Each year since 2011, flooding from Suicide Basin, a glacier-dammed lake along Mendenhall Glacier, has impacted residents in the highly populated Mendenhall Valley in Juneau. AK CASC scientists at the University of Alaska Southeast have worked with local partners including the National Weather Service and the US Geological Survey for several years, monitoring the basin to better understand and predict flooding events. As ice dynamics in the basin evolve, the timing, magnitude, and mechanism of drainage from the basin can change dramatically year-to-year. Learn about how the basin formed, what goes on during drainage events, and how researchers at the AK CASC and partner organizations monitor conditions throughout the summer in our new glacial lake outburst flood story map.

In 2020, water from Suicide Basin overtopped the Mendenhall Glacier ice dam for 5-6 days before beginning to drain beneath the glacier on July 30th. The resulting 6-foot rise in water at Mendenhall Lake was the third-highest crest on record, peaking at 11.53 feet in the early morning of August 1st. The highest recorded crest, 12 feet, occurred during the 2016 outburst flood. This year, the flooding covered some roads and residential yards along Mendenhall River and caused the closure of the Mendenhall Lake campground.

Throughout August, continued drainage from Suicide Basin and heavy rainfall caused several more flooding events that inundated areas surrounding Mendenhall Lake and River. Researchers from AK CASC and USGS made multiple visits to the basin to survey the water level.

For the latest information on conditions in Suicide Basin, visit the National Weather Service page.

Hidden Water: The Suicide Basin Outburst Flood