Glacial lake outburst flood in Juneau
Last modified: August 10, 2026 17:08:49
A glacial lake outburst flood affecting areas along the Mendenhall River in Juneau is forecast for mid-August 2026. The University of Alaska Southeast Juneau campus, including campus housing, is not located in the flood evacuation zone. No direct impacts to campus are anticipated.
The University of Alaska Southeast is prepared to support Juneau-based University of Alaska students and employees who may be impacted. Resources, including temporary housing, parking, drying equipment, counseling and more, are available:
University of Alaska students: Contact Dean of Students Damian Medina to connect with services and resources, ask questions, or relay concerns.
University of Alaska employees: Visit the UAS Employee Hub for the latest information and to reserve access to flood response services and resources. If you are unable to access the Employee Hub or have any questions or concerns, please contact the UAS Incident Management Team at uas.incidentmanagement@alaska.edu or your supervisor.
CBJ Guide to Flood Preparedness: Sign up for emergency alerts, view the evacuation advisory map, find out how to prepare, and access public flood response resources including a flood information hotline. From the City and Borough of Juneau.
Juneau Glacial Flood Dashboard: Find flood maps, forecasting, FAQs and historical data. Maintained by UAS in collaboration with the Alaska Climate Adaptation Center.Since 2011, a side basin of the Mendenhall Glacier, known as Suicide Basin or Kʼóox Ḵaadí Basin, has periodically filled with water and then rapidly drained out beneath the glacier. The flood inundates areas around Mendenhall Lake and the Mendenhall River, and has increased over time. In 2025, HESCO barriers were placed around the river, which reduced impacts to surrounding neighborhoods.
See the StoryMap Glacier Outburst Floods: Mendenhall Glacier for a visual explanation of this phenomenon. UAS scientists are at the forefront of researching and sharing findings about glacial lake outburst floods in Alaska.
Flooding timeline: What to expect
Basin is full: When the National Weather Service determines that the basin is full, the City and Borough of Juneau and partners will issue an evacuation advisory via SMS text. A full basin means that the main release event will likely begin in 1 to 6 days.
Basin is releasing: When the basin release begins, the National Weather Service will issue a flood warning. An evacuation advisory and notices will be pushed out through multiple channels. The floodwaters in Mendenhall Lake and the Mendenhall River typically crest 24-48 hours after the main basin release begins.
Water has receded: When it is safe to return to the evacuation zone, the City and Borough of Juneau and partners will issue notice via SMS text.
Seasonal timing: Juneau’s glacial outburst floods have occurred between June and October, with major events usually taking place in July or August. It is not uncommon to have multiple floods in a year, with a major summer event followed by one or more smaller floods in the fall.