Dames & Moore, 1999 - USDA Forest Service

Reference Reaches
RC-10. Railroad Creek immediately downstream from Seven Mile Creek. This location
was established to represent conditions from Ten Mile Creek downstream to Seven Mile
Creek and was selected to be compared with PNL's sampling Station - 6.
RC-3. Railroad Creek approximately 100 yards upstream from Lake Chelan. This location
was established to represent conditions of the lower segment of Railroad Creek prior to
Lake Chelan and was selected to be compared with PNL's sampling Station - 8.
Referring to Figure 4.6-2, three additional reference locations were identified within streams located outside
the Railroad Creek drainage for comparison to habitat conditions in Railroad Creek downstream of the
Holden Mine. Available aerial photographs were also reviewed and representatives of the USFS and
Washington Department of Game & Fish were contacted for assistance in identifying alternative reference
sampling locations outside the Railroad Creek drainage. The "non-Railroad Creek" reference reach
selection process initially included the identification of stream reaches that were within 'drainage basins
greater than 30 square miles within the Lake Chelan watershed, appeared to include a 100 meter reach
length suitable for comparison with reaches in Railroad Creek, and were located at elevations that
approximated the range of elevation of Railroad Creek downstream from the mine. This selection process
resulted in the identification of reaches that could possibly contain habitat similar to reaches in Railroad
Creek and reaches that may generally be compared to Railroad Creek. The process was carried out with the
understanding that the reference reaches selected would merely approximate conditions in Railroad Creek in
the absence of mine-related activities and no reach outside the drainage would be an exact match to any
particular reach in Railroad Creek.
Key habitat variables were identified to characterize stream reaches in the Lake Chelan watershed. These
habitat variables were associated with topographic map indices which were used to compare the reference
reaches with the map indices for the reaches in Railroad Creek downstream from the Holden Mine.
Table 4.6-1 lists the key habitat variables and their associated map indices.
The reaches of Railroad Creek were delineated by slope and identified from downstream to upstream as
Reach A (downstream), B, C, D and E (upstream) (see Figure 4.6- 1). The reference reaches were selected
to compare with these reaches based on a review of the watersheds in the Lake Chelan Basin, discussions
with the USFS, and the results of a reconnaissance conducted in September 1997. The only watersheds of
sufficient size that would potentially provide habitat comparable to Railroad Creek were in the upper
Stehekin River (upstream from Lake Chelan) and 25-Mile Creek. Within the Stehekin River watershed,
streams draining watersheds with large glacier areas were excluded because these would likely result in
significant differences in water quality due to glacial flour and associated impacts to sight feeding, sun
penetration and temperature of the water. In addition, watersheds that were not accessible by road or trail
were not considered.
The references for the reach of Railroad Creek from adjacent to the mine at Holden downstream to
approximately Seven Mile Creek (Reach D) have been previously established from the Glacier Peak
Wilderness boundary downstream to the Holden Mine influence (several hundred yards upstream of the
Vehicle Bridge). The two reference locations have been identified as RC-1 and RC-6 within this reach.
17693-005-0 19Uuly 19, 1999:4:5 1 PM;DRAFT FINAL RI REPORT