Diverted, Polluted, Dammed: America's Rivers in Jeopardy WASHINGTON, DC, April 2, 2002 (ENS) - The longest river in North America is the most endangered. The Missouri River tops the annual America's Most Endangered Rivers list issued today by the conservation group American Rivers.

It is the U.S. Army Corps of Engineers operation of a huge dam and reservoir system on the Missouri that changed the shape and ecology of the river. Today, 35 percent of the Missouri River is impounded, 32 percent has been channelized, and only 33 percent is unchannelized.

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Gavins Point Dam on the Missouri River in South Dakota (Photo courtesy American Rivers)
Releasing the list today, president of American Rivers Rebecca Wodder, said, "The Corps of Engineers' water projects have put more than 30 rivers on our endangered rivers list since 1986, sometimes more than once. It's time to get the Corps off its path of destruction and onto a new path of stewardship of our natural resources."

Each year since 1986, American Rivers has released the America's Most Endangered Rivers report to highlight rivers where imminent harm can be avoided or where ongoing destruction can be stopped. In the spirit of the FBI's "Ten Most Wanted" list, the report identifies dangers to rivers that can be avoided if action is taken. It is not a list of the nation's most chronically polluted rivers, the group says.

Four of the endangered rivers were placed on this year's list because of ongoing or proposed U.S. Army Corps of Engineers water projects. The Big Sunflower River in Mississippi, at number two, is threatened by a pair of Corps projects. The White River in Arkansas, at number five, is threatened by the Corps' plans to build an enormous irrigation project and hundreds of navigation structures. The Apalachicola River in Florida, at number 11, is being destroyed by the Corps' efforts to maintain a shipping channel for commercial barges that is rarely used, American Rivers charges.

Topping the American Rivers most endangered list for 2002, the Missouri River drains one-sixth of the United States. It flows 2,341 miles from its headwaters in the Rocky Mountains at the confluence of the Gallatin, Madison, and Jefferson rivers at Three Forks, Montana, to join the Mississippi River at St. Louis, Missouri.

The basin is home to about 10 million people from 28 Native American tribes, 10 states - Colorado, Iowa, Kansas, Minnesota, Missouri, Montana, Nebraska, North Dakota, South Dakota, Wyoming - and a small part of Canada.

The Missouri River reservoir system is the largest in the United States with a storage capacity of 74 million acre feet and a surface area exceeding one million acres. The six dams built in Montana, Nebraska, North Dakota and South Dakota transformed one-third of the Missouri River ecosystem into lake environments.

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Missouri River in flood, April 6, 1999. Looking southeast toward St. Louis, Missouri (Photo courtesy U.S. Army Corps of Engineers)
In the upper Missouri River, a new ecosystem has been created by the dams with the deep water reservoirs replacing the free flowing river. In the lower river, channelization has eliminated sandbars, depth diversity, and river connections with off-channel side channels and backwaters.

Great quantities of sediment and organic materials flow into the reservoirs and are trapped behind the dams, reducing reservoir storage capacity and sediment transport below the dams. Dams block native fish migration to spawning grounds and modify the flow regime in the river system.

In its report, American Rivers cites these dams and other Corps of Engineers water projects as a leading threat to rivers nationwide. The organization is urging Congress to pass legislation that will "put a stop to the agency's wasteful and destructive practices."

The Missouri River ecosystem is in "a serious state of decline," and the ecosystem faces the prospect of "irreversible extinction of species," the National Research Council of the National Academy of Sciences reported in January. Congress should enact legislation to ensure that federal officials manage the river in a way that improves ecological conditions, says the committee that wrote the report, "The Missouri River Ecosystem: Exploring the Prospects for Recovery."

American Rivers lists the other nine most endangered rivers in the United States as: