– In the bowels of the Dredge William L. Goetz, anchored off the Wisconsin side of the Mississippi River, the deafening drone of twin Caterpillar power generators are cranking at their full 1,200 rpm, generating more than enough megawatts to light a town the size of nearby Wabasha.

Heavy steel cables strain as the dredge’s cutterhead, a nasty-looking steel-toothed ball carried on a large boom, churns into a sandbar below the river’s surface.

The cutterhead stirs up the sand, which is then sucked into a network of large pipes strung along a line of barges that carry it to shore, adding to a mountain already about 50 feet high.

Over the past several weeks, a 52-member crew from the U.S. Army Corps of Engineers has been feverishly battling the clock and Mother Nature to clear the river of silt deposited by this year’s relentless floodwaters. That buildup has caused one of the worst barge traffic stoppages in memory, and one that could have far-ranging economic effects.

As of Monday, there was a glimmer of hope that the river could be cleared for commercial river traffic by this weekend.

But for now, the Corps said, 17 towboats with more than 150 barges — most of them loaded with cargo — sit moored to the shore along the Upper Mississippi, unable to budge because the shoals have made it impossible to move at the height of the river shipping season.

More are waiting in St. Paul.

“We have something like $50 million in commodities that are waiting to go,” said Lee Nelson, president of Upper River Services, which runs towboats in and out of St. Paul’s harbor.

While barges carrying such things as corn and soybeans, scrap steel and petroleum coke are waiting to head south, their return loads are just as vital to the region’s economy, Nelson said.

Barges are one of the chief transports for cement and road salt from the South. A shortage of cement could reverberate through the construction industry, and a reduced supply of road salt, already depleted from a prolonged winter with heavy snow, could strain the budgets of state and local agencies.

And looming on the horizon is the fall harvest. An estimated 60 percent of all U.S. grain exports are shipped on the Mississippi through New Orleans and the Port of South Louisiana.

“Grain needs to be south for export in a few weeks,” said Rick Calhoun, president of Cargo Carriers, the shipping business of Wayzata-based Cargill Inc., which has a fleet of 1,250 barges on the river.

While commercial traffic disruptions are part of doing business on the river, this stoppage has been unusually difficult, Calhoun said, because “We’ve just lost so many days.”

If shippers can’t get promised grain to ships destined for foreign ports on time, he said, it means buying grain from other sources to meet those obligations. That makes it imperative to clear the river as quickly as possible.

“The problem is, when you squeeze the balloon here, the air comes out someplace else,” Calhoun said.

There are other means of transport, but barges are economical, efficient and readily available — when the river is clear. Ten barges can carry the same tonnage as 150 rail cars or 600 semitrailer trucks.

The stoppage, Calhoun added, points vividly to how fragile, and important, the Mississippi shipping lane is to commerce. Calhoun, a longtime advocate of improving the lock and dam infrastructure that dates to the 1930s, said a malfunction of locks on the Upper Mississippi — which don’t have second locking chambers, unlike those farther south — could halt traffic for even longer than what is now being seen.

“[That] would absolutely have a devastating effect on Minnesota and Minnesota’s economy,” he said.

A vital link

Near Wabasha, just upriver from where the Goetz was dredging, the Big J.O. was among three towboats moored together. It’s one of 13 towboats owned by Yazoo River Towing Co. in Vicksburg, Miss., and the only one in the fleet that can’t go anywhere, said Patrick Smith, company president.

“It’s been a very big hit on us,” Smith said. “But I know the Corps of Engineers is working around the clock to clear up the channel. They do an amazing job.”

While the wait hasn’t been uncomfortable — modern towboats like the Big J.O., christened just this spring, have all the comforts, he added, including exercise rooms and computer access — the 10-member crew has been spending time getting the boat prepared for a fast and furious pace once traffic is moving again.

“That being said, there’s only so much cleaning you can do,” Smith added with a wistful chuckle.

It rains, and pours

This year’s shipping season was already off to a late start, with thick ice on Lake Pepin slow to melt. The traffic was just picking up when heavy rains began in April, and hit again in early June. As the rain fell, Mississippi tributaries, chiefly the Chippewa River in Wisconsin and the Zumbro in Minnesota, swelled and became a torrent, carrying with them tons of silt that tumbled quickly to the river bottom.

“I’d say it’s been a ragged year,” Nelson said.

More rain in late June was the final blow, with high water and fast currents forcing the Corps’ normal seasonal dredging operations off the river after they had barely gotten a start.

“That was the fourth high-water event of the year — it turned out to be a tough one,” said Jeff Hopkins, assistant master with the Corps of Engineers, helping supervise the crew that’s been working to clear a 9-foot navigational channel for barge traffic.

Along with the big Goetz, a smaller Corps dredge and several private contractors are working to unclog a portion of the river known as Pool 4, near Wabasha, which first closed on July 19; and a section near Winona called Pool 6, which closed July 23 after a towboat ran aground.

“Even if we can get the river open by [Friday], we’re not out of the woods,” said George Stringham, spokesman for the Corps in St. Paul. “There’s plenty of other places that need to be dredged, and dredged soon, or the river’s going to be closed again. This is going to be ongoing through the summer.”

Dredging is part of the annual maintenance routine for the Corps, but nothing like this year’s emergency operations, Hopkins added. His crew, many of whom are housed on the nearby Quarters Boat Taggatz, has been working in 12-hour shifts to clear the sandbars that formed when floodwaters quickly receded.

The dredging is a complicated process, he explained. Engineers first map the river bottom, then lay out a rectangular area called a “cut” for the 600-ton Goetz to eat into.

“People tend to think the sandbars are fairly evenly spread out, but they’re not,” Hopkins said. “It’s like sand dunes at the bottom.”

The varying depths are followed by Eric Carlson, leverman with the Corps, who controls the cutterhead with a joystick, guided by an array of computers acting as his underwater eyes. When it gets cranking, it can clear 2,000 cubic yards in an hour — more than 200 dump truck loads. Some of the sand is hauled off on barges, but most is piled on islands — stretching storage space in some areas. The Corps, Hopkins added, offers the sand for reuse.

The Corps has marching orders to maintain a 9-foot shipping channel, but the Goetz is going a little deeper — 12 feet — for good measure. “If we go a little deeper, hopefully we won’t have to be back here until next year,” Hopkins said.

While it works, the Goetz is held in position by a pair of huge stern vertical steel shafts called “spuds” — an improvement in technology on the old Dredge Thompson, retired two years after more than 65 years of river duty — that also nudge the boat forward by computer.

As Hopkins, piloting a support boat, zoomed past a group of idled towboats and their loaded barges on a recent afternoon, he spoke of the urgency of the crew’s work.

“They will get the mission done,” Hopkins said. “And we’ll be out here until we get it done.”