Grand Lake St. Marys - East Embankment

About Grand Lake St. Marys - East Embankment

The primary purpose of Grand Lake St. Marys - East Embankment is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Odnr, Division Of Parks & Watercraft (state). It impounds the Outlet To Miami And Erie Canal Feeder near St. Marys.

The dam stands 18 feet tall and stretches 10,000 feet across, creates a reservoir covering 13,981 acres, has a storage capacity of 62,194 acre-feet, and collects water from a drainage area of 110 square miles. Completed in 1841, 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. An emergency action plan is in place for this dam. The most recent inspection on record was 11/20/2024.

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

Search for dams near your address to see all dams in your area with hazard classifications and safety data.