Draft Study Plan Vol 1 (PDF) - Alaska Power and Telephone Company

DRAFT DOCUMENT
Flushing Flows
GLH does not expect that flushing flows will be a requirement of the license. The
drainage area of the Project is only about 4% of the drainage area of the Chilkoot River.
Thus, any flushing releases from the Project would have little effect.
4.0 EXISTING ENVIRONMENT
HL&P, which was purchased by Alaska Power & Telephone Company (AP&T),
initiated field work on Connelly Lake, Chilkoot Lake, and along the access road, RS
2477, in the 1990’s. A fish survey was conducted in 1995 by ADF&G (report enclosed)
that found no fish in Connelly Lake or in its outlet stream (anadromous barrier found near
its confluence with the Chilkoot River).
The project boundary with project features is shown above in Figure 1. Figure 1
also shows topography of Chilkoot Lake and Connelly Lake and the surrounding area, all
of which are in the Haines State Forest.
Below is background information about the Chilkoot River Valley and Chilkoot
Lake.
Geography of the Study Area
The Skagway (B-2) Quadrangle, as shown in part in Figure 1, lies north of Haines
and west of Skagway at the upper end of Lynn Canal. The region is very steep and
rugged, with high dissected mountains, numerous high-gradient streams that discharge
into rivers occupying broad glaciated valleys with an array of glaciers and glacier-related
erosional and depositional features; at least eight major glacial cycles have occurred,
carving out valleys, grinding down rock and depositing moraines and layers of glacial till.
A warming of the climate caused a general retreat of late Pleistocene ice that ended
approximately 6-7 thousand years ago. At that time Alaska's glaciers were reduced to
their present size or smaller.
Post-glacial rebound, the uplift of terrain after the weight of glaciation is
removed, causes measurable elevation increases, especially along shorelines, mud flats,
and riverine basins. The presence of emergent marine deposits several hundred feet
above sea level demonstrates that the land has been uplifted relative to sea level since the
last major deglaciation of the region about 10,000 years ago. The rate of rebound has
been constant in this century and has been recorded at as high as 1.6 inches per year in
the region and 0.9 inches in the Haines townsite area. 2
Small glaciers are common on the higher peaks of the quadrangle, and glacial
processes have been important in its recent history. Peaks below 4,000 feet show
distinctively rounded summits and ridges that are indicative of burial by glacial ice, and
rocks along the shore of Taiya Inlet have been well carved, scalloped, and polished by ice
movement. The Takshanuk Mountain Range bordering the southwest side of the
2 Information courtesy of the Haines Borough Comprehensive Plan – 2004.
Draft Study Plan – June 2012 p. 12 Connelly Lake Hydroelectric Project