Emergency Declared in Alaska as Glacier Basin Nears Record Flood Release
Authorities in Alaska’s capital are bracing for what could be one of the largest glacial lake outburst floods on record, triggering state, local, and tribal disaster declarations before the waters even begin to surge.
On Sunday, Governor Mike Dunleavy issued a statewide disaster declaration in anticipation of a potentially catastrophic release from Suicide Basin — a glacial side basin perched above the Mendenhall Glacier. The move follows earlier declarations from the City and Borough of Juneau and the Central Council of the Tlingit and Haida Indian Tribes of Alaska.
Hydrologists with the National Weather Service (NWS) and U.S. Geological Survey (USGS) have confirmed that Suicide Basin is now holding water volumes equal to or greater than those measured during the worst flooding events on record. The ice-dammed basin has already begun to overtop, with icebergs drifting toward an overflow channel — an ominous sign that floodwaters could soon pour into the Mendenhall River and surrounding neighborhoods.
“This year is different. We’re not just responding — we’re ready,” Juneau City Manager Katie Koester said. “The HESCO barriers are in place, and we believe they will perform as designed, but our job is to plan for every scenario — especially in the face of what could be another historic flood event.”
The August 2024 glacial lake outburst flood (GLOF) devastated parts of the Mendenhall Valley, damaging homes, public infrastructure, and utilities. That disaster led to both state and federal emergency declarations. Officials say the proactive approach this year will allow state resources and personnel to be pre-positioned.
The NWS warned that in past years, overtopping has preceded major flooding by as much as six days. On Sunday, August 10, instruments began detecting slow drops in basin water levels — another sign the release could be imminent.
Residents have been urged to finalize flood preparations immediately. Emergency alerts have been sent to cell phones throughout Juneau, and printed evacuation preparation notices are being distributed to every home within the 17-foot inundation zone. A second alert will be issued when water begins its rapid descent from the basin.
Governor Dunleavy underscored the importance of acting early: “By issuing this declaration before the flood occurs, we can position resources in advance to reduce impacts and preserve community safety.”
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