Dames & Moore, 1999 - USDA Forest Service

8.2.3 Surface Water
8.2.3.1 Railroad Creek
General
Railroad Creek originates approximately 10 miles west of the Site, from Lyman Glacier. The creek is also
fed by precipitation and snow melt. Due to the relatively steep gradient and the presence of relatively low
permeability glacial till and/or bedrock near the surface, the creek responds relatively quickly to
precipitation events.
A number of tributaries flow into Railroad Creek between the source area and the mouth of the creek at
Lake Chelan. Normal flow measurements in the Railroad Creek at the Site vary from a low of
approximately 50 to 70 cubic feet per second (cfs) in the late winter months to approximately 500 to 700 cfs
between May and July. Record high estimated flows were 3,000 cfs at the Holden, and 3.900 cfs at Lucerne
in May 1948.
Even though the total snowfall and snow depths were near record highs in 1997, the discharge flow
measurements for Railroad Creek were determined to be within the normal range; however, the period of
higher flow measurements lasted longer than for most previous recorded years.
The gradient of Railroad Creek is relatively steep at the headwaters, flattening to less than 1.5 percent at the
Site. The gradient remains relatively constant until approximately mile 5-112 (from the mouth) where the
gradient ranges from 4.3 to 6.9 percent. At the mouth, the gradient decreases to approximately 1.5 percent.
Due to the relatively steep stream gradient, Railroad Creek is generally found to have relatively low
volumes of fine-grained sediment within the stream substrate. Areas of observed sediment deposit
downstream of the Site include a beaver pond approximately one-half mile downstream of the Site, and a ,
log jam near the confluence of Sevenmile Creek.
Streamflow Monitoring Stations
The nomenclature for the surface water sampling locations in Railroad Creek was developed utilizing a
system initially established by the USFS. The sampling station upstream of the Site was initially established
by the USFS as RC-1 (Railroad Creek station 1). The sampling station immediately downstream of the Site
was designated RC-2, and the station at the mouth of Railroad Creek was noted as RC-3. However,
subsequent stations were added during the RI as the need arose for additional data, resulting in a total of
eleven Railroad Creek stations (RC-I through RC-11). This resulted in the nomenclature of the stations not
being in numerical order from upstream to downstream. The need to compare the RI data with historical
data precluded the ability to renumber the stations.
Streamflow monitoring stations used during the RI are shown on Figures 8.2-2 and 8.2-3. Stations RC-1
(established to be upstream of the mine-affected area), RC-2 (immediately downstream of the tailings piles),
and RC-3 (at Lucerne) were continued from previous work conducted by PNL and the USFS. New stations
include RC-4 (immediately upstream of the tailings piles), RC-5 (approximately one-half mile downstream
of tailings pile 3), RC-6 (established upstream of RC-1 to confirm the upstream limit of the mine-affected
area), RC-7 (adjacent to tailings pile 2), RC-8 (established upstream of RC-3 in an attempt to collect data
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17693-005-019Uuly 28. 1999,10:24 AM;DRAFT FINAL Rl REPORT