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Table 6 provides a comparison of ground water quality collected this <br />year to agricultural standards. This Paradox database -generated table <br />does not include the units of concentration (mg/l or ug/1) for each <br />parameter. The units used for each parameter are the same as those <br />listed on the standards table (Table 5) and are the same as those used <br />in the water quality reports. The frequency column on Table 6 indicates, <br />in this order: uncensored, that is, the number of exceedances above the <br />Method Detection Limit (MDL) / the number of exceedances between the MDL <br />and the Practical Quantitation Level (PQL) / censored, that is, the <br />number of sample values below the MDL but the MDL was higher than the <br />standard / the total number of samples. Below is a summary of standards <br />that were exceeded in the 2017 water year. Given in parenthesis is the <br />source and use of each standard. <br />n - ---- - - <br />Boron <br /># of Wells / # of Excursions <br />1/1 <br />pH (CDPHE, irrigation) 3/3 <br />Iron (CDPHE, irrigation) 3/3 <br />Manganese (CDPHE, irrigation) 4/4 <br />The Wadge Coal Well WW14 exceeded the boron standard, 750 ug/l, with a <br />value of 900 ug/l in May. According to the CDPHE, the 750 ug/l standard <br />is set for sensitive crops (CDOH, Reg. 41, 2008), and that the limit <br />otherwise is 5000 ug/l. None of these sensitive plant species are grown <br />commercially in this area. <br />Elevated levels of iron (i.e., greater than 5 mg/1) may be attributed to <br />natural (i.e., not mining related) conditions. The one bedrock well <br />(WW14) that often exhibits high levels (17.6 mg/l this year) may have <br />higher than usual concentrations of iron pyrite in the rock. The high <br />levels of iron displayed in the alluvial wells this year may be the <br />result of organic matter and plant debris present in the alluvium (Hem, <br />1985, pg. 77). <br />8 <br />