An eroding riverbank is seen on Tuesday morning, Sept. 16, 2025, as the Mendenhall River recedes after a glacial outburst flood. (Photo by James Brooks/Alaska Beacon)
A glacier-caused flood in Alaska’s capital city on Monday was weaker than forecasted, according to measurements taken by the National Weather Service and U.S. Geological Survey.
The flood on Juneau’s Mendenhall River topped out at 9.6 feet at 7:30 p.m. Monday evening. No significant damage was reported.
Forecasters had been expecting a flood of between 11 and 12 feet to reach its full height early Tuesday morning.
The Mendenhall River’s normal level is between 3 and 4 feet.
Since 2011, Juneau’s Mendenhall River has experienced regular glacial outburst floods each summer and fall as Suicide Basin, an ice-locked lake, fills with rain and meltwater, overtopping an ice dam.
Last year, a flood damaged hundreds of homes in the Mendenhall Valley. Over the winter, city officials constructed a semipermanent levee of HESCO barriers along the river to protect homes, and a record-setting 16.65-foot flood this summer was mostly held at bay.
After that event, city officials reinforced the levee and stationed additional de-watering pumps.
More work is expected before next summer, when further floods are expected.
Colder weather has already begun to arrive in Juneau’s nearby mountains, reducing the rate of glacial melt and limiting the odds of another major flood this year.
