Updated

For as long as people have been on the continental U.S., the Mississippi has been a major artery for commerce. The Coast Guard estimates that now $50 billion to $60 billion of commerce is pushed between the river's banks every year.

The river drains water from 40 percent of the U.S. mainland. So, when the U.S. is in a drought, the big river isn’t so big. In profound contrast to the near-record floods of last summer, the giant barges that carry everything from high fructose corn syrup, to grain, coal and diesel fuel are at risk of running aground. Sometimes they do.

“The Coast Guard is working hard with industry to insure that the impact is minimal. We have put some advisories in place,” says U.S. Coast Guard Lt. Cmdr. Michael Block.

Those advisories require shippers to draw less water with each barge so they won’t hit the bottom. That means decreasing the load by 25 percent. Instead of pushing 40 barges, each towboat can push only 30. So, in the end, each load moves slower and is less efficient.

When you go to fill your car's gas tank or put bread on the table, the burden for the low water comes out of your pocket.  “Freight is so much more expensive, it’s going to be passed on. I heard the other day food prices will go up 5 percent to 7 percent and this will be part of that increase,” says tow boat owner George Leavell.

A point of light may be that the Coast Guard only needs to put advisories in place, not restrictions. Coast Guard Capt. William Drelling says the shipping industry largely respects the advisories.

“It is in everybody’s interest to keep traffic flowing, to keep the river safe and environmentally sound. Nobody wants anything to happen, including industry, especially us.”

The shipping industry says a single barge carrying a load of dry cargo is equivalent to 70 trucks on the highway.  A barge carrying liquid cargo is the same as 144 tractor-trailers. So, a barge that runs aground and causes a closure of the river causes a staggering amount of cargo to get stuck behind the closure and even miss connecting shipments from the Gulf of Mexico.

Another bright spot is that the Army Corps of Engineers has been hard at work since the record lows of 1988. The corps attempts to keep the ever-changing river bottom dredged. Through the years a series of dykes and other infrastructure has been built to encourage water into the main shipping channels of the mighty Mississippi.

“It’s a different river now than it was in 1988. A lot of channel improvements have been made,” says Steve Perry of the Corps. “We invest a lot of money trying to keep the river following the channel that it is currently following.”

As a result of that effort, so far, the only complete closures of the river have been for nighttime navigation or until grounded barges are moved out of the way.

The bad news is that the historical low water months are August and September.