ST. LOUIS (AP) — Crews have completed the most critical phase of removing bedrock that threatened barges along a crucial stretch of the drought-starved Mississippi River, staving off the shipping industry’s fears that the treacherous channel could close to traffic, the U.S. Army Corps of Engineers said Saturday.

Using excavators and explosives, corps-hired contractors cleared 365 cubic yards of limestone and added two vital feet of depth to the channel near Thebes, Ill., about 130 miles south of St. Louis, the corps said. That phase, which began last month, addressed the most pressing threat to mariners and additional rock removal is expected nearby, the corps said.