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a <br /> 42 <br /> Figure 12 shows composition diagrams for samples taken from the Purga- <br /> toire and the alluvial wells near the Maxwell Mine. The numbers in paren- <br /> theses are the total dissolved solids concentrations. Complete data sets <br /> are contained in Appendix E, Table El . The composition of the water in the <br /> alluvium is very similar to that in the stream, the only significant dif- <br /> ference being a somewhat elevated sodium concentration in the alluvium re- <br /> lative to that in the stream. Apparently, the elevated sodium concentration <br /> in the alluvial waters is not caused by mining activities , because well <br /> AL 3-3 is located upstream of surface activities (with the exception of the <br /> access road) and of the point of mine discharge. The sodium is probably <br /> being contributed by dissolution of one or more sodium salts contained in <br /> the soils and alluvium. <br /> Allen Mine <br /> Similar computations were made to estimate the effect of the discharge <br /> ! from the Allen Mine on the stream quality. The results are shown in Table 8. <br /> Again, the indicated increases are believed to be conservatively large. <br /> • For these computations, a mean low flow in the stream of 3 cfs was used and <br /> the mine discharge was taken as 73 gpm. The mean values of the parameters <br /> measured at Stonewall as given in Table 5 were used for the upstream values. <br /> TABLE 8 Effect Of Allen Mine Dischar e On Stream <br /> Quality At Low Flow 3.0 cfs) <br /> Change In Concentration, mg/l <br /> PARAMETER QM = 73 gpm <br /> Total Diss. Solids + 32 <br /> 1, <br /> Alkalinity + 10 <br /> Boron + 0.004 <br /> f Chloride + 0.25 <br /> Iron (total ) - 0.02 <br /> Fluoride + 0.06 <br /> Sodi um + 14 <br /> Bicarbonate + 25 <br /> Zinc (total ) + 0.002 <br /> �J Also of concern is the effect on water quality in the Purgatoire of <br /> the active waste dump at the Allen Mine. An analysis similar to that used <br />