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<br />1397 <br /> <br />In addition to the inorganic constituents, all of the groundwater samples collected <br />were analyzed for selected pesticides, A listing of pesticides was compiled for analysis <br />based on those substances that have recently been, or are currently being utilized in the <br />Arkansas River Valley according to agricultural officials there, Budget restrictions would <br />not allow testing for all pesticides used in the study area, To reduce the analysis cost, each <br />pesticide was weighted according to its chemical properties of persistence and mobility in <br />the environment, amount of active ingredient used per acre, and the amount of acreage <br />within the study area that the pesticide was used on, Pesticides were then selected according <br />to their final score and the ability of the laboratory to detect their presence, <br /> <br />GROUND WATER MONITORING RESULTS <br /> <br />The results from this sampling program have been entered into the CDPHE <br />Groundwater Quality Data System, a database specifically designed and maintained by the <br />WQCD to store ground water quality data, Reports may be generated from the database on <br />ground water quality in any area of the state from all data sources available, A complete <br />printout of all water quality data from this survey is provided in Appendix A. <br /> <br />Analysis of the laboratory results indicates that ground water in portions of the study <br />area has been impacted by nitrates and certain pesticides, The major inorganic contaminant <br />of concern is nitrate, Nineteen (19) of the one hundred thirty nine (139) wells sampled (14%) <br />showed nitrate levels in excess of the EPA standard for drinking water (10 mgIL) (Figure 2), <br />One hundred twelve (112) wells (80%) tested positive for nitrate but were below the EPA <br />standard, Eight (8) wells (6%) tested below the detection level of 0.5 mgIL, <br /> <br />Nitrate below <br />detection ievel <br />of 0,5 mg/L <br /> <br />80% ' <br /> <br /> <br />18 10 -19,9 <br />mg/L <br /> <br />1 39,1 mg/L <br /> <br />Nitrate present at <br />0,5 - 9,9 mgfL <br /> <br />Nitrate exceeds <br />Drinking Water Standard <br />of 10 mg/L <br /> <br />Colorado Oept. Health 1994 <br /> <br />, <br /> <br />FIGURE 2 - Nitrate levels in Arkansas Valley wells Chart showing distribution of <br />nitrate levels in the Arkansas River Valley all~vial aquifer, 1994, <br /> <br />5 <br /> <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />I <br />. <br />