Grand Lake St. Marys State Park

Grand Lake St. Marys State Park is a state park with a large artificial water basin in Auglaize County, Ohio. The area covers roughly 590 acres of land and 13,500 acres of water, offering several swimming beaches, camping zones, and boat ramps along the shore.

The water reservoir was created in 1837 to supply the Miami-Erie Canal with additional water. After the canal system declined, the area was officially turned into an Ohio state park in 1949.

The artificial lake once fed locks along the Miami-Erie Canal, showing an early attempt to connect rivers and lakes for moving goods. Today anglers and boaters cross the wide water surface, its shape still recalling the original engineering purpose.

The campground includes 216 sites, with 154 offering electrical hookups, plus modern restrooms and showers. The on-site shop rents equipment for outdoor activities.

In 1891, drilling for oil began directly in the shallow water, with numerous derricks erected on the lake. These early offshore operations are considered forerunners of modern oil extraction techniques in water bodies.

Location: Auglaize County

Inception: 1949

Website: https://ohiodnr.gov/go-and-do/plan-a-visit/find-a-property/grand-lake-st-marys-state-park

GPS coordinates: 40.53116,-84.49968

Latest update: December 5, 2025 22:25