The Mississippi River soon may be too shallow for barge shipping, which could hurt international trade and cause increases in domestic energy and food costs. Switching to other shipping methods could increase pollution.
However, there may be a bright side: Drought and reduced traffic on the desiccated rivers may benefit wildlife in the long run.
Last Friday, the Army Corps of Engineers began reducing the flow of water into the Missouri River from the Gavins Point Dam in South Dakota because of the continuing drought in the central United States. The Missouri is a major tributary of the Mississippi River, which means reduced flow in the Missouri results in a further drop in water levels on the Mississippi.
A crucial point in the river between St. Louis, Mo., and Cairo, Ill., may become impassible by approximately Dec. 10, according to a press release from the American Waterways Operators and the Waterways Council Inc., two organizations representing river shipping industry interests.
Trade in some of the most important commodities in America, such as coal and grain, stand to suffer from the stoppage of transport on America's main aquatic artery.
"For the coal that travels on the Mississippi, there could be impacts and delays in getting it to consumers in a timely way," Debra Colbert, senior vice president of Waterways Council, Inc., told Discovery News. "It will cost more to ship it by rail and or truck and consumers will pay more for heating and electricity as a result."
The exact effect on prices is impossible to estimate at this point, Colbert said.
Delays would affect 3.8 million tons of coal, according to the shipping organization's press release. Five million barrels of crude oil would be delayed, which may necessitate the import of $545 million worth of foreign crude. All together, $7 billion in commodities may be delayed.
Delays and cost increases in American grain shipments could affect the global food supply.
"River barge shipping is all geared to moving bulk grain exports for (livestock) feed uses overseas," said Bruce Abbe, executive director of the Midwest Shippers Association. " A huge share of the global market is served by American agriculture. Barge or water shipping is considered the most cost- efficient means for moving large quantities of bulk grains.
"If the drought continues more into next year, a larger percentage might go to the Pacific Northwest export terminals by rail," said Abbe. "Rail also can and does carry grain from the Midwest down to the Gulf."
Switching to rail and truck transport will affect American farmers' incomes and global consumer prices, Abbe noted.
"Cost will go up overall, for export customers and for suppliers here," said Abbe.
Along with increased costs, increased shipping via rail and truck also results in more pollution. Research by the U.S. Maritime Administration and the National Waterways Foundation calculated that:
- Inland waterway barge towing produces 19.27 tons of greenhouse gases per million tons of freight moved one mile, a unit known as a ton-mile.
- Container trucks produce 71.61 tons of greenhouse gases per million ton-miles.
- Rail transports produces 26.88 tons of greenhouse gases per million ton-miles.
On the other hand, the drought on the Mississippi might not be entirely negative for the environment.
Shipping causes localized disturbance to the Mississippi river's ecosystem as the barges and tugboats churn the water with their wakes and propellers, which can be six feet in diameter, according to Jon Duyvejonck, a biologist with the U.S. Fish and Wildlife Service.
During normal river levels, the turbulent waters and waves produced by ships can uproots plants in the loose, mucky soil of the river banks. A drought benefits the river by giving sediments on the river banks a chance to settle and form denser soil. After a drought, plants can become more resistant to the disturbance caused by boats. Duyvejonck noted that after a drought, a burst of plant growth in the solidified soil often proves to be a boon for wildlife.
Winter is a particularly beneficial time to reduce river traffic, Duyvejonck said.
"In winter, cold-blooded fish seek to reduce energy expenditure by resting in still waters," said Duyvejonck. "When ships pass, the fish must fight the erratic currents. Hence, a slowdown in traffic during December could help fish save energy and possibly result in an improvement in overwinter survival."
One ecological danger from ship traffic in low water is to mussels, which can't move out of the way of ships traveling through low waters. However, the ships themselves are not the biggest environmental problem caused by keeping the rivers open to transport during a drought. Duyvejonck said that finding a place to put the sand and silt dredged from the river's main channels can be the biggest environmental headache.
The Army Corps of Engineers began dredging ahead of schedule this year to battle the drought conditions, but were prepared for the low water this year by the flood last year, according to Mike Petersen, public affairs chief for the U.S. Army Corps of Engineers' St. Louis District.
"During the flood, Congress approved funds for river maintenance, so we had already done a significant amount of work dredging channels," said Petersen. "This year we have only needed two dredging ships working on the river, compared to the eight we had working during the drought of 1988 and '89."
Further plans for this year include blasting a group of rocks in southern Illinois that make the river especially treacherous in low water. The environmental effects of the blasting have already been assessed and the work approved in an earlier study of the region, said Petersen.
"One aspect to having a flood one year and a drought the next is that it keeps the Mississippi in the news and in the public's mind," said Petersen. "People tend to take the river for granted until there is a problem."