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37 shown graphically in Figure 11. This figure shows the similarity of compo- sition of the mine discharges. The major difference in relative composition ~~ of the stream waters as compared to the mine discharges is a lower concen- ' tration of sodium. Otherwise the compositions are quite similar. The J combined concentration of dissolved salts in the mine discharges are greater than in the stream, however. Table 6 is a compar•isan of the chemical analyses (Appendix E, Table E2) of waters taken from the three bedrock wells established as part of this study with the means from the Maxwell Mine discharge. The data for well LA 221A is believed to be representative of the quality of the undisturbed waters in the coal seam. The differences observed between the water quality in LA 22111 and of the mine discharge is attributable to activities within r the mine and, to same extent, to sample and analytic variability. The large p¶ concentrations of total iron and manganese are attributed to the steel casing and the elevated total iinc is due to the galvanized iron discharge pipe used in the pumping system. The concentrations of dissolved iron, manganese and zinc are meaningful, but the total concentrations of these elements are • nat. i+ Mater pumped from LA .264 is believed to be produced from a thin fractur- l. ed zone at a depth of about 12 ft. as discussed previously. Even though the water sample from this well represents a zone high in the overburden, the composition and total Concentrations are very similar to the corresponding parameters from LA 221A. This observation suggests a uniform water quality I. throughout the profile. ~ The sample from well LA 218A is not representative of the coal seam ~~" waters. Because the productivity of the well was small, a volume of water sufficient to displace the water standing in the well bore was not pumped, and the sample is believed to be contaminated ~.vith cement which would ac- count for the high pH and large concentration of carbonate. The chance in the quality of waters in the Purgatoire River as a result of mine discharge is an item of particular concern. The estimated change in seiected parameters due to the Maxwell Mine discharge are present- . ~ ~ ed in Table 7. The mass balance-mixing model: