Simmons Lower Reservoir

About Simmons Lower Reservoir

Simmons Lower Reservoir is a dam in Providence, Rhode Island. The dam is owned by Johnston, Town Of (local government). It impounds the Cedar Swamp Brook near Johnston.

The dam stands 12 feet tall and stretches 1,200 feet across, creates a reservoir covering 49 acres, has a maximum storage capacity of 317 acre-feet, and collects water from a drainage area of 4 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. Notably, no emergency action plan is currently on file for this high-hazard dam. The most recent inspection on record was 09/09/2010. That was 15 years ago — unusually long for a high-hazard dam, which typically requires more frequent inspections.

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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