Juneau avoids widespread damage as new flood walls face glacier outburst

Glacier outburst flood

A glacier outburst flood occurred in Juneau, Alaska, after water surged from the suicide basin, a large pool dammed by the receding Mendenhall Glacier.

Flood protection measures

The Army Corps of Engineers installed two miles of Hesco sandbag barriers along the river before the flood. These barriers are credited with protecting almost 1,000 structures that might have been threatened by flooding.

Historical and ongoing risk

According to the Associated Press, annual glacier outburst floods have been a concern for Juneau residents since 2011, often resulting in significant damage to property.

A record-breaking glacier outburst flood slammed Alaska’s capital this week. However, for the first time in years, most homes along Juneau’s Mendenhall River were spared.

The water surged out of the suicide basin, a giant pool dammed by the receding Mendenhall Glacier, sending the river to its highest level ever.

New barrier protections

However, two miles of sandbag walls, called Hesco barriers, held back the worst of it. The Army Corps of Engineers installed the walls before the flooding occurred.

In past years, floods have wiped out riverbanks, swept away homes and damaged hundreds more. Officials say that would have been the case again, with nearly 1,000 structures at risk, had it not been for the walls.

“We could have easily had almost 1,000 structures — most of them residences, some multifamily — flooded,” Katie Koester, the Juneau city manager told CBS News. “And for many of those homes, it would have been the second year in a row of flooding. Really cold, icy waters, really difficult to mitigate against, does a lot of damage to your home because of that glacial silt.”

USGS scientists are providing critical data as glacier flooding affects Juneau, Alaska. A glacier acting as a natural dam trapped water that's now releasing, creating flood conditions. Our real-time monitoring supports multi-agency emergency response. https://t.co/cWbaPL45ze pic.twitter.com/4M63vlzSmK

— USGS (@USGS) August 13, 2025

Glacier outburst river surge record

The Wednesday surge caused the Mendenhall River to crest at a record-breaking height of 16.6 feet, according to the National Weather Service. The NWS stated that the height was due to both the surge and the rainfall that occurred days prior to the release…