Shongum Lake Dam

About Shongum Lake Dam

The primary purpose of Shongum Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Shongum Lake Property Owners Association (private). It impounds the Den Brook near Denville.

The dam stands 12 feet tall and stretches 200 feet across, creates a reservoir covering 66 acres, has a maximum storage capacity of 467 acre-feet, and collects water from a drainage area of 3 square miles. Completed in 1923, 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 satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 01/12/2024.

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

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