Environmental groups are asking a federal judge to halt several projects planned by the Army Corps of Engineers in the portion of the Mississippi River between St. Louis and the Ohio River.

In a lawsuit filed Thursday in the U.S. District Court in East St. Louis, six environmental groups are seeking to stop four projects the corps says are needed to reduce dredging costs and keep the river navigable.

One of the projects is on St. Louis’ riverfront, and the others are between the Missouri and Ohio rivers under the jurisdiction of the corps’ St. Louis district.

The structures used in those projects have been linked to increased flood heights by some academics, and the groups filing the suit say the corps has not taken new studies and information into account when preparing impact studies for projects. They also are seeking more comprehensive studies of the environmental impact corps activities have had on the river over the decades.

“There are definitely adverse environmental impacts but there are huge public safety impacts,” said Melissa Samet, a lawyer for the National Wildlife Federation, one of the plaintiffs.