The Coast Guard says the Mississippi River is closed to shipping again after a barge grounded near Greenville, Miss.

An 11-mile stretch of the Mississippi south of Memphis, Tenn., reopened to limited vessel traffic late Tuesday after dredges were able to clear a channel.

Petty Officer Ryan Tippets said crews were working Wednesday to refloat the vessel and allow limited barge traffic to resume. It's not clear when the river will reopen.

Tippets says 33 northbound vessels were able to pass through the area before the grounding.

Low water is expected to hinder the flow of cargo from the nation's heartland until October.

A prolonged river shutdown could hamper operations of the busy port upriver from New Orleans that handles U.S. grain for export.