Preemptive disaster declaration issued for Juneau region as Suicide Basin overtops near Mendenhall Glacier, Alaska
Suicide Basin above Mendenhall Glacier in Juneau, Alaska, began overtopping its ice dam at about 19:00 LT on August 10, 2025, triggering a unified emergency response and a state disaster declaration the same day ahead of an expected glacial lake outburst flood (GLOF).
Suicide Basin, Alaska at 06:01 local time on August 12, 2025. Credit: USGS
Suicide Basin, a glacier-dammed lake adjacent to Mendenhall Glacier in Juneau, reached capacity and began spilling over its ice dam on Sunday, August 10, according to the City and Borough of Juneau (CBJ) and the National Weather Service (NWS).
The National Weather Service (NWS) said in a 07:00 LT update on Tuesday, August 12 that the Mendenhall River was elevated and in Minor Flood Stage due to moderate to heavy rainfall over the previous three days. The river was expected to crest through Tuesday morning, then fall below flood stage by Tuesday afternoon and into Wednesday as drier conditions return.
At the time of the update, the basin’s water surface was at 411 m (1 348 feet).
“At this time, there is no indication of a basin release from Suicide Basin. The basin is overtopping and slowly eroding the overflow channel, which is lowering water levels slowly. Please check back for more updates,” the NWS said.
In past years, the main release has started up to 6 days after the basin reached full capacity and began overtopping, which in this case started on Sunday, August 10.
Live view of Suicide Basin and Mendenhall Glacier
Real-time USGS Images – Updates from Spring to Fall
Disaster declaration issued in response to imminent glacial flood threat in Juneau
The incident prompted activation of a Unified Command involving CBJ, Central Council of Tlingit & Haida Indian Tribes of Alaska, U.S. Coast Guard Sector Southeast Alaska, the Alaska Division of Homeland Security and Emergency Management (DHSEM), and federal partners.
Wireless Emergency Alerts were issued through the Integrated Public Alert and Warning System (IPAWS), advising residents in low-lying areas of the Mendenhall Valley to prepare for evacuation.
On August 10, Governor Mike Dunleavy issued a state disaster declaration to expedite resource deployment and financial assistance. The order followed local disaster declarations issued on August 8 by CBJ and Tlingit & Haida.
Flood mitigation measures include deployment of more than 10 000 HESCO barriers designed to protect over 460 properties. However, it’s important to note that the barriers have not yet been tested against a full-scale outburst flood.
An evacuation shelter has been established at Floyd Dryden Middle School, with transportation and staging areas prepared to assist residents.
Suicide Basin is a side basin of the Mendenhall Glacier above Juneau, Alaska. Since 2011, it has released glacier lake outburst floods that cause inundation along Mendenhall Lake and River annually with a record major flood event taking place on August 6, 2024. The latest release took place on October 20, 2024.
The 2023 and 2024 floods were the largest on record, with the 2024 event damaging nearly 300 residences and significantly altering the Mendenhall River channel.
The USGSand local scientists estimate that the hazard from Suicide Basin will persist for 25–60 years as the Mendenhall Glacier continues to retreat.
Public access to the Nugget Falls Trail was closed on August 11, and additional restrictions near Mendenhall Lake are being implemented. Officials urge residents to monitor official updates and remain ready to evacuate should conditions deteriorate rapidly.
I'm a dedicated researcher, journalist, and editor at The Watchers. With over 20 years of experience in the media industry, I specialize in hard science news, focusing on extreme weather, seismic and volcanic activity, space weather, and astronomy, including near-Earth objects and planetary defense strategies. You can reach me at teo /at/ watchers.news.
Commenting rules and guidelines
We value the thoughts and opinions of our readers and welcome healthy discussions on our website. In order to maintain a respectful and positive community, we ask that all commenters follow these rules.