The U.S. Coast Guard says the closure was to allow dredging to deepen the waterway.
Chief Petty Officer Scott Vincamp says a four-mile stretch from mile marker 162 to mile marker 158 was closed at 3 a.m. Monday morning. A three-mile stretch from mile marker 168 at the Jefferson Barracks Bridge just south of St. Louis to mile marker 165 was closed for dredging from Friday until Sunday night.
Barge traffic was allowed to pass during the intervening hours when the river was open.
Vincamp says any further dredging would depend on future river levels.