Floods from melting glacier in Juneau, Alaska, prompt evacuations and worry from residents

A rush of glacial floodwater swept down Alaska’s Mendenhall River on Wednesday morning, prompting evacuation warnings in parts of Juneau, seeping through flood barriers and flowing into a few neighborhoods.

The floodwaters, which broke through a dam of glacial ice, are an example of how gradual shifts to the climate are sometimes punctuated by sudden drama that can rapidly reshape a landscape.

Last year, hundreds of homes were flooded in Juneau when the river released a glacial outburst flood.

“We didn’t know it was coming,” said Elizabeth Startz, a Juneau resident whose home was flooded last year. “It did it overnight and neighbors were knocking on our windows and saying ‘Get out.’”

Startz said the risk of yearly floods might push her family away from the home they love and relocated to in hopes of escaping another flooding threat.

“We came from Texas, and we moved here to be away from hurricanes and flooding,” Startz said Tuesday, before floodwaters crested. “There’s no way I’m going to do this year after year after year.”

Historically, glacial outburst floods are not infrequent in Alaska, and most take place far away from communities like Juneau or critical infrastructure in the vast, sparsely populated state.

As the climate warms and destabilizes systems in parts of Alaska, experts said the threat from this type of flooding is not becoming more common, in part because glaciers are retreating. Instead, areas under threat are shifting, catching at least one community by surprise so far.

“For every one that has started forming, there’s one that has disappeared because the glacier no longer dams at that location,” Mauri Pelto, a glaciologist and professor of environmental science at Nichols College, said of glacier-dammed lakes.

The Mendenhall Glacier has produced yearly glacial outburst events since 2011, but most have been less significant than this year or last.

“Our beautiful glacier is melting,” Startz said, adding that she viewed climate change as the culprit. “This is the place to see it.”