Jökulhlaup raises Taku River levels; Suicide Basin release likely in next few weeks

Aerial view of the Taku River basin.
Aerial view of the Taku River basin. (Creative Commons photo by Lee LeFever)

(Update Tuesday 5 a.m. – National Weather Service says Taku River crested at 8 p.m. Monday at 40.4 feet. As of 5 a.m. Tuesday, the river level was 37.42 feet.)

Water levels on the Taku River east of Juneau are rising after an apparent glacial dam release, or jökulhlaup, within the last several days.

The Taku River is expected to crest Tuesday morning at 42 feet, just under minor flood stage.

Nicole Ferrin, a meteorologist with the National Weather Service in Juneau, asks boaters to use caution. The rising water level will bring more debris and much colder water.

“Quite a lot colder than usual,” Ferrin said. “So, if you were to perhaps fall in the river, there would be more risk of hypothermia.”

Ferrin said the glacial dam release occurred on a lake that drains under the Tulsequah Glacier on the Canadian side of the border. There are no observation stations around that glacier, so the weather service is asking local pilots to report any signs of change in the area.

Meanwhile, the weather service is also monitoring water levels in Suicide Basin on the eastern edge of Mendenhall Glacier.

The basin regularly becomes a glacially-dammed lake. When the dam gives way, it could send as much as 20,000 cubic feet of water each second under the glacier and potentially flood Mendenhall Lake and Mendenhall River.

“We usually see the worst conditions near the campground where some of the campsites can get flooded, and — for larger events — the roadway down by Skaters Cabin and anyone who lives along the river,” Ferrin said.

Ferrin said they estimate Suicide Basin may release in the next week or two.

Ferrin said the weather service has a new web page that includes web cam views of Suicide Basin, a time lapse of it filling up and a chart comparing current water levels to past years. There’s also link to an interactive inundation map for the area where Juneau residents can determine how their property might be affected by a rising Mendenhall River level.

Suicide Basin, June 24, 2019.
Suicide Basin, June 24, 2019. (U.S. Geological Survey webcam photo)
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