For three years in a row, Juneau has had unprecedented flooding in August from a melting glacier. This year, officials built a levee to protect the city. It seems to have helped, but it's temporary.

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. Since 2011, scientists and local officials have kept a close eye on one lake in particular: Suicide Basin,