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June 1998 Monthly and 2nd Quarter Report <br /> Page 3 <br /> The provisional flow at A-72 was 663 cfs which places this <br /> sample result in the high flow category (Q> 300 cfs) . The <br /> dissolved zinc value for this sample obtained by averaging the <br /> results from two labs was 232 ug/l . <br /> The index number for the June sample is calculated as follows: <br /> Xi= 232 <br /> Xc= 306 <br /> Sf= 104 <br /> Ni= (Xi - Xf)/Sf <br /> Ni= (232 - 306)/104 <br /> Ni= -0. 71 <br /> The index number graph and updated reporting table are attached. <br /> Evaluation of the normalized data: <br /> The index value of -0 . 71 for June, 1998 indicates that the <br /> dissolved zinc concentration at the reference point A-72 was <br /> significantly lower than the mean value of the data for the high <br /> flow class. In comparison to the June 10, 1997 sample result, the <br /> 232 ug/1 is an improvement of 33 percent. In comparison to the May <br /> 7 , 1998 sample, there was a significant improvement (232 ug/l <br /> verses 553 ug/1) between May 7th and June loth. <br /> Since the index value is less than +2 . 0, Sunnyside does not plan <br /> any additional monitoring or re-analysis. <br /> The 12 period moving average of index values for dissolved zinc at <br /> A-72 (graph attached) dropped to +0. 364 in June. This is a <br /> continuation of the downward trend observed since December, 1997 . <br /> If you have any questions on this report, please contact me. <br />