ST. LOUIS (AP) — A key stretch of the Mississippi River reopened to shipping Wednesday after hasty repairs were made to a lock damaged by a barge, marking the latest victory for stewards of the drought-plagued waterway they have maneuvered to keep open.

That crisis resolved, the Army Corps of Engineers is turning its attention back to the river' creep toward record low levels because of the nation's worst drought in decades. It remains confident the channel will be kept to at least the minimum depth required by barges.

This week's closure of Lock and Dam 27 near Granite City, Ill., unrelated to the drought, was forced after barge damaged a gate on an auxiliary lock before dawn Tuesday, causing a traffic snarl that swelled before the lock reopened 17 hours later.

By midmorning Wednesday, 85 barges and 15 vessels still were waiting to pass through — slow but steady progress from the 142 barges and 19 vessels that were idled there at the traffic jam's peak, Coast Guard Lt. Colin Fogarty said.

The speed in reopening that damaged lock was "pretty good," considering that the Army Corps had suggested the repairs could take days, Fogarty said.

Army Corps spokesman Mike Petersen said that agency expects the river to reach its lowest point in recorded history by late next month as drought continues to grip much of the nation. The extended National Weather Service forecast calls for the river to dip to minus-6.1 feet at St. Louis on Feb. 18, the latest date on its outlook. It could sink lower after that. The current record is minus-6.2 feet, set on Jan. 16, 1940.

Crediting months of efforts by the corps, Coast Guard and other river interests, Petersen said he expects the river to stay open even then because a 9-foot-deep channel — the minimum for barge traffic — can be maintained even at minus-7 feet on the river gauge.

The zero mark on the gauge was an arbitrary figure established in the 19th century, reflecting a level that experts then believed the Mississippi would never dip below.

The Coast Guard makes the final decision on whether to close stretches of the river, and Fogarty said it's possible that weight or size restrictions on barges may be tightened.

While reducing cargo weight helps barges ride higher, shipping costs increase because more barges are required to move the same amount of cargo and tow boats go through more fuel because more trips become necessary.

"The Coast Guard will do everything it can to keep this open," Fogarty said. "Right now as the river stands, we are head and shoulders above where we were just a month ago as far as being prepared for low water levels."

The biggest improvement in the middle Mississippi was near Thebes, Ill., where contractors used dredging barges and explosives in recent weeks to clear rock pinnacles, months ahead of schedule. But the corps has been dredging since summer in a roughly 200-mile stretch from St. Louis to Cairo, Ill., to help clear the channel.

"You look at all the dredging work, the rock removal — we've been able to get the channel down to where we could break a low-water record and still keep the river open," Petersen said. "You can't stop a drought by engineering around it, but you can definitely give yourself a reliable, resilient channel."

That work is helping now and will pay dividends in years to come if, as expected, the drought persists, he said.

"We might see low river levels next year," Petersen said. "Long-range forecasts have us looking at another dry winter."