Frequently dredging the Mississippi River helps to keep cargo moving, but places to 'stash' sand are in short supply

The Mississippi River near Wabasha, Minn., is a dredging
hotspot. (Photo by Elizabeth Flores, Star Tribune)

Frequent dredging kept cargo moving along the Mississippi this year, but moving sand from here to there has its own complications. "Historic low flows turned the Mississippi River into a construction area in 2023 as the U.S. Army Corps of Engineers dredged huge quantities of sand to keep the channel open for barge traffic," reports Chloe Johnson of the Minneapolis Star Tribune. "Massive machines like the Dredge Goetz, a 225-foot-long vessel with a suction pipe nearly two feet wide, were moving through the river constantly to keep it clear. . . . From May to July, 'day in and day out, we were digging,'" said Tom Heinold, chief of operations for the Rock Island District of the Army Corps of Engineers.

Extreme weather fluctuations make preparing waterways more difficult. Johnson explains: "A sudden drop in flow means the water in the river loses velocity, and all the sand flowing with it drops to the bottom." This year's snowmelt and sudden drought caused that scenario to unfold, with sand blocking up many expected "choke points" and clogging some unexpected areas.

Constant dredging is expensive and leaves the corps searching for places to "stash the sand." Johnson reports. "It's expensive work for the corps and the taxpayers who fund it – between surveying potential dredging areas, sucking the sand up and moving it into storage areas. The dredging program on the Upper Mississippi cost an average of $45.4 million a year between 2014 and 2023. . . . As the corps seeks new places to dump sand in the future, Sabrina Chandler, manager of the Upper Mississippi River National Fish and Wildlife Refuge, told Johnson, "I'm not sure that it's going to be a very simple fix."

While environmental advocates push for wildlife protections, the river's ability to ship remains the top concern. "It's a challenge to tease out all the impacts of dredging and sand placement. The upper Mississippi has already been chopped into 29 pools, each ending in a lock and dam to keep water high enough for shipping navigation. Since Congress required the 9-foot shipping channel in 1930, that navigation mission remains first and foremost for the corps on the river," Johnson writes. "Wildlife managers who bargain with the corps on sand placement are left looking for the least harmful scenario in a river system that has already been massively changed by human intervention across 145 years."