Glacial Flooding Damages More Than 100 Homes in Juneau, Alaska

Glacial flooding damaged more than 100 homes and sent residents seeking shelter on Tuesday in Juneau, Alaska, in what has become a near-annual summertime occurrence. 

Last week, Juneau officials issued a warning that Suicide Basin, a side basin of the Mendenhall Glacier nestled just outside Juneau, had reached a level that meant flooding was possible. On Monday, water began rushing from the basin, prompting residents to seek shelter.

“There was a tremendous amount of water that came out at one time,” Aaron Jacobs, senior service hydrologist with the National Weather Service in Juneau, told The Washington Post.

Alaska Governor Mike Dunleavy declared the flood a disaster on Tuesday and said Wednesday that no fatalities were reported, but the damage from the flood was “significant.”

As glaciers in Suicide Basin melt, water levels rise, forming a glacial lake that is naturally held back by the Mendenhall Glacier. But the Mendenhall is thinning too. The water continues to rise until it reaches a tipping point from the pressure, bursting through the Mendenhall Glacier and moving into Juneau’s Mendenhall River.

The Mendenhall River crested early Tuesday at 15.99 feet, more than a foot higher than last year’s 14.97-foot flood, according to the National Weather Service.

The National Weather Service has monitored Suicide Basin since 1965, but had not reported a glacial lake outburst until 2011, reported Reuters. Since then, there have been more than 30.

The floods tend to get worse every year. Last year’s flooding saw record amounts of devastation at the time, including a two-story house that was swept away in the flood. This year’s has been even more destructive.

There was “significant inundation in neighborhoods that were not anticipating inundation,” said Juneau City Manager Katie Koester during a city meeting Tuesday, according to the Anchorage Daily News. City officials set up an emergency shelter in Floyd Dryden Middle School that had dozens of residents show up in just a few hours. Deputy City Manager Robert Barr said 43 residents stayed through the night, while many others sought shelter elsewhere.

The National Weather Service said the basin’s water levels had returned to normal on Wednesday.

Eran Hood, a hydrologist with the University of Alaska Southeast in Juneau, told The Washington Post, “The water level when it cut loose this year was lower than it was last year, but the basin was larger.” He added, “What we saw yesterday can happen again and likely will happen again in the future, and it could be bigger.”