Each summer in the mountains above Juneau, Alaska, meltwater from the massive Mendenhall Glacier flows into mountain lakes and into the Mendenhall River, which runs through town.

One of Alaska's most populated cities is bracing for potentially catastrophic flooding as a basin dammed within the Mendenhall Glacier has started to release water.

A wave of water that gushed out of an Alaskan glacial lake and sent a river surging to a new record level is causing flooding issues in the state capital of Juneau for the third consecutive August.