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March Monthly/1°` Quarter Report - 2002 <br />Page 3 <br />Mainstem Stream Monitoring and Reference Point Stream Monitoring <br />Sunnyside sampled the reference point (A-72) on March 6`". The results for this sample <br />are attached. <br />The provisional flow at A-72 on March 6, 2002 was not available due to channel ice but <br />was less than 100 cfs, which places this sample result in the low flow category <br />(Q<IOOcfs). The dissolved zinc value for this sample, obtained by averaging the results <br />from two labs, was 545 ug/I. <br />The index number for the March sample is calculated as follows: <br />Xi = 545 <br />Xf= 519 <br />Sf= 124 <br />Ni = (545 - 519) /124 <br />Ni =+0.21 <br />The index number graph and updated reporting table are attached. <br />Evaluation of the normalized data: <br />The index value of +0.21 for March 2002 indicates that the dissolved zinc concentration <br />at the reference point A-72 was above the mean value of the reference data for the low <br />flow class. <br />The 12 period moving average of index values dropped to +0.20 from +0.26 because the <br />545 ug/1 is replacing a 634 ug/I in the 12 month average. The 12 month average of <br />(+0.20) is below the +0.577 benchmark value in the Consent Decree and remains at the <br />lowest Ieve1 since 12 month running averages have been calculated. <br />