Sidecasting questioned

Big Rivers, the company hired by the corps to construct the Jameson Island chute, broke ground last winter and began disposing of the excavated dirt by depositing in the river. That was when farmers in Howard County got in touch with the Missouri Farm Bureau and the Clean Water Commission, fearing that dirt piling up on the opposite river bottom would force more water against their levee in the event of a flood.

In April, the Clean Water Commission asked the corps to stop dumping soil into the river. In a May meeting, the Commission reiterated its request. The corps maintained that any dirt the contractors had put into the river in March would wash downstream, and the agency went to some length to persuade farm interests in Howard County that this would be the case.

“We ran some models that showed that’s what would happen,” George said. When the river flooded in May, he said, “lo and behold, those soils did wash away.”

So the corps allowed construction crews to restart their engines in July. But given the objections raised by the Clean Water Commission, the newly excavated dirt was piled up along the chute in a process called sidecasting.

For the corps, sidecasting promised a cheaper and less controversial solution.

But it hasn’t worked out that way. Sidecasting didn’t satisfy either the Clean Water Commission or the Fish and Wildlife Service.

“What we would like to encourage is for the river to freely interact with its flood plain,” Watkins said.

Sidecasting, he said, creates an earthen wall that stops the river from seeping out into the habitat during high water and creates a barrier for wildlife.
In late September, the Clean Water Commission increased the pressure by sending the corps a cease and desist order that encompasses all of the agency’s habitat projects, including the completed chute at Overton Bottoms.

At the heart of the commission’s order is the assertion that the corps has not only been dumping dirt directly in the river but also incorporating soil erosion into its designs. The Jameson Island plan, for example, calls for construction of a chute with an initial width of 100 feet that would widen to 200 feet over time.
“What we’re trying to do,” George said, “is start a process and let Mother Nature have her way with it.”
Kristin Perry, who represents agricultural interests on the Clean Water Commission, makes little distinction between soil removed by contractors and erosion from natural processes.

“They call it planned erosion,” she said. “I call it river-digging.”

All told, she said, habitat restoration projects along the Missouri River stand to send almost 24 million tons of soil into state waters.

“That’s not a bucketload,” she said. “That’s a lot of dirt.”

One issue raised by the commission is that soil entering the river contains nitrogen and phosphorous, two nutrients blamed for the dead zone in the Gulf and a host of other water-quality issues.

George said the corps found that the soil at Jameson Island had less nitrogen and phosphorous than typical Missouri farm soil. It even had less than Missouri River water.

Agriculture takes the blunt of the blame for excess nutrients contributing to the dead zone in the Gulf, Perry said. She says federal agencies should also be held accountable.

Gossenauer said that all sources of nitrogen in the river system need to be carefully considered, so that even relatively small, unnecessary additions can be reduced.

Jacobson estimated that if all of the planned excavation, both manual and natural, for Jameson Island’s chute happened in one year, it would increase the river’s total sediment load by about 2 percent and the overall nitrogen level by 1 percent to 2 percent.

“The net effect on the river would likely be very small,” Jacobson said.

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