Missouri, Mississippi Rivers Make Group's Most Endangered List With AM-Endangered Rivers-Glance

WASHINGTON (AP) _ Decades of pollution and emphasis on navigation over nature have landed the mighty Missouri and Mississippi on an environmental group's list of the 10 most endangered rivers.

Problems in rivers today result not so much from industrial pollution as from agricultural chemical runoff, dams and other engineering structures that have altered the natural flow of many rivers, and ill-treated sewage.

''There is a common perception that our rivers are better off than they were in the 1960s,'' said Kevin Coyle, president of Washington-based American Rivers. ''Today, we have a different message. There are problems throughout the country.''

The 1994 list is headed by the Clarks Fork of the Yellowstone River, a wild river in Wyoming and Montana brimming with trout that is jeopardized by a proposed nearby gold mine.

Others in the top 10 are the Anacostia River in Washington, D.C.; the Clavey River in California; the Columbia and Snake river system in the Northwest; the Penobscot River in Maine; the Rio Grande; Alaska's Thorne River and the Virgin River in Arizona.

Twenty other rivers were listed as threatened, including the Skokomish River in Washington state, the Chattahoochee River in Georgia and Alabama and the Everglades in Florida.

The Missouri River hardly resembles the ''Big Muddy'' explored by Lewis and Clark in 1804, the organization found. That sediment-filled river - the nation's longest - had meandering channels, sandbars, islands and sloughs.

Today, dams in the upper river regulate the flow, and the lower portion - from Sioux City, Iowa, to St. Louis - has been converted into a 732-mile barge shipping channel.

That has resulted in destruction of the natural features of the river, declines in some fish and wildlife species and loss of natural wetlands. One fish, the pallid sturgeon, is listed as endangered and two birds are threatened.

Yet the 12 million tons once forecast in annual shipping has never materialized. Shipping peaked at just 3.3 million tons in 1977, according to American Rivers. In contrast, the Mississippi River carries 380 million tons and the Ohio River carries 150 million tons.

''For a very marginal barge operation that goes up and down the river - essentially a subsidized operation - they are hurting the natural environment of the river,'' Coyle said.

The U.S. Army Corps of Engineers is conducting a study of the ''master manual'' it uses to operate the Missouri River. American Rivers is advocating a return to natural river flows, which could mean less navigation in the future. A draft of the study should be ready this summer.

The Mississippi River, a part of American culture as the setting of Mark Twain's ''Huckleberry Finn'' and a vital shipping route, made the list primarily because of the 1993 floods. Coyle said the floods showed that controls such as levees have created a tight channel that makes flooding worse.

Other problems include the straightening of the river along 2,000 miles of its length, which has destroyed fish and wildlife habitat and adjacent wetlands.

''If we continue on the course we are on, the Mississippi River will become little more than a lifeless barge canal,'' said Scott Faber, American Rivers' director of flood plain programs.