2008-05-06_REPORT - C1980005 - Laserfiche WebLink

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Parameter # of Sites / # of Excursions Manganese (CDPHE irrigation) 10/13 This summary indicates that only three CDPHE surface water agricultural use standards were exceeded. The manganese standard was exceeded at ten sites. However, as indicated in the recently revised CDPHE Regulation 31, the standard of 0.2 mg/1, applies to plants grown in acidic (<6.0 pH) soils. In alkaline soils, as are found in the Seneca II region, a more appropriate (EPA) standard would be 10 mg/1. The maximum manganese value observed this year at any NPDES outfall was 1.19 mg/1 at NPDES 003. All stream sites had manganese values less than 0.70 mg/1, and all spoil springs were less than 5 mg/1. It should also be noted that the site on Grassy Creek (SSG1) that is upstream of Seneca II discharges also experienced exceedences of the 0.2 mg/1 standard. Table 11 shows the CDPHE receiving stream standards for Fish Creek (Yampa Segment 13b) Table 12 provides a comparison of those standards to water quality data collected this year from NPDES and stream sites in the Fish Creek basin. Standards that were exceeded are: Parameter Iron, Total Rec. Mercury Selenium Sulfide # of Sites / # of Excursions 2/2 2/2 2/4 4/4 All iron excursions were the result of high suspended solids. None of the iron excursions were at a NPDES site. Two samples exceeded the mercury standard (0.01 ug/1) this year. NPDES4 and 8 excee ded the standard on February 5 with values of 0.0230 and 0.0227 ug/l, respectively. These were the first samples analyzed using . the new low d i b level mercury test F b d d (MDL = 0.0002 ug/1) f it d hi h The excursions th h serve n o ruary are an or e er o magn u e g er an any ot er 19