JUNEAU, Alaska — Residents of Alaska’s capital city emptied their flooded homes Wednesday after a lake dammed by the picturesque Mendenhall Glacier collapsed, triggering the city’s worst annual flooding.
At least 100 homes and several businesses were damaged by rapidly rising floodwaters on Tuesday night, according to initial estimates. In some areas, cars were floating in chest-high water as people rushed to evacuate. The water had receded by Wednesday and river levels were falling.
The flooding happened because a smaller glacier nearby retreated more than a decade ago — a casualty of the warming climate — leaving behind a basin that fills with rainwater and snowmelt each summer. When the water builds up enough pressure, as it did this week, it forces its way under or around the ice dam created by the Mendenhall Glacier, into Mendenhall Lake and eventually into the Mendenhall River.
Since 2011the phenomenon has at times flooded streets or homes near Mendenhall Lake and Mendenhall River, and Last year large areas were swallowed up by flood waters from the riverbank, flooding homes and causing at least one house to be submerged in the raging river.
But this week’s flooding was unprecedented, leaving residents in shock as they tried to dry furniture, important papers and other belongings in the sun on Wednesday and filled garbage containers with soggy insulation and carpets.
Although the basin was created by retreating glaciers, climate change plays virtually no role in the annual variations in flood magnitude in Juneau, said Eran Hood, a professor of environmental sciences at the University of Alaska Southeast who has studied the Mendenhall Glacier for years.
However, the glacial floods are a reminder of the global risk of snow and ice dams bursting – a phenomenon called jökuhlaup, which is little known in the U.S. but threaten about 15 million people around the world.
The city of about 30,000 in southeastern Alaska is accessible only by plane and boat and already faces a housing shortage that could limit temporary accommodations for flood victims. Juneau also has a limited number of car rental companies for those whose vehicles were flooded.
Resident Alyssa Fischer said her father woke her up early Tuesday via Face Time and told her to get out of her house as the floodwaters rose. She helped him move his cars to higher ground, as well as her pet quail and ducks, before evacuating with her 4- and 8-year-old children to a shelter near the local high school.
On Wednesday, she was relieved that the damage to her property was limited to a crawl space and the garage, but she worries about the future and doesn’t feel safe.
“This seems to be a big problem, and I don’t think it’s going to go away,” Fischer said.
The Mendenhall River crested at 15.99 feet (4.9 meters) Tuesday morning, a new record, surpassing last year’s flood level by more than a foot, and water reached farther into the Mendenhall Valley, officials said. The city said the high water reached some homes outside of expected flood zones. The valley is about a 15- to 20-minute drive from downtown Juneau.
The National Weather Service reported late last week that the basin’s water level had reached the top of the glacier and warned people to prepare for flooding. The city urged area residents to have an evacuation plan and spend Monday night elsewhere, and also opened an emergency shelter.
No injuries were reported. Governor Mike Dunleavy has issued a disaster declaration to aid the response and recovery.