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Mendenhall Lake and River flood following burst glacial ice dam, water begins to recedes during the afternoon
Published: 07/21/2011 09:24:55
Updated: 07/21/2011 13:43:41

VIDEO: Mendenhall Lake and River flooding on the morning of July 21st, 2011 (Image: Mikko Wilson / KATH-TV)

VIDEO: Aaron Jacobs of the National Weather Service talks about the Mendenhall flooding at 8:22am 7/21/11 (Image: Mikko Wilson / KATH-TV)

A river gauge shows the rapid rise in the Mendenhall River (NWS/USGS)

The Mendenhall River flooding at Mendenhall Loop Road bridge at 6:37am July 21st 2011 (Mikko Wilson / KATH-TV)

The Mendenhall Lake flooding at Skater's Cabin at 5:35am July 21st 2011 (Mikko Wilson / KATH-TV)

The Mendenhall Lake flooding closes the road at Skater's Cabin (Photo 7:13am) July 21st 2011 (Mikko Wilson / KATH-TV)

A house on View Drive is flooded by the Mendenhall River Thursday morning (Mikko Wilson / KATH-TV)

Flood waters of the Mendenhall River creep towards a house at the end of View Drive Thursday morning (Mikko Wilson / KATH-TV)

Water gushes out of the Mendenhall Glacier as an ice dam higher up the glacier bursts Thursday morning (Mikko Wilson / KATH-TV)

Officials measure 1.5 feet deep water on the West Glacier Trail road before closing the area (Mikko Wilson / KATH-TV)

The Mendenhall Lake floods the Mendenhall Campground Thursday morning (Mikko Wilson / KATH-TV)

The Mendenhall River flooding at Mendehall Loop Road bridge at 6:32am July 21st 2011 (Mikko Wilson / KATH-TV)

The National Weather Service issued a Flood Warning for the Mendenhall Lake and Mendenhall river early Thursday morning, following a rapid increase water level after a glacial lake above the Mendenhall Glacier bust Tuesday morning, sending millions of gallons of additional water into the lake every minute.

Officials closed the following areas:
- The Mendenhall Campground (evacuated).
- The West Glacier Trail road.
- The Brotherhood Bridge (Kaxdigoowu Heen Dei) trail.

Officials are also asked people to stay away from the river, especially:
- View Drive. Suggested evacuation.
- The banks of the river. They have become unstable.
- Bridges over the river. Don't stop to take photos.
- The Dredge Lake area. Also heavily flooded.

The ice forming a glacial lake, believed to be at the base of Mt. McGinnis above the Mendenhall Glacier, gave way Tuesday morning starting the flow of water into the Mendenhall Lake and then into the Mendenhall River. Wednesday afternoon the flow increased considerably, possibly due to more ice giving way with the flow. The level in both the Mendenhall Lake and River was increasing by about 2 inches an hour Wednesday night and Thursday morning. Both met flood stages during the morning as the water continued to rise.

The water first cut off the road to the West Glacier Trail by Skater's cabin; reportedly about 1.5 feet deep early Thursday morning. Roads in the Mendenhall Campground were also covered as the water continued to rise, and the decision was made to close the campground. The campground was completely evacuated by 1pm.

One house on View Drive had water about 8 inches deep at it's first floor garage at 7am as the water began to cross the road there. Other residences in the area had water in the yards approaching the houses.

Due to the inaccessibility of the glacial lake, it was unknown how much water there was to drain. The Nation Weather Service had no forecast as of 8am for when the flooding would slow down. Like water draining out of a bathtub, the flow was expected to continue until the lake was empty at which time the flood would recede relatively quickly.

Measurements taken at lunchtime noted the Mendenhall River crested at 13.07 feet at 11:15am, and the Mendenhall Lake crested at 10.93 feet at noon. The River was down to 12.90 feet by 1:30pm, and the Lake was down to 10.47 feet at 2:15pm. Though the readings showed the peak of the flood was past, waters remain dangerous until the river returns to normal levels; a natural process that will take an unknown amount of time.

http://pajk.arh.noaa.gov/

By: Mikko Wilson - mikko@kath.tv

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