Academy reviews debate over placing sediment in Missouri River

Tuesday, September 28, 2010 | 7:36 p.m. CDT; updated 6:04 p.m. CDT, Wednesday, September 29, 2010

This story has been modified to correct a summary of the findings of the National Academy of Sciences regarding sediment and nutrients that enter the Missouri River because of construction projects by the U.S. Army Corps of Engineers.

COLUMBIA — A two-year study has concluded that future decisions about water quality in the Missouri River should consider the fact that the river before regulation carried large amounts of sediment and nutrients that were important to its ecosystem.

The study — commissioned by the U.S. Army Corps of Engineers, the U.S. Fish and Wildlife Service and the Environmental Protection Agency in 2008 — was conducted by the National Academy of Sciences.

The federal agencies sought the study after the Missouri Department of Natural Resources' Clean Water Commission issued a cease-and-desist order in 2007 that forced the corps to stop work on shallow-water projects. Those projects were designed to create desirable habitat for wildlife, including the least tern, the piping plover and the pallid sturgeon, each of which is either endangered or threatened.

The Clean Water Commission argued that the corps practice of dumping sediment excavated during those projects into the river would pollute it, according to a previous Missourian story. That disagreement is what led to the independent study by the academy.

Col. Anthony Hofmann of the Kansas City District of the U.S. Army Corps of Engineers made a statement in a teleconference Tuesday summarizing the academy study results and its implications.

The report, which was overseen by the Water Science and Technology Board, sought to answer seven main questions regarding sediment in and from the river.

Aside from the need for wildlife habitat, the potential for sediment to pollute the river — and in turn, the Mississippi River and Gulf of Mexico downstream — was a major point of contention.

Hofmann quoted specific sections of the report in his statement, covering three major points deemed important by the Corps of Engineers.

He noted first that the river historically contained large amounts of sediment and that the report declared that returning sediment to the river would be advantageous to endangered or threatened animal species.

Hofmann cited page 42 of the report.

“High concentrations of sediment and high turbidity in the preregulation river were important to the evolution and adaptation of native species such as the pallid sturgeon,” the report reads.

Second, Hofmann cited academy findings that show phosphorus load levels that would result from reintroducing sediment to the river “will not significantly change the extent of the hypoxic area in the Gulf of Mexico,” also known as "the dead zone," per page 106 of the report.

Finally, Hofmann said that the study shows that if sediment is put back into the river, water quality will align with Clean Water Act standards.

"The legislative history and origins of the Clean Water Act show that it long has been recognized that historic watershed conditions can be a template for setting water quality uses and criteria."

The report is the latest chapter in a long-running dispute between state and federal agencies over how to properly manage the river to meet recreational, commercial and environmental interests.

Jennifer Walsh of the National Academy of Sciences said in an e-mail on Wednesday that the report emphasizes the importance of managing and monitoring the impact of sediment and nutrients that enter the river during or after corps constructive projects. That process, the report says, will be shaped by new science, possible changes in laws and water quality standards and "shifting social preferences regarding Missouri River management and resources."

Hofmann concluded his statement by saying the corps and other state and federal agencies will review the study further "to help determine a path forward."

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