Barge operators had lessened their loads as the river's level fell, allowing the barges to sit higher in the water. But there have been concerns for months that if the water level fell much more, all barge traffic could be halted.

The recent reversal of that has the Army Corps of Engineers and the Coast Guard declaring victory, though they cautioned the threat to shipping on the vital corridor could return next winter as the nation's worst drought in decades has shown no signs of easing.

"I'd say we've gotten through the toughest period we're going to see in the low-water period," said Mike Petersen, a spokesman for the Army Corps of Engineers, which scrambled in recent months to clear rock pinnacles from a crucial stretch of the Mississippi south of St. Louis.

With recent storms that socked the nation's midsection with snow and rain, "Mother Nature met us halfway, and that's what we needed," Petersen added. "But it also took tremendous elbow grease to keep that open. We're all a little bit weary, but we're relieved to see the river come up and not have any groundings."

The Mississippi had been growing ever shallower with the drought and a seasonal cutback on the amount of water fed into it from the Missouri River at St. Louis. Barge operators compensated by lightening their loads, which increased shipping costs because more barges were required to move the same amount of cargo. That also caused towboats to go through more fuel because more trips became necessary.

As the industry worried a shutdown could be imminent, the Army Corps scrambled to keep the river at a minimum of 9 feet deep for safe barge navigation. For months, the river hovered just a few feet — and at times a few inches — above that level.

Blasting and removal of rock pinnacles added 2 feet of depth at a troublesome southern Illinois stretch, and recent storms fed the river and its tributaries.

On Wednesday, the river gauge at St. Louis showed a channel depth of about 18 feet. The National Weather Service said it expects the river to rise another 2 feet through the weekend before a gradual decline. But that forecast assumes no additional precipitation, and the approaching spring months typically are among the wettest of the year.

At AEP River Operations, the river's comeback had Marty Hettel cheery. The company had parked many of its 3,100 barges and roughly 100 towboats as the river fell. But in recent days, AEP is back to loading barges to traditional levels, said Hettel, the company's senior manager of bulk sales.

"I'm sitting here telling you today that we're gonna get through this thing without any more obstructions. It's quite a relief," Hettel said. "On Dec. 31, it looked like the river was gonna be shut down (by early January). It was very touch and go, but timely rains helped us out. And kudos to the corps."

While calling the river's rise "a good-news story," an executive with the Waterways Council Inc. trade group said Congress still must address the river's aging system of locks and dams or risk the prospect of frequent infrastructure failures closing the corridor. Still, Debra Colbert said, "we really dodged a bullet."

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Associated Press writer Jim Salter contributed to this report.