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Comparison of Ground Water Quality to Water Use Standards. SCC has <br />compiled a list of ground water standards for agricultural uses (Table <br />5). This list is composed of Colorado Department of Public Health and <br />Environment ground water standards (CDPHE, Reg. 41, May 2008). <br />Table 6 provides a comparison of ground water quality to agricultural <br />standards. This Paradox database generated table does not include the <br />units of concentration (mg /l or ug /1) for each parameter. The units used <br />for each parameter are the same as those listed on the standards table <br />(Table 5) and are also the same as those used in the water quality <br />reports. The- frequency column on Table 6 indicates, in this order: <br />uncensored, that is, the number of exceedances above the Method <br />Detection Limit (MDL) / the number of exceedances between the MDL and <br />the Practical Quantitation Level (PQL) / censored, that is, the number <br />of sample values below the MDL but the MDL was higher than the standard <br />/ the total number of samples. Below is a summary of standards that were <br />exceeded. Given in parenthesis is the source and use of each standard. <br />Parameter <br />pH (CDPHE, irrigation) <br />Iron (CDPHE, irrigation) <br />Manganese (CDPHE, irrigation) <br /># of Wells / # of Excursions <br />3/3 <br />3/3 <br />4/4 <br />Elevated levels of iron (i.e., greater than 5 mg /1) may be attributed to <br />natural (i.e., not mining related) conditions, since the highest level <br />of iron found in spoil springs at this mine this year was 0.34 mg /l. The <br />one bedrock well (WW14) that often exhibit high levels may have higher <br />than usual concentrations of iron pyrite in the rock. The high levels of <br />iron displayed in the two alluvial wells this year may be the result of <br />organic matter and plant debris present in the alluvium (Hem, 1989, pg. <br />77). <br />High manganese values may, in part, be due to recharge from the spoil <br />aquifer, although high values are often common, especially in alluvial <br />material (Hem, 1989, pgs. 86 -89). This standard is used to protect crops <br />10 <br />