McClatchy Newspapers

Congress is reviving legislation to create a trail that would trace the route of catastrophic ice-age floods that left scars across the Pacific Northwest.

Visitors could drive the 600-mile trail and stop at interpretive centers and roadside pullouts to learn about the floods that were unleashed when an ice dam in what’s now Montana collapsed, draining a lake the combined size of Lake Erie and Lake Ontario in two days.

The 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 Senate last year but died when the session ended before differences with the version that the House passed could be resolved. Cantwell said she expects the measure to pass Congress this year.

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

The floods occurred 13,000 to 18,000 years ago during the last major ice-sheet expansion.

The ice dam that blocked the Clark Fork River near what’s 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 group from Richland, Wash., that has extensively studied the floods.

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.

After passing through the Columbia River Gorge, the flood backed up into Oregon’s Willamette Valley, covering the Portland area 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, creating coulees, buttes, boulder fields, lakes, ridges and gravel bars that remain today.

The floods provided much of the fertile soil that’s found in the Willamette Valley and left behind the 189-foot Palouse Falls in Eastern Washington as well as 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.

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

On the Net:

Learn more about the ice age floods

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