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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 data this year to <br />agricultural standards. This Paradox database generated table does not <br />include the units of concentration (mg/1 or ug/1) for each parameter. <br />The units used for each parameter are the same as those listed on the <br />standards table (Table 5) and are also the same as those used in the <br />water quality reports. The frequency column on Table 6 indicates the <br />number of exceedences out of the total number of samples (i.e., 1/2 <br />indicates one exceedence out of two samples). Below is a summary of <br />standards that were exceeded. Given in parenthesis is the source and <br />use of each standard. <br />Parameter # of Wells / # of Excursions <br />pH (CDPHE, irrigation) 2/2 <br />Fluoride (CDPHE, irrigation) 2/2 <br />Iron (CDPHE, irrigation) 2/4 <br />Manganese (CDPHE, irrigation) 10/23 <br />Selenium (CDPHE, irrigation) 3/3 <br />In addition, a total of seven samples from three sites had cadmium <br />values that were less than an elevated detection limit (30 ug/'1 vs. a <br />normal detection limit of 3 ug/1), which was higher than the CDPHE <br />standard of 10 ug/1. Likewise, the same samples had lead values that <br />were less than an elevated detection limit (200 ug/1 vs. a normal <br />detection limit of 20 ug/1), which was higher than the CDPHE standard of <br />100 ug/1. The cause of these elevated detection limits was a decision <br />by the laboratory to dilute the samples prior to analyses in order to <br />reduce the effects of interferences (primarily, high salinity). <br />Elevated levels of iron and fluoride may be attributed to natural (i.e., <br />not mining related) conditions, since elevated levels for those <br />parameters are not found in Seneca II spoil wells. In the case of <br />6