Last year historic floods forced evacuations along the Mississippi River and caused billions of dollars in economic damage. This year, a severe drought has lowered the water level causing boats and barges to run aground and reducing the flow of trade. Water levels are 50 feet below last year’s levels along some areas of the river.

Nearly 100 vessels were awaiting passage Monday along an 11-mile stretch of the river near Greenville that has been closed to boat traffic off and on since August 11 when a boat ran aground, according to the Associated Press. Low water levels had already been disrupting trade flows due to bottlenecking along the river.