By SUZANNE DOWNING
Aug. 11, 2026 – Suicide Basin above Juneau’s Mendenhall Valley is full and beginning to overtop the ice dam, prompting officials to warn residents in the potential flood zone to finalize preparations and be ready to evacuate.
The basin is expected to begin releasing within one to six days, according to an alert issued Tuesday by the City and Borough of Juneau. Once the release begins, water will drain beneath the Mendenhall Glacier into Mendenhall Lake and River, potentially producing another glacial lake outburst flood.
Residents within the designated inundation area are being advised to confirm their evacuation plans, prepare go-bags and complete any remaining work needed to protect their homes and property.
The National Weather Service in Juneau reported Tuesday that the basin’s water elevation had reached approximately 1,345 feet and that water was beginning to flow over the ice dam. Monitoring cameras, laser equipment and U.S. Geological Survey instruments are operating.
A calving event occurred inside the basin on Saturday, Aug. 8, causing a shift in some of the laser-gauge readings. Weather officials said they are aware of the change and continue to monitor conditions.
One potentially favorable factor is that Mendenhall Lake and River are currently below normal levels. The lake gauge was near four feet Tuesday. By comparison, the lake was already near nine feet—minor flood stage—before the record August 2025 outburst because of heavy rainfall from an atmospheric river.
The magnitude and timing of a glacial lake outburst depend on how quickly the basin drains, the volume of stored water, rainfall and conditions downstream.
Juneau has endured increasingly serious flooding from Suicide Basin in recent years. The Aug. 13, 2025 event pushed Mendenhall Lake to a record 16.65 feet and caused major flooding in the valley. The recurring threat has led to extensive sandbagging, temporary barriers and other flood-protection work this summer.
The city, the National Weather Service and other local agencies are monitoring the basin. Another emergency alert will be issued when officials confirm that the release has begun.
Residents can review the evacuation advisory map and preparation guidance at Juneau Flood Ready. Live basin information and forecasts are available through the National Weather Service Suicide Basin monitoring page.
People can register for emergency notifications at CBJ Alerts or by texting CBJ to 38276. Updates will also be posted through the CBJ newsroom and the city’s Facebook page.
Home » Suicide Basin is full; Juneau residents warned release could begin within days
Suicide Basin is full; Juneau residents warned release could begin within days
By SUZANNE DOWNING
Aug. 11, 2026 – Suicide Basin above Juneau’s Mendenhall Valley is full and beginning to overtop the ice dam, prompting officials to warn residents in the potential flood zone to finalize preparations and be ready to evacuate.
The basin is expected to begin releasing within one to six days, according to an alert issued Tuesday by the City and Borough of Juneau. Once the release begins, water will drain beneath the Mendenhall Glacier into Mendenhall Lake and River, potentially producing another glacial lake outburst flood.
Residents within the designated inundation area are being advised to confirm their evacuation plans, prepare go-bags and complete any remaining work needed to protect their homes and property.
The National Weather Service in Juneau reported Tuesday that the basin’s water elevation had reached approximately 1,345 feet and that water was beginning to flow over the ice dam. Monitoring cameras, laser equipment and U.S. Geological Survey instruments are operating.
A calving event occurred inside the basin on Saturday, Aug. 8, causing a shift in some of the laser-gauge readings. Weather officials said they are aware of the change and continue to monitor conditions.
One potentially favorable factor is that Mendenhall Lake and River are currently below normal levels. The lake gauge was near four feet Tuesday. By comparison, the lake was already near nine feet—minor flood stage—before the record August 2025 outburst because of heavy rainfall from an atmospheric river.
The magnitude and timing of a glacial lake outburst depend on how quickly the basin drains, the volume of stored water, rainfall and conditions downstream.
Juneau has endured increasingly serious flooding from Suicide Basin in recent years. The Aug. 13, 2025 event pushed Mendenhall Lake to a record 16.65 feet and caused major flooding in the valley. The recurring threat has led to extensive sandbagging, temporary barriers and other flood-protection work this summer.
The city, the National Weather Service and other local agencies are monitoring the basin. Another emergency alert will be issued when officials confirm that the release has begun.
Residents can review the evacuation advisory map and preparation guidance at Juneau Flood Ready. Live basin information and forecasts are available through the National Weather Service Suicide Basin monitoring page.
People can register for emergency notifications at CBJ Alerts or by texting CBJ to 38276. Updates will also be posted through the CBJ newsroom and the city’s Facebook page.
Suicide Basin nearing capacity as Juneau’s Mendenhall Valley braces for another flood
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