The Mississippi system is a different story. While deteriorating locks on the Illinois and Upper Mississippi rivers present an ongoing restriction, the need for sustained dredging in the lower river is expected to become a limiting factor when the Panama Canal expansion opens in 2014.

Unlike the 50-ft. depths in some PNW ports, the Mississippi must by dredged to maintain a 46-ft. draft in its Southwest Pass.

Currently, Panamax ships transiting the Panama Canal are restricted to a 39.5-ft. draft, but in 2014 the expansion will allow for a 49.9-ft. draft. Even at the Mississippi’s current 46 ft., South Louisiana grain terminals will be unable to make full use of the canal improvements.

Meanwhile, the Army Corps of Engineers dredging funds aren’t adequate to maintain that 46-ft. depth, according to Paul Rohde, vice president of the Waterways Council. In fiscal 2010, for example, the Corps received $63 million to conduct $104 million worth of dredging south of Baton Rouge. This winter, just five dredges will work the lower river, compared to the nine normally needed for Southwest Pass alone.

“Without additional funding this year, we will see additional restrictions on draft. A 3-ft. draft loss means carrying 1,500-2,800 tons less cargo/foot,” says Sean Duffy, executive director of the Big River Coalition.

“This has real world implications, but reliability is an even bigger issue,” explains Rohde. If Japan and China want U.S. soybeans and we can’t get them out, or if our transport costs triple, that’s a real problem.”

A new Soy Transportation Coalition (STC) study suggests just how the pressures to move more commodities may grow with the Panama Canal expansion.

“The total volume of U.S. soybeans and grain moving through the canal to export markets could increase by 30%,” says Mike Steenhoek, STC executive director. “The average area that draws soy and grain to inland terminals for barge shipment down the Mississippi will expand from 70 miles to 152 miles.

“Each vessel will be able to accommodate 13,300 additional MT of cargo – about 490,000 bu. of soybeans, adding approximately $6 million to the cargo’s value and saving about 35¢/bu. in transportation costs for elevators within range of Gulf ports.”

But there’s a hitch, according to Steenhoek. U.S. growers and elevators will see those benefits only if port and channel depths are dredged to the federally mandated depth of 45 ft. – and if there’s no catastrophic breakdown in the lock system that feeds commodities down the river.