Rainbow Lakes Dam

About Rainbow Lakes Dam

The primary purpose of Rainbow Lakes Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Township Of Parsippany-troy Hills (local government). It impounds the Whippany River near Mountain Lakes.

The dam stands 11 feet tall and stretches 200 feet across, creates a reservoir covering 16 acres, has a storage capacity of 265 acre-feet, and collects water from a drainage area of 0 square miles.

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 11/14/2024.

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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