The barges that ply the Mississippi from Minneapolis to St. Louis go up and down a long flight of stairs: the 29 locks and dams on thsi upper stretch of the river. Overseen by the U.S. Army Corps of Engineers, the locks are massive tanks that fill and empty as they lift and lower barges to accommodate the river's changing water levels. The Corps now wants to rebuild the locks, saying that the current system can no longer effectively carry grain and other key Midwestern exports out into the global market. Critics argue that the project would pour a lot of concrete and money into the Mississippi to fix an imaginary problem, at great cost to taxpayers and to the river itself.

As the Corps and its allies in the barge industry see it, almost all the lock-and-dam facilities along the 663-mile stretch of river are just too small to handle the traffic. A standard barge, about 195 feet long and 35 feet wide, usually travels in a raft made up of several such barges, guided by a single towboat. There's room enough inside the 600-foot locks for, say, eight barges lashed together, whereas a few newer 1,200-foot locks can handle at least twice that number. The bigger rafts -- now quite common -- have to be broken down on one side of the smaller locks and reassembled on the other, increasing the passage time from half an hour to as long as an hour and a half.

Upgrading the facilities would cost $2.1 billion over 20 years. The growing opposition to this proposal includes many environmental groups, and the Institute for Agriculture and Trade Policy (IATP). They say the Corps has exaggerated the problem and they question the wisdom of tearing apart a river already ecologically ravaged by the Corps' previous projects. Cheaper, simpler measures could improve the situation with far less environmental impact, they say.

The Corps' proposal ignited controversy in 2000, when Corps economist Donald Sweeney revealed that the agency's economic analyses had been manipulated in order to justify the project. The whistle blowing led to a Washington Post investigative series on the Corps' practices. A subsequent review by the National Academy of Sciences' National Research Council reached similar conclusions and recommended that the Corps revise the report, this time without cooking the data.