Mendenhall flood waters begin to recede

Montana Creek road was closed just past Arctic Circle. (Photo by Heather Bryant/KTOO)

A family of ducks swim around Skater's Cabin Road just past the Mendenhall Campground Road. (Photo by Heather Bryant/KTOO)

Much of the area around the bear viewing platform was under at least two feet of water this evening. This porcupine headed up a tree across from the platforms. (Photo by Heather Bryant/KTOO)

Water covered most of the trails around the glacier today. The area around the pavilion has been closed since yesterday. (Photo by Heather Bryant/KTOO)

The Juneau Police Department placed officers at each end of the bridge on Back Loop Road to keep people from gathering on the bridge during heavy traffic. (Photo by Heather Bryant/KTOO)

Montana Creek road was closed just past Arctic Circle. (Photo by Heather Bryant/KTOO)

A family of ducks swim around Skater’s Cabin Road just past the Mendenhall Campground Road. (Photo by Heather Bryant/KTOO)

Much of the area around the bear viewing platform was under at least two feet of water this evening. This porcupine headed up a tree across from the platforms. (Photo by Heather Bryant/KTOO)

Water covered most of the trails around the glacier today. The area around the pavilion has been closed since yesterday. (Photo by Heather Bryant/KTOO)

The Juneau Police Department placed officers at each end of the bridge on Back Loop Road to keep people from gathering on the bridge during heavy traffic. (Photo by Heather Bryant/KTOO)

Flood waters have begun to recede on Mendenhall Lake and the Mendenhall River.

The National Weather Service reports the lake crested at a record height of 11.8 feet around 4:30 p.m. Friday. The previous record of 11.2 feet was set in 1995.

“The rain is adding a little bit of water to the lake and the river, but it is a very minor player in what’s going on right now,” says Brian Bezenek, lead forecaster at the Juneau office.

The old record was likely set by heavy rain, Bezenek says, unlike the new one.

This week’s flooding was caused by a glacial outburst flood, also called a jökulhlaup. The last occurrence in the Mendenhall Valley was in 2012. The Mendenhall Glacier acts as a temporary dam in front of Suicide Basin, where water gradually accumulates. Water pressure and other factors eventually overcome the dam and the basin drains into the lake and river.

The Mendenhall River crested at 13.5 feet. Both crests fit under the weather service definition of moderate flooding.

“But the water should be falling rapidly through the evening and overnight,” Bezenek says.

No waves were visible on the lake Friday evening. A family of ducks swam down Skater’s Cabin Road as Forest Service officials blocked off the flooded roadway.

The flood warning remains in effect through 10 p.m. Saturday. City officials are asking people not to stop or stand on bridges to take photographs. They also say the banks of the Mendenhall River may be unstable and should be avoided.

View Drive remains closed, though barricades along Riverside Drive from Rivercourt Drive to Killewich Avenue are being removed. Alaska Electric Light & Power anticipates restoring power to View Drive and the Mendenhall Lake campground Saturday morning.

Bezenek says he thinks it will be business as usual in the area come Sunday.

Heather Bryant contributed to this report.

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