JUANA SUMMERS, HOST:
Juneau, Alaska, avoided catastrophe last week during what's called a glacial outburst flood. Each year, glacial melt caused by climate change fills up a pool until it bursts out into a river that runs through the suburban valley below. The past three summers have brought disastrous flooding, and the U.S. Army Corps of Engineers is working on a long-term solution. Alex Solomon of member station KTOO reports.
ALEX SOLOMON, BYLINE: Floods on the Mendenhall River due to the glacial outburst were minor until a few years ago when a couple of dozen homes were damaged. In 2024, about 300 homes flooded. Since then, the city has erected temporary Hesco barriers made of sand that have helped protect the town. And this year, just two households saw minor flooding.
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SOLOMON: Last week, Jeff Garmon pumped floodwater from a small pool that had formed in his backyard. He's a meteorologist for the National Weather Service in Juneau, and he lives on the river. In 2025, his bottom floor flooded when water leaked through the barriers. But this year, the floodwater didn't come up as high, and the barriers held.
JEFF GARMON: We're fortunate this year. We didn't have an atmospheric river going into this. I think that was our saving grace.
SOLOMON: Atmospheric rivers are storms that can bring a lot of water to the region at any time of year and raise the river. Glaciologists say that human-caused climate change created this threat. As two local glaciers melted, a basin of water dammed by ice formed and grew. Each summer, when the dam breaks, it releases the water and creates the flood. Eventually, the Mendenhall Glacier could retreat so much that the basin disappears, and this flooding threat won't exist anymore, but that could take an estimated 25 years.
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KATIE KOESTER: We don't need Hesco barriers for dozens of years. We need a long-term solution.
SOLOMON: That's city manager Katie Koester at a recent press conference. Officials don't know how high the water could get in future years, and they're concerned that it could top the barriers someday or launch a tree through a barrier which could create a flash flood. This year, about 2,000 homes were in the evacuation zone. 2026 might mark a big shift in planning a long-term solution. The day after the flood, the Army Corps announced that it's soliciting bids to drain the basin. Here's Brigadier General Clete Goetz at that same press conference.
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CLETE GOETZ: We'll hold a series of what we call pitch briefings. Really, if you've seen the show "Shark Tank," think that, where we'll have those meetings with industry, and from there, we'll select the best qualified to form an agreement with to design this.
SOLOMON: The Army Corps previously said the best way to drain the basin would be a tunnel that would steadily channel water out like a bathtub drain. They estimated it would cost between $613 million and $1 billion. Officials haven't specified that the solution will be a tunnel, and they haven't specified how construction will be funded. They plan to choose a contractor by the end of the year.
For NPR News, I'm Alex Solomon in Juneau.
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