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1 ~• • • <br />Steve Renner - 2 - May 6, 1987 <br />v <br />c <br />~~ 3. The report states that streamflow is perennial for stations SG4, FG1 and <br />SG5 and not intermittent as originally stated in the permit. As baseline <br />data was collected during a period of low streamflow, and subsequent data <br />have been collected in a high flow period, is this modification of the <br />description of streamflow regime based on the more recent data, or does <br />it include a consideration of the previous data as well? <br />4. An improvement in the hydrographs would be to scale the time axis by <br />water year or calendar year. It appears the statistical analysis <br />software (SAS) was used to develop these graphs. If appropriate and <br />available, control of the data plotting as mentioned above would improve <br />presentation and interpretation of the data. <br />„ram 1 5.) On page 91, the report states the mean TDS is 701 mg/L at FG1. This <br />~ru~ti ~~/ value is inconsistent with Table 27 which indicates the mean is 927 <br /><`Y mg/L. Which value is the correct mean TDS concentration at Station FG1? <br />6 Also on page 91, the statement is made that there does not appear to be <br />any distinct trends in TDS at Station FG1. There appears to be gradual <br />trend to a minimum in 1983 followed by a gradual rise in later years. <br />The report states there is a general inverse relationship between flow <br />and TDS at all stations. I would suggest a regression equation be <br />developed and reported to quantify this relationship, A similar <br />equation, developed after mining commences, would be an instructive <br />measure of changes in TDS, if any, due to mining. <br />7. In the discussion on exceedence of stream standards, the value of the <br />mean and maximum concentrations were presented for each constituent <br />exceeding standards during the period. As a suggestion, the percentage <br />of time exceedence was observed at each station, as was done for station <br />FG1, is an instructive measure and should be considered in future <br />reporting at all stations. <br />~~ In the discussion of springs on page 107, the report states that for the <br />Olson Spring (5-45), the concentration of sulfate does not meet CDH <br />Secondary Drinking Water Standards. Since no data has been reported on <br />Table 30 for sulfate it is difficult to verify the accuracy of this <br />statement. <br />/vj r <br />9551E <br />