CU, AU, AND ZN-PB SKARN DEPOSITS (MODELS 18b,c; Cox and ...

Figure 4. Seasonal variations in A, stream flow and B, pH for surface water from monitoring sites adjacent to a tailings pile at an historic mill
site along Soda Butte Creek in the New World, Mont., district. These data reflect impacts caused by a tailings pile failure rather than drainage
from a mine. The tailings were removed from the McLaren copper-gold-silver mine and placed at the mill site several km south of the mine.
Two data sets, which represent sampling in 1974 (a) and 1975 (b), are plotted for sites 3 and 5. Dashed lines on B separate pH ranges in terms
of generalized effects of pH on aquatic ecosystems (based on Potter and others, 1982). Note that the average pH value for precipitation in this
area is 5.3. Water data from SCS Engineers (1984).
adits and open pits were made. Figure 7 is a preliminary contour map of pH ranges generated from the unpublished
data and augmented by data from the National Uranium Resources Evaluation (Broxton, 1979). Areas characterized
by high acidity (pH