1999-12-27_HYDROLOGY - M1977378 (2)

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November 1999 Monthly Report Page 4 Evaluation of the normalized data: The index value of +2.07 for November, 1999 indicates that the dissolved zinc concentration at the reference point A-72 was significantly higher than the mean value of the reference data for the intermediate flow class. In comparison to the November 10, 1998 sample result, the concentration is higher(697 ug/1 verses 528 ug/1) and the flow was also higher (201 cfs verses 129 cfs), although in the same flow class. The monitoring results for the Animas River at A-68 and Cement Creek at C-48 for November, received from the Bureau of Reclamation, indicate that both drainage basins had elevated dissolved zinc concentrations in November. Although the Consent Decree requires a reanalysis if the index number is above +2.0, Sunnyside did not request one from the labs because by splitting the sample for analysis, Sunnyside effectively confirms lab accuracy monthly and would routinely request reanalysis if the results from the two labs did not agree. This was not the case in November and Sunnyside is relatively confident the results are accurate. Although the index value is above +2.0, Sunnyside does not plan any additional monitoring unless December's results are also above+2.0. The 12 period moving average of index values rose to +0.76 from+0.66. This value is above the +0.577 benchmark value in the Consent Decree requiring a meeting to discuss monitoring results at the discretion of CDPHE. Although October and November's monitoring results are significantly above the reference data set and caused a rise in the 12 month running average, the underlying reason for the average being high is the May 6, 1999 sample result which contributes a N(i) value of+4.26 to the average which will influence the running average until it is no longer a factor. Please contact me if CDPHE would like to arrange a meeting to discuss monitoring results.