Silver Creek - Division of Water Quality - Utah.gov

Silver Creek Watershed TMDL Final Report
6.0 SOURCES
6.1 Known Sources of Contaminants
Existing data were adequate for determining contaminant loading between data sampling points
along Silver Creek (contaminant loading is presented in pounds per mile of stream rather than by
responsible parties in Section 4.3). However, sufficient data are unavailable to adequately
allocate contribution of contaminants by specific site. Further, there are numerous smaller
source areas not specifically listed in Table 11 that undoubtedly contribute zinc and cadmium to
the creek. Table 11 identifies the major land owners within the various major source areas of
Silver Creek. Figure 22 identifies the major contaminated areas, which are referred to as source
areas.
Table 11 : List of Known Sources
Description
Owner
Upper Watershed Sources
United Park City Mines
Prospector Square groundwater drain Park City Municipal Corporation
Silver Maple Claims
BLM
Flood Plain Tailings
United Park City Mines
Richardson Flats
United Park City Mines
Meadow Area
Various Private Land Owners
All indications suggest that the metals of concern in this watershed are from historical mining
activities in the Park City area. Most of the mining activity occurred within the upper watershed,
primarily within Empire Canyon. Tailings from these mines were stored onsite or removed to
another location, typically downstream.
Several downstream locations were used to further reduce and process the discarded mine
tailings in an attempt to remove additional metals. The lower reaches of the stream have
significant amounts of mine tailings that are easily detected by the casual observer. These
locations include, but are not limited to, Silver Maple Claims, Richardson Flats, Flood Plain
Tailings and the Meadow area.
Contamination mechanisms vary from site to site but are generally attributed to surface or
ground water contact with mining related metals contamination. The upper watershed, due to its
overall steepness, is characterized by relatively high flow velocities and concentrations that have
a tendency to carry sediments and other materials to receiving waters, in this case Silver Creek
and its tributaries. Contaminated areas that are exposed or saturated by shallow ground water
will contribute to metals loading in the stream channels.
The Upper watershed source area includes discharges from two mining tunnels, the Judge and
Spiro Tunnels. The majority of these flows are captured for use in the Park City Municipal
drinking water system. Zinc concentrations for these tunnels have been reported at 0.81 mg/l for
the Judge and 0.22 mg/l for the Spiro Tunnel (NPDES Form 2A October 2002). Estimated zinc
loads from the respective tunnel flows that actually enter Silver Creek are less than 100 lbs. per
year from the Judge Tunnel and 300 lbs. per year from the Spiro Tunnel. These values are not
Page 35