Juneau’s latest glacial outburst flood was lower than predicted and caused minimal damage

Water rushes in the Mendenhall River on Sunday, Oct. 20, 2024. (Clarise Larson/KTOO)

Water levels on Juneau’s Mendenhall Lake and River are returning to normal following a moderate glacial outburst flood that peaked at 10.7 feet at 11:30 p.m. Sunday night.

City Emergency Programs Manager Tom Mattice said no damage had been reported since the National Weather Service Juneau canceled the flood warning early Monday morning. He said cold temperatures ultimately helped keep flooding minimal.

“We feel fortunate on many fronts, and we’re just going to continue our research on the basin and try and prepare the best we can for the next one,” Mattice said.

The Weather Service issued a flood warning on Saturday morning as water levels dropped in Suicide Basin, a glacial lake behind the Mendenhall Glacier that drains periodically, sending rain and meltwater downstream into the lake and river.

This weekend’s flooding reached only a moderate flood stage, as opposed to August’s record-breaking outburst flood that damaged nearly 300 homes in the Mendenhall Valley.

The water level ended up being lower than expected this time around, thought the Mendenhall Campground and Skater’s Cabin saw the usual flooding. Even at a moderate stage, water was also expected to reach yards on View Drive. But Mattice said that didn’t happen this time.

“We had View Drive ready for closures, but no water actually came up to that level,” he said. “So we got very, very lucky. The upper river corridor carried a little more water than usual, and kept that to a minimum.”

This latest release was anticipated and residents were warned ahead of time. The city distributed thousands of sandbags to residents of flood-impacted neighborhoods over the weekend. That distribution has now ended with more than 130 households receiving sandbags.

The city also tested out a new emergency alert system for the first time. Residents can sign up for text or email notifications on the city website. It also allows the city to auto-dial residents in

“We’re still ironing out the bugs, but that’s the first time we put it to the test,” Mattice said.

Earlier this month, the city announced plans to work with the U.S. Army Corps of Engineers to install flood protection barriers along four miles of Mendenhall River’s bank in the coming months.

Funding for that project will be discussed at a Juneau Assembly meeting Monday evening.

With freezing temperatures settling in, local officials don’t expect any more outburst flooding this year or through the winter.

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