Dames & Moore, 1999 - USDA Forest Service

3 during the 1997 investigation indicate that water quality criteria for acute toxicity were exceeded during
April (zinc) and May (copper and zinc). The relatively lower habitat quality and the presence of
dissolved metals (primarily copper and zinc) at RC-3 may contribute to the reduced trout population as
compared to CC-I; however, trout populations at RC-3 were greater than the upstream reference reach
(RC-6/RC- 1) within Railroad Creek.
The Company Creek reference station is not comparable to the RC-3 station on Railroad Creek for a number
of reasons. The most significant being the proximity of the creek to the Stehekin River. which is a salmon
spawning ground. In contrast, RC-3 is located immediately upstream of Lake Chelan which is a deep water
body and not a fish spawning habitat. The stream substrate for Company Creek is also relatively high
gradient with numerous large cobbles and boulders which provide excellent trout habitat, and is dissimilar
from the RC-3 station. Consequently, the aquatic data collected at the Company Creek station are not
considered directly comparable to those of the RC-3 station.
Precipitation Affects on Benthic Macroinvertebrates
It appears that periods of precipitation have an affect on the benthic macroinvertebrates results. The aquatic
stations were sampled starting upstream at RC-6 and proceeded downstream to RC-3. After aquatic
sampling at RC-10 was conducted, and before sampling at RC-3 was initiated, a storm event occurred which
resulted in precipitation and increased stream flows in Railroad Creek. Afier the sampling was completed at
RC-3, a series of additional benthic macroinvertebrate samples was collected at RC-6 within 24 hours of the
precipitation event. The influence of precipitation affects on the benthic macroinvertebrates illustrates the
variability and lack of precision for the benthic macroinvertebrate population estimating method employed.
which is considered the scientific standard. Therefore, the data reflect the natural variability in the benthic
macroinvertebrate communities of the Stehekin River drainage.
8.2.6.2 Terrestrial Biota and Wildlife
The RI included an assessment of the terrestrial biota in the area of the Site. For wildlife purposes, the Site
and surrounding area was regarded as five sub-areas based on cover type. These sub-areas consisted of the
mine tailings, the north-facing slopes and old mine surface workings, the south-facing slopes, the riparian
area upstream of the tailings, the riparian area downstream of the tailings, and the tailings themselves.
The vegetation consisted of north-aspect coniferous forest in the area south of the mill and tailings piles,
south-aspect coniferous forest and open areas to the north of Holden Village, upstream riparian habitat west
of the baseball field and campground, downstream riparian east of tailings pile 3, and the tailings piles with
sparse planted and volunteer coniferous trees, deciduous trees and shrubs, and various grasses, forbs, and
sedges.
Terrestrial wildlife observed on the Site was generally consistent with the surrounding area. All of the
species were either observed andlor assumed to utilize the tailings piles at times.
Potentially federal- and state-listed and candidate species potentially occurring in the vicinity of the Site
include the Westslope cutthroat trout which is listed as a Species of Federal concern. This species of
cutthroat trout is found in Railroad Creek. However, the Westslope cutthroat has not been listed as
threatened and/or endangered. The peregrine falcon, bald eagle, northern spotted owl, gray wolf, grizzly
bear, lynx are listed as Special Status Species and have been observed in the Railroad Creek watershed.
\U~M-SEAI\VOLI\COMMOMWP\WDATA\W)5\REPORTSWOLDEN-2W\8-O doc 8-25 DAMES
17693-005-OI9Uuly 28. 1999:10:24 Ah4;DRAFT FMAL Rl REPORT
& MOORE