Onslow, North Carolina. The dam is owned by Onslow Water And Sewer Authority (onwasa) (public utility). It impounds the Mill Creek near North Topsail Beach.

The dam stands 18 feet tall and stretches 1,000 feet across, creates a reservoir covering 10 acres, and has a maximum storage capacity of 180 acre-feet.

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 08/13/2024.

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

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