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42 <br />~, <br />Figure 12 shows composition diagrams for samples taken from the Purga- <br />' toire and the alluvial we]ls near the Maxwell Mine. The numbers in paren- <br />t' theses are the total dissolved solids concentrations. Complete data sets <br />are contained in Appendix E, Table E1. 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 />f, lative to that in the stream. Apparently, the elevated sodium concentration <br />in the alluvial waters. is not caused by mining activities, becau::e well <br />AL 3-3 is located upstream of surface activities (with the excep+:ion •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 oq the stream quality. The results are shown in Table 8. <br />K Again, the indicated increases are believed to be conservatively large. -. <br />For these computations, a mean low flow in the stream of 3 cfs wz~s used and <br />the mine discharge was taken as 73 gpuo. The mean values of the parameters <br />I~ measured at Stonewall 'as given in Table 5 were used far the upstream values. <br />~ TABLE 8 Effect Of Allen Mine Oischarae On Stream <br />Quality At Low Flow Z3.0 cfs) <br />` Change In Concentration, mg/i <br />,I PARAMETER Qm 73 gpm <br />~ Total Diss. Solids + 32 <br />~4 Alkalinity + 10 <br />Boron + 0.004 <br />I 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 />Also of concern is the effect on water quality in the Purgatoire of • <br />~~ the active waste dump at the A11en Mine. An analysis similar to *.hat used <br />