The aquifer of an alluvial plain between the Tanana and Chena Rivers near Fairbanks,
Alaska, generally consists of highly transmissive sands and gravels under water-table
conditions. During 1986-88, the U.S. Geological Survey studied the distribution of
ground-water levels in the alluvial plain between Moose Creek Dam and the confluence of
the Tanana and Chena Rivers. Moose Creek Dam is a flood-control structure on the Chena
River that impounds water only during high flows in the Chena River or during tests of the
dam's control gates. Ground-water-level information is needed to help design and place
septic systems, buildings, and drainage structures. Using 38 existing wells and 83 wells
drilled for this study during 1986 and 1987, ground-water levels were measured to
determine the depth to the water table, its seasonal variation, and its relation to
changes in river and reservoir stages. Water levels were continuously measured in 10 wells
and periodically measured in 110 other wells until August 1988. During 1989, water levels
were measured at least once in 59 wells. Three wells were equipped with water-level
recorders through 1993. River stages were measured continuously at one gaging station on
the Tanana River and at two stations on the Chena River.
During summer months of 1986-88, stages and discharges in the Chena River were
generally less than long-term mean monthly values, whereas mean monthly stages and
discharges in the Tanana River fluctuated above and below long-term mean monthly values.
Depths to water in monitoring wells ranged from slightly above land surface to about 21
feet below land surface. Depths to water in the alluvial plain were within 10 feet of land
surface in most areas, but were within 5 feet of land surface in many low-lying areas. In
general, the water table sloped to the northwest, from the Tanana River to the Chena
River, at a gradient of about 4 feet per mile. Water levels in wells within about half a
mile of either river responded rapidly to changes in river stage.
During summer months of 1989-93, stages and discharges in the Chena River were
generally higher than those during 1986-88, whereas stages and discharges in the Tanana
River were similar to those during 1986-88. During 1989, peak water levels were higher in
more than half the wells measured than during peak levels observed during 1986-88. Peak
water levels were also 1.9 to 3.3 feet higher in 1991 or 1992 than peak values during
1986-88 in three wells equipped with water-level recorders. Water levels in wells near
Moose Creek Dam responded rapidly to changes in water levels behind the dam. During one
impoundment, water levels in a well 0.1 mile from the dam rose approximately 7 feet, to
4.8 feet below land surface.
Glass, R.L., Lilly, M.R., and Meyer, D.F., 1996, Ground-water levels in an alluvial
plain between the Tanana and Chena Rivers near Fairbanks, Alaska, 1986-93: U.S. Geological
Survey Water-Resources Investigations Report 96-4060, 39 p. + 2 appendixes.
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