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A glacier dam bursts and creates minor flooding on the Kenai

  • Author: Lisa Demer
  • Updated: September 27, 2017
  • Published September 25, 2017

Flood waters from the release of the glacially dammed Snow Lake fill the channels and flow under the Snow River bridge Sept. 23, 2017. (Kevin Knotek / AKDOT)

A glacier dam that gave way around Sept. 19 at Snow River on the Kenai Peninsula is causing minor flooding and challenging Kenai River sport fishermen who otherwise could be pulling in one rainbow trout after another.

The National Weather Service has issued a flood warning that it extended on Monday for Kenai Lake and the Kenai River from Cooper Landing to Skilak Lake. It is in effect until 12:30 a.m. Wednesday.

The phenomenon is called a jökulhlaups, an Icelandic term for a flood that suddenly bursts from a glacier.

On the Kenai, water builds up behind Snow Glacier at the headwaters of the Snow River until finally it breaks through, usually every two years, according to the National Weather Service. Melt water flows in tunnels through the glacier until ice plugs give way. The lake drains like a bathtub through the conduits into Snow River and eventually the Kenai.

"What is impressive is the regularity of these things," weather service meteorologist Eric Holloway said in an email. The glacier functions like a dam without man-operated controls.

The flooding is minor, covering boat ramps and some roads. Some driveways, outbuildings and a crawlspace have flooded, National Weather Service hydrologist Crane Johnson said. But the agency doesn't have reports of flooded main houses. Two weather service employees went to the Kenai to assess the situation.

Looking SE over the Snow Glacier, Snow Lake is visible, Sept 19, 2017 before the lake drained.  (Jeff Conaway)
Looking SE over the Snow Glacier, the now-drained Snow Lake is visible, Sept 26, 2017. (Jeff Conaway)

A photo taken Sept. 19 shows the icy lake waters just before release.

The state Department of Transportation closed the road to Primrose Campground, a U.S. Forest Service facility on Primrose Creek at the edge of Kenai Lake, because of flooding.

The Kenai River is running fast and high, making it hard for sport fishermen and their guides to reel in the rainbow trout and Dolly Varden that usually are so abundant in fall, said Andy Wallace, operations manager at Kenai River Drifter's Lodge in Cooper Landing.

"Fishing has been brutal," Wallace said. "It's tough to fish when it's high water. … They are pushed up into the trees."

Guides drift in boats with clients down the river, then row back up. When the river is running more normally, a person can pull in 50 catch-and-release trout a day, he said. But in water that's fast, high and murky, even the guides have been unable to hook fish, he said.

The lodge itself is up high and safe from flooding but boat ramps are under water, he said.

Jim's Landing, off Skilak Lake Road, is a steep dirt ramp that and now the drop off for someone on foot is extreme, Wallace said.

"You go out and you are up to your neck immediately," he said.

The boat landing at Cooper Landing was flooded this past week after the glacial dam on the Snow River burst around Sept 19, 2017. (Photo provided by NWS)

The lodge usually uses the boat ramp at the Sterling Highway bridge across Kenai Lake, the headwaters. The water there was above the rock barriers that protect the banks of the Kenai River from erosion. A boat trailer being backed in was completely underwater, he said.

Snow River itself is no longer flooding. Kenai Lake crested Sunday, and the National Weather Service expects levels to slowly fall this week.

The area from Skilak Lake to Cooper Landing as of Monday remained above minor flood stage as the slug of high water moves through.

At the peak, 16,900 cubic feet of water every second was moving through Cooper Landing, according to the Weather Service.

Typically about 6,000 cubic feet a second move through, said Wallace, who monitors the river levels and flow.

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