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41 <br /> The equation on page 40 requires that the concentration of the <br /> I parameter of interest be known in both the mine discharge and the upstream <br /> 1 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 for the current discharge from the Allen Mine. This <br /> conclusion is based on the fact that the observed quality of the Maxwell <br /> 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 /> from the Allen because the current discharge from the Maxwell is very small . <br /> Furthermore, the composition and total dissolved solids observed at Well LA 221A <br /> near the Maxwell mine compare more closely with the Allen discharge than with <br /> the Maxwell , (Fig. 11 ) indicating that the eventual quality of the Maxwell <br /> discharge will be essentially the same as the current Allen flow. 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 most pronounced <br /> 9 <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 Maxwell 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 substantially 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 concen- <br /> trations are so small that it is not likely that they can be detected by <br /> even an intensive monitoring program. <br />