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December 1996 Monthly/4th Quarter Report <br /> Page 5 <br /> Index numbers for November and December are as follows: <br /> November 7, 1996 December 13, 1996 <br /> Xi = 535 Xi = 705 <br /> Xf = 519 Xf = 519 <br /> Sf = 124 Sf = 124 <br /> Ni = (Xi-Xf)/Sf Ni = (Ni-Xf)/Sf <br /> Ni = (535-519)/124 Ni = (705-519)/124 <br /> Ni = 0. 13 Ni = 1.50 <br /> The index number graph and updated reporting table are attached. <br /> Evaluation of the normalized data: <br /> The index value of 0.13 for November indicates that this result is <br /> slightly more than the mean value for the reference data for the <br /> low flow class and the index value of 1.50 for December indicates <br /> that this result was significantly higher than the mean value for <br /> the reference data in the low flow class but not out of the range <br /> that might be expected over a time period similar to that covered <br /> by the reference data set. It appears that most of the increased <br /> zinc levels were originating from the Animas in December with <br /> Mineral Creek having somewhat elevated levels. The index values <br /> for both months were less than 2 therefore, no reanalysis, further <br /> evaluation or additional sampling is required. <br /> Please contact me if you have any questions on this report. <br /> Sincerely, <br /> n� ��'____, <br /> Larry Perino <br /> Reclamation Manager <br /> cc: EPA - Melanie Pallman <br /> Technical Enforcement Program 8ENS-T <br /> DMG - Wally Erickson <br />