Juneau, the capital city of Alaska, experienced a catastrophic glacial lake outburst flood (GLOF) on August 13, 2025, as meltwater from Suicide Basin—an ice-dammed lake within the Mendenhall Glacier—was suddenly released, sending torrents of water downstream into the Mendenhall River. The floodwaters surged to a record-breaking height of 16.65 feet, surpassing previous records set in 2023 and 2024.
The event forced evacuations across several neighborhoods, flooded streets, and damaged infrastructure. While newly installed flood barriers—known as HESCO barriers—helped prevent widespread destruction, some homes and roads still experienced seepage and water damage.
Scientists from the University of Alaska Southeast have been monitoring the glacier for years, noting that warming temperatures have caused the Mendenhall Glacier to retreat, leaving behind a basin that fills with rainwater and snowmelt each summer. When pressure builds, the water escapes beneath the glacier, triggering these increasingly frequent and severe floods.
Local officials issued emergency alerts and evacuation orders, urging residents to avoid flooded areas and prepare for future events. Despite the scale of the flooding, no major injuries or rescues were reported, thanks to early warnings and community preparedness.
The incident underscores the growing impact of climate change on glacial systems and urban safety. Authorities are now considering long-term mitigation strategies, including diversion infrastructure and reinforced levees, to protect Juneau from future glacial outbursts.
