.png)
How to prepare for this year’s glacial lake outburst flood
- Ellie Ruel
- 34 minutes ago
- 4 min read
As a release from Suicide Basin looms, steps to take and information
By Ellie Ruel
Juneau Independent
The annual glacial lake outburst flood is expected within the next two weeks as the water level in Suicide Basin nears overtopping. Below are resources and information to prepare.
Local scientists estimate this year’s release will result in a similar magnitude of flood to last year due to competing changes in basin capacity. As of Wednesday evening, Suicide Basin’s water level is at about 1,340 feet. According to the National Weather Service Juneau, the basin will start overflowing once the water level reaches 1,350 feet. It’s also possible for the basin to release before it reaches full capacity.
Past subglacial releases have started one to six days after the basin fills. Mendenhall River’s flood stage usually peaks within a day or two, depending on conditions and release rate.
To stay informed on current conditions, residents can sign up for emergency alerts to receive texts and calls about flood risk.
The City and Borough of Juneau advises impacted residents to evacuate once the ice dam breaks and the release starts. The National Weather Service will send out a flood warning, and in-person evacuation notices will be given to neighborhoods within the possible inundation area. Newly updated evacuation maps include 1,900 Mendenhall Valley homes, nearly double the number from previous maps, to account for possible road blockages in the event of a HESCO breach.
If there is a HESCO breach, the National Weather Service will issue a flash flood warning advising those in the area to shelter in place. First responders will be staged on both banks of the Mendenhall River.
Evacuation routes from CBJ are linked below, mapped to prevent traffic congestion.
Evacuation routes by area
Residents north of Division Street, please travel north on Riverside Drive, toward Mendenhall (Back) Loop Road and out of the inundation area.
Residents south of Division Street, travel south on Riverside Drive, turn left on Stephen Richards Memorial Drive, towards Mendenhall Loop Road.
On Rivercourt Way, travel south on Riverside Drive, toward Egan Drive
On the west side of the Mendenhall River, travel west on Mendenhall (Back) Loop Road toward Auke Bay (avoid Back Loop Bridge).
West of Brotherhood Bridge, travel west on Glacier Highway toward Auke Bay
The Alaska Department of Transportation and Public Facilities will close the Back Loop Bridge to all traffic and the Brotherhood Bridge to foot traffic during the flood, beginning when the Mendenhall Lake gauge reaches 12 feet.
“Do not attempt to drive or walk on flooded roads or approach closed bridges,” DOT’s webpage states. “Floodwater moves fast and conditions can change without warning.”
An emergency shelter will be operated by the American Red Cross at the Floyd Dryden Gymnasium, and extra vehicle parking is available at various locations through this registration link.
For those evacuating with pets, limited spaces are available at the Red Cross shelter. Juneau Animal Rescue offers emergency pet sheltering and an emergency pet planning brochure.
Before evacuating, the city recommends residents pack a go bag with medications, food, water, essential documents and, if needed, pet supplies. If possible, it’s also recommended to move valuables to higher locations in homes and dispose of or secure household hazards.
Sandbags are available at the Dimond Park Field House via drive-through every Saturday until the flood, and supplies to personally fill sandbags are available all week. A video by the Juneau Flood Solution Advocates shows how to manually fill a sandbag. As of Wednesday, the city announced sandbags will be hand-filled until repairs are made to the sandbag-filling machine.
Pumps will be running along HESCO barriers to minimize damage from seepage.
Sandbag distribution events in front of the field house are scheduled for Thursday from 4 to 6 p.m. and on Saturday from 11 a.m. to 3 p.m. if the basin has not released.
During the flood, people are advised to stay clear of the river and barriers. Updates on river conditions can be found through the Juneau Flood Solutions Advocates Eyes on the River livestream.
“We’re thankful to have the flood barrier system in place to protect Juneau residents from the flood. But while they’re effective, the barriers are not perfect – water can seep through, and flooding due to tree strikes is possible,” a CBJ social media post states. “For your safety, and for the safety of first responders, please stay away from the barriers.”
For additional information, CBJ has set up a flood hotline at 907-500-0890, operating Monday through Friday from 9 a.m. to 4 p.m. Once the release begins, it will switch to 24-hour operation. Residents can also contact floodresponse@juneau.gov or view the city’s guide to flood preparedness.
• Contact Ellie Ruel at ellie.ruel@juneauindependent.com.
