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detection limit for the batch of samples can be increased above the normal detection as a result of <br /> elevated concentrations in one or more samples within the batch or from unrelated instrument <br /> interference. The fluctuation in the lab's detection limit and the fact that cadmium has not <br /> historically been an issue at this well suggest that the increase in the detection limit for these <br /> three samples is likely unrelated to the presence of cadmium above the standard. A single <br /> dissolved selenium sample (43.7 µg/L) collected in May of 2016 also exceeded the 20 µg/L <br /> standard. This appears to be an anomaly as no other sample during the last five years exceeded <br /> 11.1 µg/L (Range: <1 — 11.1 µg/L). There were no exceedances of the GWPOC standards at <br /> YSAL3. <br /> B.) Instream Numeric Standards(CWQCC Regulation 33) <br /> The Colorado Water Quality Control Commission (CWQCC)has established segment specific <br /> aquatic life water quality standards for Grassy Creek(Segment 13i and 13j) and Sage Creek <br /> (Segment 13e) of the Yampa River. The water quality standards for these segments are included <br /> in CWQCC Regulation 33. Tables 1 and 2 include a summary of the water quality at the two <br /> Grassy Creek stream monitoring points over the last five years (2014—2018) and a comparison <br /> against either the Segment 13i or Segment 13j water quality standards. Tables 3 and 4 include a <br /> statistical summary of the water quality at the Sage Creek stream monitoring points over the last <br /> five years (2014—2018) and a comparison against the Segment Be water quality standards. The <br /> water quality in these streams is also compared to CWQCC Regulation 31 Agricultural Use <br /> standards. Additional discussion of the water quality in each stream segment follows. <br /> Grassy Creek— Yampa Segments 13i and 13j <br /> Total Recoverable Iron <br /> As described in CWQCC Regulation 33, a temporary modification of the chronic total <br /> recoverable iron standard is in place for Yampa Segment 13i which includes Grassy Creek from <br /> its headwaters to immediately above the confluence with Scotchmans Gulch. WQCC intends to <br /> continue to extend this modification until Phase 11 bond release has been obtained for all mines <br /> within the watershed and post-mine iron conditions can be adequately characterized. The iron <br /> temporary modification is applicable to stream point YSGF5 and Outfall 011. The 1 mg/L total <br /> recoverable iron chronic standard for Yampa Segment 13j is applicable to YSG5. <br /> SL-7 - 35 <br />