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• impacts are anticipated. All of the above water sources are considered as alternative water supplies that can be used as part of WFC's augmentation plan for mitigating potential surface water rights impacts. It is estimated that WFC, following augmentation usage, will still have available approximately 54 acre-feet of excess consumptive use creditof(CCC)water. The alternative water sources will be selected based on the pre-impact quantity and quality of the source to be mitigated. Protection and Mitigation Plan Introduction. The only impact identified as having any significance at the New Horizon 2 mining area was the potential impact (diminished surface water flows) to surface water rights within the influence of the pit inflow drawdowns. A detailed augmentation and water rights plan is presented in Peabody Attachment 16-1 and any potential impacts will be fully mitigated. In addition to the mining practices designed to minimize disturbances to the hydrologic balance previously discussed, comprehensive ground and surface water monitoring plans have been developed to assess the possible impacts to the hydrologic system. The results of the monitoring programs have and will continue to be employed to support the conclusions that disturbances to the hydrologic balance will be minimal and that the potential uses of the ground and surface water systems affected by mining will not be changed. Additional ground and surface water monitors are proposed specifically to help insure that water rights are protected. Pending landowner and permit approvals, these sites will be incorporated into the monitoring program. The following monitoring plan discusses how the monitoring data or programs will be used to • determine impacts to the hydrologic balance. Ground Water Monitoring Plan Overburden, Dakota Coal and Alluvial Aquifer Quantity and Quality. Future drawdowns in the overburden, coal and alluvial aquifers will be compared against multiple year predisturbance (baseline) average water level fluctuations. Water level fluctuations as a result of irrigation, natural and water quality sampling stresses have been reasonably defined. Significant water level drops outside these multiple year ranges will be considered to be possible effects from pit pumpage. Water level drops in monitoring wells outside the projected zones of pit pumpage drawdown will be considered suspect unless a consistent deepening trend develops. Mining impacts on ground water quality will be compared against the multiple year baseline monitoring ranges established for each chemical parameter monitored at each site. Because a number of variables can affect water chemistry, only significant increases or consistent trends will be considered as possible impacts from mining. Spring Flows and Quality. Spring flows and quality changes at spring monitoring sites will be compared to ranges developed from multiple-year baseline monitoring data. Significant flow or quality deviations from the multiple-year ranges not explainable by climatic fluctuations will be considered to suggest impacts from mining. • (REVISED 2-00) 2.05.6(3)(b)(v) - 4