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. There appeared to be some seasonality to the overburden water chemistry at the New Horizon 2 mining area. In comparing spring versus fall chemistry, alkalinity, bicarbonate, chloride, potassium, sodium, sulfate and TDS levels tended to decrease in the fall. In comparing fall versus winter chemistry, alkalinity, bicarbonate, chloride, potassium and sodium levels increased and pH decreased in the winter. In comparing summer versus winter chemistry, alkalinity, bicarbonate, chloride and sodium levels increased and calcium levels decreased in the winter. In addition to chemical seasonality, there were some overburden chemical trends during the irrigation season with time. Well GW-N18 showed a decrease in calcium and an increase in sodium, bicarbonate, sulfate and TDS levels. Well GW-N 18 waterexceeded the CWQCC agricultural standards forfluoride and manganese and the water at Wells GW-N15 and GW-N21 exceeded the manganese standard. In comparison to livestock drinking water standards, Well GW-N15 waterexceeded the magnesium, sulfate and TDS standards and Well GW-N18 water exceeded the fluoride standard. Well GW-N21 water was suitable for use as livestock drinking water and water at well GW-N18P1 was suitable for both • agricultural and livestock use. Measurable trace element concentrations in the overburden aquifer included aluminum, arsenic, boron, cadmium, cobalt, fluoride, iron, lithium, manganese, nitrate, selenium, vanadium, silverand zinc. The highestconcentrations ofcadmium, nitrate, selenium and silver were measured in the overburden aquifer at the New Horizon 2 mining area. Three wells (GW-N14, GW-N17P1 and GW-N20) monitored the Dakota coal aquiferwaterquality in the NewHorizon2miningarea. The individualwaterqualityanalysesfortheDakotacoalaquifer wells in the New Horizon 2 mining area are presented in Peabody Appendix 7-4. The well locations are shown on Map 2.04.7-1. The three Dakota coal monitoring wells exhibited two watertypes during periods of irrigation. Wells GW-N14 and GW-N30 showed magnesium calcium sulfate water types and Well GW-N17P1 showed a sodium sulfate water type. During the non-irrigation periods, Well GW-N20 changes to a calcium magnesium sulfate water type. The only significant TDS change when comparing irrigation versus non-irrigation periods was at well GW-N20. The TDS level decreases 672 mg/I during periods of no irrigation. Slight TDS increases occured at Wells GW-N14 and GW-N17PI • (REVISED6/28/01) 2.04.7-14