1993-11-15_GENERAL DOCUMENTS - C1981017 (2)

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Mid-Continent Report; Nov. 15, 1993 Steve Renner/Harry Posey Page 2 that has been evaluated on a routine basis, and as such should offer the best indications of overall variations in water quality that may be traced to mining. I examined, but did not dwell on groundwater quality. Because the data show no obvious trends decipherable from the raw data, and because the AHRs indicated poor quality water with respect to TDS but no alarming changes, I elected to take a more rigorous statistical approach for the evaluation. By evaluating the following parameters at Station #20, I drew the conclusions which I will outline: ► date of sampling ► rate of flow P. conductivity ► total suspended solids P. total dissolved solids PROCEDURE 1. Plot Conductivity, TSS, and TDS relative to time. Conductivity and TDS in this system and in many others behave in very similar ways. Both are an indirect measure of the dissolved chemical components in the water that may affect aquatic life. TSS is a direct measure of the pftsical (sediment) component that may affect aquatic life, and is an indirect, partial measure of the dissolved component. 2. Evaluate the relationships between flow and Cond, TSS, and TDS by calculating the fit of the data about a regression line and calculating the standard deviation about that line. Curve-fitting is a way of identifying anomalous values that may not appear anomalous when compared with, say, the mean of the entire data set. For instance,for any given rate of,flow, there is a fairly narrow band of variation in TDS, and the TDS.Flow relationship is an inverse relationship, low flow correlates with high TDS and high flow correlates best with low TDS. A higher than average TDS value in the mid- to high-flow range may fall within one standard deviation of the mean of the entire TDS range, regardless of flow, but may still indicate some perturbation in the system.