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<br /> <br />at <br />The equation on page 40 requires that the concentration of the <br />1 parameter of interest be known in both the mine discharge and the upstream <br />waters. The upstream concentrations (Cu) used in the calculations are the <br />mean values for Stonewall (Table 5). Examination of the chemical data from <br />the discharges at the two mines and from well LA 221A led to the conclusion <br />that the long term quality of the Maxwell Mine discharge is best represented <br />by the mean values far the current discharge from the Allen Mine. This <br />conclusion is based on the fact that the observed quality of the Maxwell <br />l discharge varies widely due to the effect of activities within the mine. These <br />activities have a more pronounced effect on the Maxwell discharge than on that <br />1 from the Allen because the current discharge from the Maxwell is very small. <br />Furthermore, the composition and total dissolved solids observed at !Jell LA 221A <br />1 near the Maxwell mine compare mare closely with the Allen discharge than with <br />the Maxwell, (Fig. il) indicating that the eventual quality of the Maxwell <br />~ discharge will be essentially the same as the current Allen flaw. Therefore, <br />values of Cm used in the computations are the mean values for the Allen Mine <br />given in Table 5. <br />Discharge of mine water into the stream will have the mast pronounced <br />effect when the stream discharge is smallest. Available discharge records <br />at Stonewall above the two mines of interest and at Madrid below indicate <br />that the mean weekly low flows at these stations are about 5 cfs and 10 cfs, <br />respectively. The mean low flow at the Maxwell should be between these <br />two values. To be entirely on the safe side, a mean low flow discharge of <br />5 cfs was used for Qu in the above computations at the btaxwell Mine. A <br />conservatively large estimate of 20 cfs was used for computing the change <br />in concentrations at mean flow. It is believed that the increases indicated <br />in Table 7 are substantiaily greater than will actually occur. Even so, <br />the calculations show that the most significant effect will be to increase <br />the total dissolved solids. The indicated changes in trace element conc?n- <br />trations are so small that it is not likely that they can he detected by <br />even an intensive monitoring program. <br />