Figure 2. Physiography of
the Anchorage area and
Fort Richardson. (After
Yehle et al. 1986.)
marsh (Lawson et al. 1996a,b). Mean annual dis-
(Fig. 1). Generally sharp-crested ridges separate
charge of the Eagle River at a gauging station in
the U-shaped valleys, except to the northwest,
the City of Eagle River is about 15 m3/s; dis-
where they become relatively smooth crested or
charge peaked in September 1995 at 292 m3/s
gently sloping to nearly flat at their crests.
during the greater than 500-year flood (Kemper
et al. 1995, Brabets 1996).
Hydrography
Fort Richardson lies primarily in the Eagle
Ship Creek emerges from the Chugach Moun-
River and Ship Creek drainages; only the far
tains at the eastern edge of Fort Richardson and
southeast corner extends into the North Fork
flows just south of the cantonment area (Fig. 1).
Campbell Creek drainage (Fig. 1).
Its channel is incised along the flank of the
The Eagle River drainage area covers 600 km2
Chugach Mountains but becomes less so in the
and is 12% glacier-covered (Munter and Allely
center of Fort Richardson where it crosses an old
1992). The Eagle River flows in a well developed
alluvial fan. Updike et al. (1984) described Ship
meandering channel, through a large U-shaped
Creek as being the most economically important
valley for about 32 km from its source in the
stream in Alaska because it is used by three pow-
Chugach Mountains. The last 10 km of this reach
erplants, and the Anchorage and Fort Richardson
flows across glaciated lowlands on the north side
water treatment plants, as well as being the pri-
of the Elmendorf Moraine (Fig. 1). The modern
mary source of recharge to the Ship Creek aquifer
floodplain is incised into a paleo-outwash chan-
(up to 14 million gal. [53,000 L] per day [Ander-
son 1977]). The mean annual discharge of Ship
nel. The river straightens just east of Eagle River
Creek is 16.5 m3/s, with a peak discharge of 181
Flats. Here, channel migration has eroded uplands
m3/s, which occurred on 27 August 1989 (Brabets
composed of stratified glacial sediments. The
Eagle River discharges into the Knik Arm at the
1996).
mouth of the Eagle River Flats, a macrotidal salt
Clunie Creek drains a small lake east of the
3
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