Oak Swamp Reservoir

About Oak Swamp Reservoir

The primary purpose of Oak Swamp Reservoir is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Johnston, Town Of (local government). It impounds the Dry Brook near Johnston.

The dam stands 20 feet tall and stretches 1,310 feet across, creates a reservoir covering 107 acres, has a maximum storage capacity of 720 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1865, the structure is one of the older dams in the region, with over a century and a half of service.

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 poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. Notably, no emergency action plan is currently on file for this high-hazard dam.

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

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