Forecasters estimate 14.6 billion gallons of water were released during last year's flood, enough to fill more than 22,000 Olympic-sized swimming pools, according to the weather service. Previous years floods have swamped basements, destroyed infrastructure and collapsed buildings near the riverbanks.
A glacial outburst like this occurs when an ice dam holding back a lake - in this case Suicide Basin - collapses from the summer heat, releasing the water in a short period of time. Suicide Basin is part of the Mendenhall Glacier, a popular tourist destination easily reached from Juneau.
Federal scientists say climate change is causing the glacier to melt faster, along with altering rainfall patterns, exacerbating the danger. The
first recorded outburst flood from the glacier happened 2011, according to the National Weather Service.