Dames & Moore, 1999 - USDA Forest Service

The banks are relatively nonvegetated, possibly as the result of human encroachment from the road (bridge)
that crosses the upstream end of the location and the general increase in human activities associated with the
USFS campgrounds nearby and the Lucerne boat dock. A mine adit is present approximately one-quarter
mile upstream of the sampling station.
Reference streams selected outside the Railroad Creek drainage were for the most part undisturbed, with the
exception of Company Creek which is immediately downstream from the' Chelan Public Utilities District
hydropower outfall and included a road crossing (Bridge). Bridge Creek and South Fork Agnes Creek were
located within wilderness areas and, as such, receive minimal human impact. Human access to both creeks
is attainable only by the Pacific Crest Trail.
Based on the habitat analysis results, BC-1 had the best overall habitat. The only parameter noticeably
suppressed at the Bridge Creek location was the "width to depth ratio." Unlike any of the other stations,
approximately 25 percent of the Bridge Creek location consists of a single pool of five to six feet maximum
depth which provide excellent trout cover and holding habitat for feeding. The remainder of the location is
relatively wide, but consists of numerous large cobbles and boulders which provide relatively good instream
cover for trout.
South Fork Agnes Creek (SFAC-1) provides instream trout cover in the form of scattered cobbles and
boulders and undercut banks and overhanging vegetation. Although the stream is relatively wide at this
location, several pockets backwater (downstream from the cobble and boulders) provide good holding
habitat for trout.
Of all the reference locations (Railroad Creek and non-Railroad Creek), the Company Creek location (CoC-
I) exhibits the most influence from human activity. As previously mentioned, CoC-I is located downstream
from the outfall of a hydropower plant. .CoC- 1 also contains a road crossing (bridge). The stream has high
gradient with numerous large cobble and boulders which provide excellent trout habitat. Vegetation is
nearly nonexistent immediately adjacent to the bank.
4.6.1.3 Benthic Macroinvertebrate Communities
The benthic macroinvertebrate communities within Railroad Creek and the reference streams exhibit a wide
range of conditions. .The benthic macroinvertebrate sampling and analysis procedure originally called'for
six to eight replicates to be analyzed at each location, pending the results of a power analysis on six
randomly selected replicates from each site. However, in an attempt to account for the anticipated
variation at each location all eight replicates were analyzed. The results of sampling eight replicates per
location were applied to six indices, the results of which provide indications of community health or
impairment. The indices evaluated are species richness (diversity), ratio of scrapers to filtering collectors,
ephemeroptera, plecoptera and trichoptera (EPT) and chironomid abundance, percent dominant taxon, EPT
index, and the ratio of shredders to total number of individuals collected. In addition to these indices, total
number of organisms per square meter were determined as an indication of productivity at each sampling
location. The results of these evaluations are presented in Tables 4.6-2a and b. The results are presented as
means for all eight replicates at a given-location. A listing of taxa and number. of individuals for each
replicate at each location is presented in Appendix 0.
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17693-005-019Uuly 19. 1999:4:51 PM;DRAFT FINAL R1 REPORT