Barge traffic on the Upper Mississippi River dropped below the 10-year average this year as parts of the river have seen record-low levels due to drought.
The U.S. Army Corps of Engineers recorded 9,790 barges through its southernmost lock in the Corps’ St. Paul District that extends from Minneapolis to Guttenberg, Iowa. The number of barges moving on the river bordering Minnesota and Wisconsin is down around 20 percent from the 10-year average. Barges shipped around 11.7 million tons of commodities — down from roughly 13 million tons last year.
"If we have high water that oftentimes will delay movement up here in the spring, and then a year like this where you have low water down south where barges there may be having to load barges lighter, or they're just not able to get up here as timely, that definitely will impact things," Corps Navigation Manager Kristin Moe said.
While the weather can affect harvests, the lower barge numbers highlight the impact of low water levels. Movements on the lower river were 31 percent below the three-year average for the week ending Dec. 10.
Grain from Wisconsin transported on the river is typically bound for domestic ports, countries in the Caribbean, and Central and South America. Mark Rhoda-Reis, director of the state’s International Agribusiness Center, said ag officials aren’t hearing from companies that lower water levels have hit grain shipments hard. Overall, the state’s agricultural exports are up nearly 14 percent this year.
"It affects them in terms of their pricing, what they have to pay for shipping those products," Rhoda-Reis said. "And of course, it affects their profitability."
The Upper Mississippi River has seen less than normal precipitation this year, according to Dan Fasching, the Corps’ primary Mississippi River regulator in the St. Paul District. Water flowing into the river from major tributaries like the St. Croix, Chippewa, and Wisconsin Rivers has also been lower this year. Even so, drier conditions haven’t affected navigation due to the river’s system of locks and dams. Fasching said they’ve been able to regulate inflows and outflows to maintain a minimum depth of 9 feet for barges.
"The fact of the matter is below St. Louis, they do not have navigation locks and dams that allow for minimal navigation depths like we do up here," Fasching said. "They really do rely on high inflow."
The lack of rain in the Ohio River Valley and Upper Mississippi River Valley caused water on parts of the river to drop to levels that hadn’t been seen in more than a decade.
"Over the last few years with these high waters, it's actually been perhaps too much water, and it's killed some of the forests by drowning out the trees. And we're actually starting to see ghost forests on the river where there's mass tree mortality," Larson said. "In the coming years, those trees will fall down. But, this year with falling water levels finally those roots are able to dry out and the tree’s roots are able to breathe."
As water levels fall, marsh plants and floodplain forests are able to regenerate and reproduce. If lower flows continue, she said that could pose negative impacts for native mussels or certain fish moving up the river to spawn.