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Grassy Creek / Annand Draw <br />NPDESI0. <br />This sediment pond on Annand Draw was completed in August 1996. Flow was <br />observed at this site for the first time ever on February 24, 1997. Flow <br />at this pond is normally continuous. Average flow this year was 0.10 cfs <br />and its historic (1997-2017) average is 0.15 cfs. The timing of when flow <br />values are collected affects these averages. This pond was dredged out in <br />2002. Baseline data for this site, both downstream (Site YSA4) and <br />upstream (Site YSAF4) of the pond, have been provided in Appendix Dl of <br />the 2010 AHR. NPDESIO exhibits a slightly increasing TDS trend. However, <br />the peak value occurred in 2002. <br />NPDESII. <br />This pond exists on a Grassy Creek tributary and was completed in October <br />1997. Flow was first observed at this site in 1998. No discharge occurred <br />in 1999 or 2000. Average flow this year was 0.00 cfs and the historic <br />(1998-2017) average is 0.02 cfs. The timing of when flow values are <br />collected affects these averages. Due to high sediment level, this pond <br />was dredged out in the fall of 2003. TDS values exhibited an increasing <br />trend, with the peak value occurring in 2011. <br />Site YSGFS. <br />This site exists on Grassy Creek below the NPDESII pond. A statistical <br />summary of baseline chemistry data is provided in Appendix D1 of the 2010 <br />AHR. Its TDS plot indicates an increasing trend, with the peak value <br />occurring in 2013. This site is also a part of the Peabody Sage Creek <br />Mine monitoring program. <br />Site YSGS. <br />This site exists on Grassy Creek below all discharges from both the Yoast <br />and Peabody Sage Creek Mines. It became part of the required monitoring <br />program in October 1995. TDS values here are affected more by the Peabody <br />Sage Creek Mine than the Yoast Mine. TDS values recently display a stable <br />11 <br />