Runoff from spring floods is also hampering barge traffic on the Mississippi. Two groups of barges ran aground Wednesday night near downtown St. Paul in a channel clogged by flood-deposited sediment. The Army Corp of Engineers will start dredging the channel tomorrow and expects to have it open by the middle of next week. Lee Nelson is President of Upper River Services, Inc. a barge servicing company. He says the sediment has been building up for three months: