Juneau officials are asking residents in the Mendenhall Valley’s glacial outburst flood zone to evacuate ahead of this year’s flood, currently forecast for Aug. 8.
The flood will be the first test of a temporary levee the city installed this spring. Although city officials said they expect it will protect residents, they want everyone in the flood zone to evacuate anyway.
Suicide Basin is almost full and the National Weather Service predicts it could soon unleash a torrent down the Mendenhall River. As the flood approaches, the community is preparing for the worst-case scenario.
The levee that was installed to protect most neighborhoods in the valley is made up of HESCO barriers — large metal baskets lined with fabric and filled with sand, which are stacked in backyards along the river.
Ryan O’Shaughnessy is Juneau’s emergency manager. He said an analysis the city commissioned from engineering firm Michael Baker International shows that the levee should hold back floodwaters properly.
But he said people shouldn’t bet their lives on that.
“We’re extremely confident in the HESCO barriers,” O’Shaughnessy said. “We’re still recommending that people evacuate. You just cannot be too careful with life and, you know, the potential for death or injury.”
If the levee fails, O’Shaughnessy said it would trigger a flash flood and people wouldn’t have much time to escape.
“It will be difficult to extract anyone in a search and rescue operation with water moving that swiftly,” he said.
So he recommends that Valley residents pack go-bags in advance and arrange to stay with friends or family in areas outside the flood zone.
The city and U.S. Geological Survey plan to watch how the levee performs during the flood using drones and other cameras. O’Shaughnessy said the city will bolster the levee with large sandbags called supersacks if they see extreme bank erosion.
“Where there are those bends in the river, where we’ve historically seen that kind of activity, are the places that we’re prepared to respond to it,” he said.
Those bends include the corner of Riverside Drive and Killewich Drive, along Meander Way and near Dimond Park.
Evacuation Timeline
The city plans to issue an evacuation warning as soon as the remote camera in Suicide Basin shows the water is draining out — that’s the same time that the National Weather Service will issue a flood warning.
The evacuation notice will buzz on cell phones located in the Juneau area through a federal alert system. But to ensure you receive a warning — even if you’re not in the area at the time — O’Shaughnessy said residents should sign up for the city’s alert system.
From the moment the evacuation warning is issued, valley residents will have an estimated 36 hours to get out of the flood zone before floodwaters reach the river.
City officials will publish a map of the flood zone when the National Weather Service issues a forecasted flood height. Forecast updates are likely to come about a day later. Residents can also see if their home is in the flood zone by plugging the forecasted height into the interactive map at juneauflood.com and toggling “HESCO Barriers OFF.”
Floyd Dryden will serve as an emergency shelter during the flood. Its gymnasium can hold around 50 cots. Folks with RVs will be able to park in the lot and there will also be an area where people can pitch tents outside.
Britt Tonnessen is the community disaster program manager for the Red Cross of Alaska in Southeast. She said the shelter will be available for as long as Valley residents need it.
“If it happens during the day and the flood clears out, maybe it’s just an evacuation point,” Tonnessen said. “If it happens in the night, it could be a sheltering situation.”
People who stay at the shelter can expect a cot, food and access to information and services. Tonnessen said that the Red Cross is prepared to assist elders and those with disabilities and medical needs.
“If people are separated from medication, durable medical equipment — we have disaster health services volunteers, and they try to more immediately reconnect those people with those services,” she said.
Ahead of the flood, Tonnessen is still accepting volunteers and said that those interested can sign up on the Red Cross website.
In a Facebook survey, Valley residents affected by the floods said they need help filling sandbags and setting them up on their properties.
The city, the Central Council of the Tlingit & Haida Indian Tribes of Alaska and volunteers with United Way will be handing out free sandbags at the Dimond Park field house this Saturday and July 26 from 11 a.m. to 3 p.m.
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