ST. LOUIS (AP) — Barge operators along a key stretch of the Mississippi River braced Monday for months of restricted shipping as crews prepared to begin blasting large rock formations that are impeding navigation on the drought-plagued waterway.

Contractors from Iowa and Ohio could begin drilling holes into the troublesome Mississippi River bedrock south of St. Louis and detonating explosives inserted inside as early as Tuesday, the Army Corps of Engineers said. They expect to remove enough rock to fill about 50 dump trucks, possibly more.