Glacial dam releases, triggering evacuation notices for flooding near Juneau

JUNEAU, Alaska (KTUU) - A glacially-dammed basin has released, triggering evacuation notices for residents of Juneau’s Mendenhall Valley, officials say.

Authorities from Juneau and around the state put out the evacuation notice for Alaskans on Tuesday afternoon, saying that floodwaters can be expected to hit homes along the Mendenhall River late Wednesday through Thursday morning.

State officials updated the public on the latest on the expected flooding that in past years left dozens of homes under feet of water in the Mendenhall Valley.

Officials said residents in predetermined areas should be “set” to evacuate, the middle guidance in a “Ready, Set, Go” advisory. That was before Suicide Basin

Any non-emergency concerns and questions can be answered by calling 907 500-0890.

Last year, flooding in the Mendenhall River surged to a record level of 16.65 feet.

City officials didn’t pull any punches on Tuesday.

“If there’s one message that will be reiterated today — please evacuate,” Juneau City Manager Katie Koester said.

“While the HESCO barriers are stronger than they’ve ever been, we really cannot rely on them, and life safety is absolutely the most important thing.”

The barriers have been set up along most of the river’s banks, officials said, in hopes of keeping back the majority of the floodwaters. State officials also said that multiple sump pumps have been set up in various spots along the river to help drain away any water that does reach near homes.

Those within the flood zone of Mendenhall Valley need to finalize last-minute preparations, officials said, as Suicide Basin has reached full capacity.

“The risk is real,” said Ken Murphy, a safety officer with the State of Alaska.

“Debris, erosions, unstable banks, changing water levels and hidden hazards uh make the river dangerous. If you’re near to the river or in the flood zone, you’re in danger. There is no safe reason to approach the water during this event.”

As of 9 a.m. Tuesday, the current elevation of the water was around 1,345 feet, as seen by a USGS laser data on site. The water is starting to overtop the ice dam, according to the National Weather Service in Juneau.

Residents in the inundation area should confirm evacuation plans and prepare a go-bag.

The basin has been releasing annually, causing floods since 2011, the most extreme of which happened in 2025. The City and Borough of Juneau reported 35 homes affected by flooding in 2025, including five homes with 4–5 feet of water in living spaces. The flooding also caused severe erosion and temporary loss of local utilities.

The Mendenhall Lake and River were below normal water levels as of Tuesday morning, most of it due to the lack of rain for most of the summer. The National Weather Service said last year, before the outburst flooding event, the Mendenhall Lake was reporting near nine feet due to effects from an atmospheric river.

The Tuesday press conference was hosted by officials with the National Weather Service, U.S. Army Corp of Engineers, City and Borough of Juneau, U.S. Coast Guard, Central Council of the Tlingit & Haida Indian Tribes of Alaska, and the Alaska Department of Transportation and Public Facilities.

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