Alaska authorities assess damage after glacial dam outburst

JUNEAU, Alaska >> Raging waters that ate away at riverbanks, destroyed at least two buildings and undermined others continued to recede today in Alaska’s capital city after a glacial dam outburst over the weekend, authorities said.

Levels along the Mendenhall River had begun falling by Sunday but the city said the banks of the river remained unstable. Onlookers gathered on a bridge over the river and along the banks of the swollen Mendenhall Lake to take photos and videos Sunday. A home was propped precariously along the eroded river bank as milky-colored water whisked past. The city said it was working to assess damages.

There were no reports of any injuries or deaths.

Such glacial outburst floods occur when glaciers melt and pour massive amounts of water into nearby lakes. A study released earlier this year found such floods pose a risk to about 15 million people around the globe, more than half of them in India, Pakistan, Peru and China.

Suicide Basin — a side basin of the Mendenhall Glacier — has released water that has caused flooding along the Mendenhall Lake and Mendenhall River since 2011, according to the National Weather Service. However, the maximum water level in the lake on Saturday night exceeded the previous record flood stage set in July 2016, the weather service reported.

Nicole Ferrin, a warning coordination meteorologist with the National Weather Service, said that while it’s not uncommon for these types of outburst floods to happen, this one was extreme.

“The amount of erosion that happened from the fast moving water was unprecedented,” she said.

Water levels crested late Saturday night. Video posted on social media from the flooding showed towering trees falling into the rushing river as a home teetered at the edge of the bank and eventually collapsed into the river.