From 1938 to 1942, the State of South Carolina created Lake Moultrie, surrounded by thirty-two (32) miles of dams and dikes, with a hydroelectric plant and Pinopolis Lock at the outlet or Tailrace Canal near Moncks Corner. This new lake effectively replaced the Old Santee Canal and inundated all of it on the Cooper side of the summit except for the last three miles.

The Diversion Canal was built at the same time as the Pinopolis Lock, and it is about four miles south of SC45, connecting Lake Marion with Lake Moultrie. Both the lock and the canal are currently in operation.