2004
GEESBROOKS CABIN FLOATED 5 MILES DOWN RIVER
TO LAND IN OUR FRONT YARD DURING THE LARGEST
FLOOD IN 50 YEARS.
TAKU RIVER FLOOD
Tulsequah Lake is at about 1,140
feet above sea level on the north side
of Devils Paw Mountain. The lake is
impounded by a distributary branch of
Tulsequah Glacier and is about 20
miles upstream from the mouth of the
Tulsequah River, a major tributary to
the Taku River. The U.S. Geological
Survey (USGS) has operated a
streamflow-gaging station on the
Taku River (station No. 15041200)
since 1987. Outburst floods from Tulsequah
Lake have occurred frequently and
have been documented by Marcus
(1960), Miller (1963), Post and Mayo
(1971), and the USGS (1988-99).
Tulsequah Lake is filled during
the summer months by rainfall and
by glacial melt. As Tulsequah Lake
fills, the lake surface rises until the
hydrostatic pressure at the base of the
ice dam causes the ice to float. As this
occurs, water begins flowing near the
base of the glacier. This flowing water
thermally erodes the dam, progressively
enlarging the opening. At
Tulsequah Lake, no surface drainage
is evident, and all discharge appears to
be through a subglacial tunnel. Data
from documented outburst floods
indicate that the flow of the Taku
River generally doubles or triples during
a 2- to 3-day period.
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