CHARLEROI, Pa.—The locks on the Monongahela River near Charleroi will be closed through Aug. 3, meaning cargo barges and pleasure boaters won't be able to pass through the river at that point, about 20 miles south of Pittsburgh.

The U.S. Army Corps of Engineers says the chamber of Lock No. 4 is being drained starting Monday so crews an fix the miter gate sills, the filling valves and related machinery.

The work was scheduled to begin Monday.