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Seneca II W AHR 2019 <br /> Requirement Requirement citation Comment <br /> 8. Basic Standards for CWQCC regulations Only sites WSD5, WSSF3, WSH7 and WSHFFI <br /> Surface Water 31.1.11 downstream of the Seneca IIW site have their waters <br /> used for irrigation. <br /> The manganese standard (0.2 mg/1), for agricultural <br /> use, was exceeded seven times at three different <br /> sites,including sprig surface water sites WSHFI, <br /> NPDES6,WSH7 during the 2019 water year. <br /> Based on CWQCC reg. 31,the standard of 0.2 mg/l, <br /> applies to plants grown in acidic soils (<6.0 pH). <br /> In alkaline soils,as found throughout the Yoast and <br /> Seneca II W region,the EPA standard would be 10 <br /> mg/l. The maximum manganese value observed at any <br /> surface site was 5.51 at site mg/1 at site WSH7. Pre <br /> mining manganese baseline values exceeded the 0.2 <br /> mg/1 standard as well. <br /> 9. Instream Numeric CWQCC regulation 33.0 15 monitoring sites exist within the Sage Creek, and <br /> Standards Hubberson Gulch/Dry Creek basins: WSD5, WSH7, <br /> WSH9, WSPG7, WSPG46, WSPG47,WSPG50, <br /> NPDES 5,NPDES 6,NPDES 16,NPDES 17 are within <br /> Hubberson Gulch/Dry Creek Basing and,, WSSF3, <br /> YSSF3, NPDES 9,NPDES 15 are located within Sage <br /> Creek basin. In addition, Spoil Springs 1-5 are found <br /> within the Dry Creek Basin. <br /> The receiving stream standard for Sage Creek is on <br /> Segment 13e of the Yampa River basin and, on Segment <br /> 13d of the Yampa River basin for Hubberson Gulch/ Dry <br /> Creek basin. <br /> The stream standards for Sage Creek and Dry Creek <br /> are based on aquatic life standards. Seneca II Ws' <br /> NPDES discharge limitations are based on constituents <br /> in Senecas'effluent likely to cause an exceedance of <br /> Segment 3e and 3d's numeric standards. Table 13 of <br /> the 2017 AHR provides a comparison of the standards <br /> to water quality collected from NPDES points and <br /> stream sites in the Hubberson Gulch/ Dry Creek Basin. <br /> Manganese and iron standards(total recoverable),were <br /> exceeded. Iron exceedances are likely the result of high <br /> suspended solids. Premining samples also exhibited <br /> elevated manganese and total recoverable iron values as <br /> stated in section 8 above. <br />