DRESBACH, Minn. – The Army Corps of Engineers has began moving 50,000 cubic yards of river-bottom muck in Pool 7 behind the Dresbach dam on the Mississippi River to a site near Trempealeau. The Corps asked boaters to be cautious near the worksite. A contractor, Legacy Corporation of East Moline, Illinois, is using barges to haul the dredged material. Barges will be making the 10-mile trip through August, the Corps said.