( CNN ) -- An 11-mile stretch of the Mississippi River near Greenville , Mississippi , was closed Monday to most vessel traffic because of low water levels , idling nearly a hundred boats and barges in the stream , according to the U.S. Coast Guard . `` We are allowing a limited number of vessels based on size '' to attempt to pass , said New Orleans-based Coast Guard spokesman Ryan Tippets , adding that the closure was affecting 97 vessels Monday afternoon and was halting both northbound and southbound traffic . Salt creeping up the Mississippi River . This same area near Greenville , which sees about 50 vessels pass on an average day , has been closed `` intermittently '' since August 12 , when a vessel ran aground , said Tippets . The Coast Guard and the Army Corps of Engineers have continued surveying the area and deemed it `` dangerous for vessels to travel through , '' he said . The Army Corps of Engineers also has being dredging in the area to deepen the channel and help navigation . Complete coverage of the drought . A historic drought and excessive heat have reduced water levels and scorched wide sections of the U.S. Midwest . Flooding last year may have worsened the situation on the Mississippi by leaving deposits of silt and debris in areas that would normally be clear . Tippiets said he was unsure when the river would reopen or , once that happens , how long it would take to undo the gridlock . Interactive map : Watch drought overtake U.S. Are you affected by the drought ? Let us know on CNN iReport .
About a hundred vessels were idled by the closure . A Coast Guard spokesman said he is unsure when the port will reopened .