As demand for overnight river cruises on the Mississippi increases, the industry also faces increasing climate threats. Recent years have seen wild swings between heavy rainfall and severe drought, making the river tougher to navigate.

Low water levels forced cancellations last year, and climate experts fear that may happen again as it shapes up to be another dry summer, according to experts during a National Oceanic and Atmospheric Administration webinar July 6.

The most intense drought conditions are happening in the Midwest, throughout the upper Mississippi River basin, during what should be the rainiest season. Worsening drought upriver is raising red flags for the lower Mississippi, which relies on the Ohio River basin for about 60 percent of its flow. At St. Louis, the Mississippi River is about 10 feet below average for this time of year, with months to go until fall, its typical low season.

Low river levels could bring a cascade of challenges for ships on the Mississippi River. “Their docks may be affected, and they may not be able to get to them,” said Anna Wolverton, the NOAA liaison to the Army Corps of Engineers’ Mississippi Valley Division.

Last fall was a perfect storm of weather conditions: lower-than-normal rainfall, higher-than-normal temperatures and a longer-than-usual La Niña, which causes drier, warmer weather. This year could shape up to be the same, according to NOAA forecasters.

Viking launched its first Mississippi River cruise last September — a business venture that many saw as a vote of confidence in overnight cruises on the Big Muddy a decade after the industry’s return. But within a month of Viking’s debut, drought created trouble for companies that rely on the waterway.

Viking Mississippi set sail from New Orleans on Oct. 1 with hundreds of passengers on board. The two-week tour was supposed to end in St. Paul, Minnesota, but within a few days, barges were stranded on sandbars because of low water levels, and Viking’s boat was stuck for an entire day, waiting for the green light to continue upriver.

But Viking had to call off the rest of the cruise. It docked just north of Greenville, Mississippi, and bused passengers about three hours north to Memphis to fly home. Because the boat couldn’t continue upriver, it had to cancel its next trip, too, which was supposed to set sail from St. Paul for a trip downriver.

For barges, the key to continuing along the river was to decrease cargo and reduce the number of barges in each tow. With a lighter load, the odds of running aground a sandbar were much lower. Even then, some shippers turned to rail — a less efficient and more expensive method — to get cargo downriver, but cruise companies can’t detour and provide passengers with the same experience.

So last year, the three companies on the river — American Queen Voyages, American Cruises Lines and the newcomer, Viking — had to adjust itineraries, offer refunds and, in some cases, cancel tours altogether.

In the past century, the watershed has oscillated between very dry and very wet, which many Earth scientists believe to be the result of rising global temperatures. The National Integrated Drought Information System — NOAA’s drought monitoring branch — reports that annual lows are getting lower on the Mississippi. It’s one of the ways “climate change rears its ugly head,” according to Dorian Burnette, a professor who studies extreme weather events at the University of Memphis.

“If it’s dry, it’s gonna get drier. If it’s wet, it’s gonna get wetter,” Burnette said.

The Mississippi River’s flow can be slow to respond to changes, since the watershed drains more than 40 percent of the continental United States. It takes about three months for water that leaves Lake Itasa, the river’s primary source, to reach the Gulf of Mexico.

Over that period of time last fall, the river fell 20 feet, making it a flash drought. The National Weather Service has long provided flash flood warnings, but flash droughts are less understood and, as a result, not predicted with the same level of accuracy.

Cindy D’Aoust, president of American Queen Voyages, said that’s just part of the business. “Operating riverboats means that adjustments to itineraries are continually made due to river flow and changing river levels,” D’Aoust said.  

Robert De Luca, captain of the American Queen, said he’s seen the lingering effects of last year’s drought. “It definitely affected our business,” De Luca said. “To this day, we’re still trying to recover from that.”

Riverboat pilots must constantly adapt to the river as it fluctuates. In Memphis, when the river falls below seven feet — still above what the National Weather Service considers to be “low” — De Luca said the American Queen has to land a few miles upriver of Beale Street Landing at Greenbelt Park. Boats have to tie off to trees on the riverbank at Greenbelt Park, there’s no shaded area for passengers and crews have to run a hose to a hydrant more than 100 feet away to refill water.

The cruise lines are always developing contingency plans to keep up with a constantly changing river, but D’Aoust said the deviations last fall were unprecedented. At the time, Burnette and two other Earth scientists at the University of Memphis described the “dramatic plunge in water levels as a preview of a climate-altered future.”

For the shipping industry, Burnette said the future could involve more dredging to keep the river navigable, or adopting new water management practices. As the frequency and intensity of low-water events increase, Burnette said the industries that rely on the waterway must adapt.

For cruises, that could mean building itineraries around new seasonal weather patterns, but he sees the most room for improvement in forecasting.

This story, the second in a three-part series, published in partnership with the Mississippi Center for Investigative Reporting, part of Mississippi Today, is a product of the Mississippi River Basin Ag & Water Desk, an independent reporting network based at the University of Missouri in partnership with Report for America, funded by the Walton Family Foundation.

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