Mississippi River lock-and-dam system is outdated and in disrepair. What if it fails?

The lock-and-dam system through which 175 million tons of freight travels on the upper Mississippi River each year is sorely outdated, and vulnerable to failure that could have a profound effect on the economy.

“Is it a matter of if you have a failure … or when you have a failure?” said Mike Steenhoek, executive director of the Soy Transportation Coalition.

Steenhoek likened the system to a fire hydrant hooked up to a garden hose. Traffic on the river continues to increase, with farmers producing significantly more corn and soybeans for export than they were when the locks and dams were built almost a century ago. At that time, engineers estimated their lifespan to be about 50 years.

If the upper Mississippi River had to shut down for one season because of lock and dam failures, the amount of agricultural goods displaced would equal between 367,000 and 489,000 loads by truck, according to a 2017 study from the University of Wisconsin-Madison, with the Mid-America Freight Coalition. It could cost up to $283 million to move those loads by truck, and upwards of $300 million if road damage is taken into account, the report said. And those estimates — the most recent available — were from six years ago. Today, according to the Consumer Price Index, the cost likely would be above $350 million.

Even then, "The true cost of a river shutdown would be much greater, as it would raise the cost of shipping for multiple commodities and reduce the economic competitiveness of the Upper Midwest," the report said.

Commodities are moved on the river in a well-choreographed ritual. They are loaded onto barges, which are then pushed by towboats. Most towboats can push 15 barges at a time, essentially creating a water-borne train about 1,200 feet long.

The locks allow the boats to gradually adjust to changing river levels. But when the boat-and-barge setup reaches a 600-foot long lock, it can't all go through at once. Instead, it has to be split into two groups — first some of the barges, and then the remaining barges plus the towboat — which takes more than twice as long.

Those delays keep growing because of the increase in goods being moved. A 2019 Agribusiness Consulting report found that in 2017, more than half the boat-and-barge setups on the river were delayed at locks and dams, up from about one in five in 2000. Delay time increased from 90 minutes to about 122 minutes, some of the longest in the country.  

Steenhoek said farmers ultimately foot the bill. If shipping companies face slowdowns on the river that cost them more in fuel, they’ll lower the price they’re willing to pay farmers for the product. 

Almost everyone involved agrees that something needs to be done about the locks and dams, which have an estimated $1 billion backlog of maintenance costs. 

Yet with so many varied interests, the question of who should pay – and what exactly to pay for – isn’t easy to answer. 

“We’re doing repairs … to keep it operational,” said Kristin Moe, navigation business line manager for the U.S. Army Corps of Engineers’ St. Paul (Minnesota) District. “But at some point, we’re going to need some major rehabilitation of these structures.” 

More: Biden infrastructure law has funded $220B in projects so far. But are Americans noticing?

Locks and dams far past expected lifespan

As the Midwest’s agricultural and manufacturing economies developed in the 20th century, it became increasingly hard to move goods on the upper river, which at times was so shallow that people could walk across it. As early as the 1830s, there was interest in controlling the river’s whims to give commercial traffic easier passage. 

In 1930, Congress approved a project that would ultimately create the current system of 29 locks and dams that stretches from Minneapolis to Granite City, Illinois. The upper river is divided into sections called pools, where a fixed amount of river is held back by a dam. The Army Corps controls how much water is in a pool at a given time. Each pool must be at least nine feet deep to allow barges to move through. 

Between the headwaters in northern Minnesota and Granite City, the river falls about 420 feet in elevation. Each lock acts like an elevator, bringing boats up or down to the water level of the next pool. 

The lower river does not have locks and dams. As major rivers like the Missouri and the Ohio join up with the Mississippi, the channel becomes deep and wide enough to naturally accommodate shipping. 

When the locks and dams were constructed – mostly between 1930 and 1940 – engineers estimated their lifespan to be about 50 years.

Today, in additon to the outdated infrastructure, there’s another piece of uncertainty to contend with: the changing climate, which brings weather extremes that will have their own effect on river shipping. Last fall, intense drought halted barge traffic on the lower Mississippi River, and this spring, severe flooding on the upper river did the same thing. 

“Having this pendulum swing … it’s very jarring to anyone who uses the system,” Steenhoek said. 

Those changes make it even more important to do preventative maintenance of the locks and dams, he said. 

More: These US cities may be best to escape worst impacts of climate change

How new projects and maintenance are funded

Taxpayers have been funding inland waterway infrastructure for nearly two centuries, but Congress established the Inland Waterways Trust Fund in 1978, which required the private shipping industry to pitch in. 

Today, the trust fund’s coffers are filled by a 29-cent per gallon diesel tax on commercial operators that use the Mississippi River and other inland waterways, adding up to about $125 million per year in recent years. New construction is paid for through a public-private partnership: the private dollars in the fund, which cover 35%, and federal dollars, which contribute 65%. 

But once the projects are completed, it’s taxpayers who pick up the tab for maintenance and repairs through federal funds. Thus the debate becomes not only how much each stakeholder should pay, but what projects should be paid for.

“We don’t need new waterways infrastructure,” said Olivia Dorothy of American Rivers, a group that works to protect and restore the nation's rivers. “We don’t need new dams. We don’t need new locks. We don’t need new stuff. We need to maintain the stuff that we have.” 

American Rivers has long advocated that companies using the waterway the most should pay the most to maintain it, similar to the highway funding model, which leverages fuel taxes, vehicle registration fees and other fees. The Inland Waterways Trust Fund is the most successful effort in Dorothy’s eyes, but it can't be used for the long list of backlogged maintenance projects, like repairing concrete walls and replacing gates.

Those who represent shippers – like the Waterways Council, a public policy group that advocates for an efficient inland waterways system – disagree. Deb Calhoun, the group’s senior vice president, said the system should be modernized so that every lock has a 1,200-foot chamber, which would allow today’s larger tows to move upriver and downriver faster. 

The construction of one of those larger chambers, at Lock 25 in Winfield, Missouri, began May 19, bolstered by funding from the federal infrastructure law. It marks the first of seven such projects to receive funding under the Army Corps' Navigation and Environmental Sustainability Program, an effort to address navigation concerns along with environmental ones. A group of senators, including U.S. Sen. Tammy Baldwin of Wisconsin, has asked for $120 million from Congress in fiscal year 2024 to make sure the program has enough money to continue its work.

Because the amount of goods traveling on the river is expected to increase, money shouldn’t be spent on rehabbing existing structures, but instead on building new ones, Calhoun said. 

The Waterways Council is opposed to additional toll or lockage fees for shippers that use the river, an idea that has been sometimes floated to fund repairs. Calhoun said it’s not just shippers who benefit from an efficient river. 

“The Mississippi River is a natural gift to the U.S., and it has beneficiaries like recreational boating and fishing, waterfront property development, and water for manufacturing processes,” she said. “None of those beneficiaries pay for the dedicated (diesel) fuel tax.” 

More: New York City is sinking, study says: Huge buildings, rising seas contribute to subsidence

Proposed model would have shippers pay up front

One proposal by an Iowa State University professor puts a spin on the public-private partnership model. It would ask shippers to foot some of the bill for lock and dam repairs up front and directly, instead of through the diesel tax, in return for quicker passage on the river.

Yoshinori Suzuki, the school’s Land O’Lakes Endowed Professor of supply chain management, argues in a study published in January in Transportation Journal that shippers could make a sound investment by covering 60 to 80% of the cost.

Suzuki said his model is already of interest to shippers. The study was paid for by Iowa State’s Supply Chain Forum, which includes corporate partners like Land O’Lakes, Cargill and Kent Corporation. Suzuki said companies are “deeply concerned” with the aging system, and that they were interested in the idea even before he presented the results. 

“Most, if not all, are very willing to provide funding to this kind of project as long as the investment comes back in positive return,” he said. 

Land O’Lakes and Kent Corporation did not respond to a request for comment about the study findings. A spokesperson for Cargill said the company had not yet been presented with the research. 

Suzuki acknowledged that there’s a lot left to figure out before his proposal could be put into action, like who would ultimately approve such a funding model and which entity would be in charge of spending the money. 

The model also relies on all shippers who use the river pitching in, which could take significant convincing. Calhoun, with the Waterways Council, said she doubted it would come to pass. 

Moe said the Corps is open to partnerships that could help them explore more innovative ways to fund repairs, including a public-private one. 

In the meantime, the Corps will keep chipping away at the system's needs, while age keeps chipping away at the system itself.

“It’s just a matter of: Can the funds keep up with this growing maintenance backlog?” she said. “This aging infrastructure is getting older every day.”

This story is a product of the Mississippi River Basin Ag & Water Desk, an editorially independent reporting network based at the University of Missouri School of Journalism in partnership with Report For America and the Society of Environmental Journalists, funded by the Walton Family Foundation.