The Saint George River empties into Thomaston, Harbor in Thomaston, located about four miles southwest of Rockland and 11 miles northeast of Muscongus Bay. Both the harbor and river are used by recreational boaters, windjammer cruise vessels, and boat construction firms. The several deep coves along the lower reaches of the river are home to a number of commercial lobstering boats.

The project, completed in 1903, consists of a channel extending about one mile upstream from deep water in the Saint George River in Thomaston to Thomaston Harbor. The channel is 16 feet deep and has a width that varies between 90-220 feet.