Cosca Regional Park Dam

About Cosca Regional Park Dam

The primary purpose of Cosca Regional Park Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Mncppc-cosca Park (local government). It impounds the Butler Branch near Piscataway.

The dam stands 28 feet tall and stretches 515 feet across, creates a reservoir covering 11 acres, has a maximum storage capacity of 356 acre-feet, and collects water from a drainage area of 2 square miles. Completed in 1970, 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. Notably, no emergency action plan is currently on file for this high-hazard dam. The most recent inspection on record was 11/07/2024.

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

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