Alaska capital takes stock after worst flooding yet caused by retreating glacier | Alaska

Residents in Alaska’s capital cleared out waterlogged homes on Wednesday after a lake dammed by the picturesque Mendenhall Glacier gave way, causing the worst flooding in Juneau yet from what has become a yearly phenomenon.

At least 100 homes and some businesses were damaged by rapidly rising floodwaters that crested early on Tuesday, according to initial estimates. In some areas, cars floated in chest-high water as people scrambled to evacuate. The waters receded by Wednesday, and the river level was falling.

The flooding happened because a smaller glacier nearby had retreated – a casualty of the warming climate – and left a basin that fills with rainwater and snowmelt each summer. When the water creates enough pressure, as happened this week, it forces its way under or around the ice dam created by the Mendenhall Glacier, enters Mendenhall Lake and eventually makes its way to the Mendenhall River.

Since 2011, the phenomenon has at times flooded streets or homes near Mendenhall Lake and Mendenhall River, and last year floodwaters devoured large chunks of the riverbank, inundated homes and sent at least one residence crashing into the raging river.

But this week’s flooding was unprecedented and left residents shaken as they tried to dry out furniture, important papers and other belongings in the sun on Wednesday and filled trash containers with sodden insulation and carpeting.

While the basin was created by glacial retreat, climate change plays almost no role in the year to year variations in the volume of the flooding in Juneau, said Eran Hood, a professor of environmental science at the University of Alaska Southeast who has studied the Mendenhall Glacier for years.

The glacial flooding, however, is a reminder of the global risk from bursting snow-and-ice dams – a phenomenon called a jökulhlaup, which is little known in the US but could threaten about 15 million people around the world.

The city of about 30,000 people in south-east Alaska is reachable only by plane or boat and is already struggling with a housing shortage that could limit the temporary accommodations available for flood victims. Juneau also has limited rental car agencies for those whose vehicles were swamped.

Resident Alyssa Fischer said her father woke her up early on Tuesday via FaceTime and told her about rising water outside. She helped him move his cars to higher ground, as well as her pet quail, before evacuating with her four- and eight-year-old children and pet duck and goose to a shelter at the local middle school.

On Wednesday she was relieved that damage to her property was mostly limited to a crawl space and the garage. But she worries about the future and does not feel safe.

“This seems to be a big issue, and I don’t think it will lessen,” Fischer said.

The Mendenhall River crested early on Tuesday at 15.99ft (4.9m), a new record, topping the level during last year’s flood by over a foot, and the water reached farther into the Mendenhall Valley, officials said. The city said the high water even reached some homes outside expected flood areas. The valley is roughly a 15- to 20-minute drive from downtown Juneau.

The National Weather Service said late last week that the water level in the basin had reached the top of the glacier and warned people to prepare for flooding. The city urged residents in the area to have an evacuation plan and to spend Monday night elsewhere, and it also opened an emergency shelter.

No injuries were reported. The Alaska governor, Mike Dunleavy, issued a disaster declaration to aid the response and recovery.