Alaska declares catastrophic flooding declaration threat from glacial lake outburst
Alaska Governor Mike Dunleavy has taken proactive measures by issuing a disaster declaration in response to the imminent threat of catastrophic flooding from a glacial lake outburst flood (GLOF) linked to Suicide Basin, a side basin of the Mendenhall Glacier. This declaration follows a joint local disaster declaration by the City and Borough of Juneau and the Central Council of the Tlingit and Haida Indian Tribes of Alaska.
The volume of water in Suicide Basin has reached levels seen during previous flood events, indicating an imminent release that could impact the Mendenhall River and surrounding neighborhoods in the Mendenhall Valley. This year’s conditions follow two consecutive years of severe flooding, with the August 2024 GLOF causing widespread damage to homes, public infrastructure, and utilities.
Governor Dunleavy emphasized the importance of acting early to reduce impacts and preserve community safety. By issuing the disaster declaration before the flood occurs, state resources and personnel can be positioned in advance to support local and tribal governments in their efforts to protect lives, homes, and essential services.
The Alaska State Emergency Operations Center has been activated to support local and tribal efforts, including interagency coordination, emergency permitting, public messaging, and preparations for protective actions and potential response. City Manager Katie Koester stated that they are prepared for any scenario, with HESCO barriers in place and a proactive emergency declaration giving them the tools to act swiftly and decisively.
The National Weather Service (NWS) reported that Suicide Basin is at full capacity and showing signs of over-topping the ice dam, with icebergs being pulled towards the overflow channel. The NWS advised residents to finish flood preparation and planning, as the basin is expected to release soon.
City officials in Juneau have sent out alerts via Wireless Emergency Alert and Emergency Alert Systems, notifying residents of the impending flood. Evacuation preparation notices are being distributed to homes within the inundation zone to ensure residents are prepared for potential flooding.
A glacial lake outburst flood (GLOF) occurs when a glacial lake reaches its breaking point, releasing water downstream and causing flooding. These events are unpredictable and have caused significant loss of life and infrastructure worldwide. As temperatures rise and glaciers continue to melt, the risk of GLOFs may increase, highlighting the importance of proactive measures and preparedness in at-risk areas like Juneau.
