In the twentieth century, the U.S. Army Corps of Engineers built six dams to control the seasonal rise and fall of the river to mitigate flooding and provide for barge travel on the river. However, barge traffic amounts to about one barge per day, and flood control measures could not control flooding in 1993 and 1995 said Ambrose.

Turning Point for the Missouri

American Rivers is a Washington-based nonprofit conservation organization dedicated to preserving rivers nationwide. Since 1988, the group has released a yearly Most Endangered Rivers report to call attention to rivers that face a crucial turning point in the coming year.

The group advocates a revised dam plan for the Missouri that would enable the dams to recreate seasonal rise and fall of the river. "Allowing for a spring rise in water levels, and lower summer flows, is a win-win-win for people, wildlife, and the economies of seven states," said Rebecca Wodder, president of American Rivers.

This year the Missouri faces a critical decision, said Wodder. The Army Corps of Engineers will release a new alternative for the Missouri River Water Control Manual, the guidebook used by federal river managers to regulate dam operations. American Rivers is urging the corps to adopt a U.S. Fish and Wildlife Service recommendation to increase river flows, restore floodplain habitat, and monitor closely the status of endangered species, which include the pallid sturgeon.

More than 20 million tourists are expected to visit the Lewis and Clark trail for the upcoming bicentennial of the Lewis and Clark expedition, said Ambrose. "We need to get started now so people can see part of what Lewis and Clark saw."

Power Crunch

Of the 13 rivers that made this year's endangered list, energy-related threats affect six, said Wodder.

Power is at the center of the dispute over Eel River, which is used to generate hydroelectric power for California. "[Hydroelectric plants] generate less than ten percent of the nation's power yet they cause a disproportionate amount of damage to rivers," said Wodder. Dams often drown wildlife habitat and block migratory fish from their spawning grounds.

Alaska's Canning River also made the list, as it abuts the controversial land in the Arctic National Wildlife Refuge. "It's threatened by oil and gas exploration that wouldn't deliver a drop of energy for a decade," said Wodder.

Also on the list is New York's Hudson River, which faces an important decision by the U.S. Environmental Protection Agency (EPA) over the cleanup of an estimated 200,000 pounds (91,000 kilograms) of polychlorinated biphenyls (PCBs) from a 40-mile (64 kilometer) stretch of river north of Albany, New York. PCBs were released into the river as a byproduct of electrical transformer production. The EPA ranks PCBs among the most toxic 10 percent of chemicals.

Still Endangered

Last year's most endangered river, Oregon's Snake River, was not listed this year because a major decision on its future is not pending, said Wodder.

In December 2000, the Clinton Administration released its salmon recovery plan, which outlined plans to improve habitat and river conditions while leaving four dams on the Lower Snake River in place. The dams could be removed as early as 2006 if salmon recovery is not achieved.

However, "the Snake and Columbia Rivers are now more endangered than ever," said Oregon Governor John Kitzhaber in a taped statement. Due to the power crisis in the West, federal agencies have been running the dams very hard to maximize electricity production.

Conservation officials estimate that if the dams continue to run at this capacity, 95 percent of this year's salmon run will be lost.

"As a nation, we have all reaped the benefits of the taming of these waterways," said Katzhaber. "As a nation, we must all share the burden of returning them to environmental health."