2012-01-06_PERMIT FILE - C1982057A (4)

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Results of these analyses predict that Dry Creek will experience a 114 percent cumulative • increase in TDS to a point just upstream of fields irrigated by Temple Reservoir kt (see Exhibit 16-3, Tab 16). As the flow progresses downstream, chemical loading will decrease to levels at which background water quality of the receiving water would, in effect, become diluted by any additional surface water originating as spoil florv. Magnitudes of the TDS and chemical load increases similarly predicted in this analysis for Sage Creek are less pronounced. These impacts to surface water quality will occur over a long duration, but will result in minimal and insignificant impacts to downstream users. During mining, all three ponds (005, 006, and 009) will impound all water originating in the watersheds above. During the spring and early summer of years with normal or above-normal winter precipitation, much of the water impounded in each pond will originate as snowmelt or runoff from frontal storms. This water may serve to dilute the chemistry of water originating from replaced spoil material and disturbed areas. Runoff into these ponds will not contact any acid or toxic materials for any significant period of time. Impounded water will discharge into receiving streams only as a function of pond storage (evaporation, seepage, and industrial use withdrawals), and outlet capacities. After mining, both the 005 and 006 ponds will remain as parts of the postmini ng landscape, and • Pond 009 will be removed and reclaimed at bond release. During mining, the three ponds will impound runoff from each tributary and may possibly, especially during the irrigation season, result in depletions of flow in Dry and Sage Creeks. Because of the potential for depletions, which may preclude holders of water rights within both the Dry and Sage Creek basins from having sufficient water for their intended uses, a plan for augmenting water rights has been developed and approved by the Colorado State Engineer's Office (Division of Water Resources). The plan currently incorporates storage of water in Pond 006, and once Ponds 005 and 009 are constructed, Peabody will request modification of the plan to include these impoundments. Details of this plan may be found in Tab 16, Protection of the Hydrologic Balance. After mining, Ponds 005 and 006 will remain as permanent impoundments, and agreements with local landowners have been consuma ted that will allow them to use impounded waters in both 005 and 006 for purposes such as stock watering (see Appendix 16-1, Tab 16). The impacts of sediment ponds on downstream users will be long-term, but of minimal significance because of the following: 1) increases in chemical loading and TDS will not • preclude the water from being used for either existing or potential uses; 2) the increases 60