Debris from melting glaciers chokes Mount Rainier rivers

The fallout from Mount Rainier’s shrinking glaciers is beginning to roll downhill, and nowhere is the impact more striking than on the volcano’s west side.

By Sandi Doughton, Seattle Times science reporter National Park Service geologist Paul Kennard walks over a portion of Tahoma Creek where glacial sediment has spilled into forest. Mount Rainier’s glaciers have shrunk dramatically. “Every year it’s been either bad or really bad,” Kennard said. “This year it was really, really bad.”
The fallout from Mount Rainier’s shrinking glaciers is beginning to roll downhill, and nowhere is the impact more striking than on the volcano’s west side. “This is it in spades,” said Park Service geologist Paul Kennard, scrambling up a 10-foot-tall mass of dirt and boulders bulldozed back just enough to clear the road. As receding glaciers expose crumbly slopes, vast amounts of gravel and sediment are being sluiced into the rivers that flow from the Northwest’s tallest peak. Much of the material sweeps down in rain-driven slurries called debris flows, like those that repeatedly have slammed Mount Rainier National Park’s Westside Road. “The rivers are filling up with stuff,” Kennard said from his vantage point atop the pile. He pointed out ancient stands of fir and cedar now up to their knees in water. Inside park boundaries, rivers choked with gravel are threatening to spill across roads, bump up against the bottom of bridges and flood the historic complex at Longmire. Downstream, communities in King and Pierce counties are casting a wary eye at the volcano in their backyard. There are already signs that riverbeds near Auburn and Puyallup are rising. As glaciers continue to pull back, the result could be increased flood danger across the Puget Sound lowlands for decades. “There is significant evidence that things are changing dramatically at Mount Rainier,” said Tim Abbe, of the environmental consulting firm ENTRIX. “We need to start planning for it now,” added Abbe, who helps analyze Mount Rainier’s river systems. Similar dynamics are playing out at all the region’s major glaciated peaks, from Mount Jefferson to Mount Baker, said research hydrologist Gordon Grant, of the U.S. Forest Service Pacific Northwest Research Station in Corvallis, Ore. Climate experts blame global warming, triggered by emissions from industries and cars, for much of the ongoing retreat of glaciers worldwide. North Cascades National Park has lost half of its ice area in the past century. Mount Rainier’s glaciers have shrunk by more than a quarter. “Every year it’s been either bad or really bad,” Kennard said. “This year it was really, really bad.” …