Suicide Basin, an ice-dammed lake on an arm of Mendenhall Glacier, has filled up with meltwater and sent destructive surges of water into Juneau for 3 straight summers.

Alaska Gov. Mike Dunleavy declared a state disaster due to the "imminent threat of catastrophic flooding from a glacier lake outburst flood" in the Juneau area.

The declaration from Dunleavy came after the City and Borough of Juneau and the Central Council of the Tlingit and Haida Indian Tribes of Alaska declared their own, preemptive disaster declaration ahead of the glacial outburst flood on Friday, as first reported by KTOO.

A historic flood is unfolding in Juneau, Alaska, as massive water releases from Suicide Basin threaten to break all previous records. With the Mendenhall River at risk of overflowing, officials have issued urgent evacuation notices and closed key city facilities.

This year, a giant wall of reinforced sandbags erected with the help of the U.S. Army Corps of Engineers held back the worst of the flooding in Juneau, to residents' great relief.

The all clear has been given and residents have been allowed to return to their homes in Alaska’s capital of Juneau after a glacial lake outburst sent debris-filled water rushing down the Mendenhall River on Tuesday night and Wednesday morning.

Communities in Alaska have issued flood warnings and evacuations as the glacial release from Suicide Basin above Mendenhall Lake has begun.