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June Monthly/2"d Quarter Report - 2002 <br />Page 3 <br />Mainstem Stream Monitoring and Reference Point Stream Monitoring <br />Sunnyside sampled the reference point (A-72) on June 5°i. The results for this sample are <br />attached. <br />The provisional flow at A-72 on June 5, 2002 was 340 cfs. This flow places the sample <br />result in the high flow category (Q>300cfs). The dissolved zinc value for this sample, <br />obtained by averaging the results from two labs, was 265 ug/I. <br />The index number for the June sample is calculated as follows: <br />Xi = 265 <br />Xf = 306 <br />Sf= 104 <br />. Ni = (265 - 306) /104 <br />Ni = -0.39 <br />The index number graph and updated reporting table are attached. <br />Evaluation of the normalized data: <br />The index value of -0.39 for June 2002 indicates that the dissolved zinc concentration at <br />the reference point A-72 was below the mean value of the reference data for the <br />intermediate flow class. Although the result was higher than June 2001's result, the flow <br />was approximately a third of the 2001 flow. Both results were below the reference data <br />mean. <br />The 12 period moving average of index values rose to +0.08 from +0.05 because the 265 <br />ug/1 is replacing a 221 ug/1 in the 12 month average. The 12 month average of (+0.08) is <br />below the +0.577 benchmark value in the Consent Decree. <br /> <br />