After the ice melted, the resulting depression was filled with water forming the lake.

The Conneaut outlet flows into French Creek, making it part of the Mississippi River drainage.

A settler named Cornelius Van Horn was captured by Wyandots or their allies near what is today Meadville, Pennsylvania.

The Lake level was raised about 10 ft (3.0 m) in the 1820s to permit the construction of the Beaver and Erie Canal.

In the 1870s, canals were made obsolete by railroads, and the lake was returned to its natural elevation, though a dam remains for flood control.

The deep, cold waters of the lake allow it to stay frozen relatively late into the spring.

Streams were dammed, forming several reservoirs larger than Conneaut Lake throughout the area.