Laserfiche WebLink
compliance. The dissolved and total recoverable selenium methods were <br />run as a quality control check. The acute standard, 18.4 ug /1, was not <br />exceeded. See the following NPDES effluent section for more details. <br />One sample from NPDES4 exceeded the total recoverable iron standard 1.0 <br />mg /l with a value of 1.55 mg /l in January. This result was likely do to <br />minor debris in the discharge pipe that may have been causing some <br />constriction of flow. After the sample was collected a small amount of <br />vegetation was removed from the pipe, the accumulated vegetation may <br />have contributed to the high total recoverable iron value. See the <br />following NPDES effluent section for more details. <br />In September 2003, the CDPHE resegmented Grassy Creek from Yampa Segment <br />12 to Segment 13e. Regulation 33 was further revised in December 2005 <br />and August 2008. Table 14 shows the new CDPHE receiving stream standards <br />for Grassy Creek. Table 15 provides a comparison of those standards to <br />water quality data collected this year from NPDES and stream sites in <br />the Grassy Creek basin. Standards that were exceeded are: <br />Parameter # of Sites / # of Excursions <br />Iron, Total Rec. 6/11 <br />Selenium 3/3 <br />All iron excursions were the result of high suspended solids. One sample <br />from NPDES4 exceeded the total recoverable iron standard 1.0 mg /l with a <br />value of 1.55 mg /l in January. This result was likely do to minor debris <br />in the discharge pipe that may have been causing some constriction of <br />flow. After the sample was collected a small amount of vegetation was <br />removed from the pipe, the accumulated vegetation may have contributed <br />to the high total recoverable iron value. See the following NPDES <br />effluent section for more details. <br />The chronic selenium standard, 4.6 ug /1, was exceeded at three sites <br />this year in the Grassy Creek basin. Site SSLGS drains the upper reaches <br />of Little Grassy Creek which are undisturbed by mining and exceeded the <br />standard once in June with a value of 6.9 ug /1. Site YSGS (Grassy Creek <br />downstream of mining) exceeded the standard once, with a value of 6.0 <br />18 <br />