Geologic trail would trace the path of ice-age floods

WASHINGTON — Congress revived legislation Wednesday to create a geologic trail that would trace the route of a series of catastrophic ice-age floods that inundated much of the Pacific Northwest, leaving permanent scars across the region.

Visitors could drive the 600-mile trail and stop at interpretive centers and roadside pullouts to read signs and markers and learn about the floods that were unleashed when an ice dam in what is now Montana collapsed, draining a lake the combined size of Lake Erie and Lake Ontario in two days. The Ice Age Flood National Geologic Trail would cost $8 million to $12 million to create, and the National Park Service would oversee it.

The Senate Energy and Natural Resources Committee approved the measure Wednesday.

"The size and scope of what happened here is hard to fathom," Sen. Maria Cantwell, D-Wash., the prime sponsor of the bill, said of the floods. "This is one of the most unique events in the geologic history of the Earth. We usually see things like this on other planets."

Similar legislation cleared the full Senate last year but died when the session ended before differences with the version that the House of Representatives passed could be resolved.

Cantwell said she expects the measure to pass Congress this year.

"We seem more in sync," she said, adding that besides explaining a major geologic event, the trail would boost tourism and economic development in nearby communities.

Rep. Doc Hastings, R-Pasco, is sponsoring the House bill.

The floods 13,000 to 18,000 years ago came during the most recent major ice-sheet expansion as the ice dam, which blocked the Clark Fork River in the Idaho Panhandle near what is now Lake Pend Oreille, failed repeatedly. At its largest, Glacial Lake Missoula, as it's now known, was more than 2,000 feet deep and held more than 500 cubic miles of water, according to the Ice Age Floods Institute, a Richland-based group that has studied the floods extensively.

During the worst of the floods, a wall of water shook the ground as it swept down the Columbia River drainage across parts of Montana, Idaho and Washington state. Its flow was 10 times the combined flow of all the rivers in the world.

After passing through the Columbia River Gorge, the flood backed up into Oregon's Willamette Valley, covering the current site of Portland with 300 feet of water and reaching as far south as Eugene.

Sediment from the flood has been found in the Pacific Ocean hundreds of miles from the mouth of the Columbia River.

The floods redistributed more than 50 cubic miles of earth and rock, leaving in their wake coulees, buttes, boulder fields, lakes, ridges and gravel bars that remain today. The floods provided much of the fertile soil found in the Willamette Valley and in Eastern Washington and left behind the 189-foot Palouse Falls along with Dry Falls, which has a rim 10 times that of Niagara Falls.

"There is no doubt this is worthy of recognition and notice," Cantwell said.