EAST ST. LOUIS, Ill. (AP) - Environmental groups sued the U.S. Army Corps of Engineers on Thursday over the agency's use of man-made structures meant to keep the Mississippi River navigable, claiming the techniques provoke flooding as seen during historic inundations four times in the last two decades.
The federal lawsuit asks the Army Corps to resist building more "river training structures" such as wing dikes, arch-shaped dikes known as chevrons, and rock dikes called bendway weirs until it comprehensively evaluates their environmental impacts along the vital commerce corridor.
Such projects, the lawsuit claims, have "thoroughly transformed the Upper Mississippi River system to the detriment of wildlife," leaving that river stretch "in an extremely ecologically degraded state" and surrounding communities vulnerable.
"The risks to public safety will only increase as the corps constructs more river structures," the lawsuit says.
"We don't want to stop navigation by any means whatsoever. We are trying to keep the public safe," said Melissa Samet, senior water resources counsel for the National Wildlife Federation, a plaintiff along with the Prairie Rivers Network, Missouri Coalition for the Environment, River Alliance of Wisconsin, Great Rivers Habitat Alliance and the Minnesota Conservation Federation.
The Army Corps consistently has stood behind the projects, their engineering and environmental record, rebuffing requests by the wildlife federation to abandon the questioned river-management approaches that use the river's current to clear sentiment out of navigation channels, lessening the need for more costly dredging.
The groups argue that dozens of published scientific studies since 1986 link the construction of river training structures to increased flood heights. More than 15 studies from 2000 to 2010 suggest such Army Corps projects "significantly" elevated the mid-Mississippi's water levels, by 10 to 15 feet in some cases, posing a threat to riverside communities, the plaintiffs claim.
The wildlife federation says the more than 40,000 feet of wing dikes and bendway weirs built in the three years prior to the catastrophic flood of 1993 contributed to record crests in 1993, 1995, 2008 and 2011. Many more such structures have been added since, including at least 23 chevrons between 2003 and 2010, with more such projects in the works.
The Army Corps already has built more than 1,375 wing dikes, bendway weirs, chevrons and similar structures in a 143-mile stretch of the middle Mississippi River.
Combined with selective dredging, the structures help the Corps meet its congressional mandate to keep at least a 9-foot-deep channel for barge traffic on the river, officials with the Army Corps' St. Louis district told The Associated Press during a conference call. And the structures are taxpayer-friendly, far cheaper than constantly dredging, they said.
"It's a value-to-the-nation kind of thing," said Jasen Brown, the agency's project manager for the region.
Officials declined to address the lawsuit specifically, citing the pending litigation.
In a March 2012 response to the wildlife federation's letter urging the agency to reevaluate its river-management activities, Jo-Ellen Darcy - assistant secretary of the Army for civil works - said independent technical reviews it commissioned found that the river-training structures "do not raise the stage of the river and do not increase flood risk."
"Therefore, I do not believe that further studies are warranted or a moratorium on training structures should be imposed," Darcy wrote.
No hearing date on the lawsuit has been set.