ANCHORAGE (AP) -- Advancing Hubbard Glacier appeared to hold firm early this week, scientists and forest service officials said Tuesday.
The glacier is 150 feet from closing off the entrance to Russell Fiord
Overflights on Sunday, Monday and Tuesday showed the glacier to be moving little if at all, said Tricia O'Connor, a U.S. Forest Service ranger in the Tongass National Forest. Hubbard is pushing a gravelly moraine before it, and that likely would seal the channel before the ice closes with Gilbert Point.
''There are a lot of variables, not the least of which is the monstrous tidal flux in and out of Russell Fiord,'' said Dennis Trabant, a glaciologist with the U.S. Geological Survey. ''That's what's keeping it open. It's able to erode the moraine about as fast as it's being pushed forward.''
The glacier could slam tight against Gilbert Point, choking off the mouth of the fiord and trapping harbor seals, porpoises and possibly other marine mammals in what would soon become a freshwater lake system. Or Hubbard could begin its slow seasonal retreat and leave the fiord open for another year.
Hubbard is on a ponderous, centuries-long march south that eventually may carry it over Yakutat, a fishing town about 35 miles south. Sooner or later, it is sure to close off the fiord, as it did temporarily in 1986. But it's impossible to predict if that will happen this summer, next year or in 20 years.
If the glacier forms an ice dam that closes the channel into Russell Fiord permanently, the resulting lake would swell with runoff from snowmelt and precipitation until it either breaks through the dam, as it did in 1986, or overflows through a spillway into the Situk River basin, a world-class steelhead fishery near Yakutat.
To do that, the newly formed lake would have to rise to about 125 feet above sea level. Trabant said that could take 12 months to 16 months.
With the glacier again threatening to close the fiord, the Forest Service has revived studies to anticipate the consequences of flooding the Situk.
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