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_pl_ C. Impacts on Ground Water The Dorchester No. 1 mine workings have the potential to deplete the quantity of ground water through mine-induced ground water inflows. The mining operation will induce inflows by dewatering the coal seam and the associated roof and floor strata as the mine workings advance. In addition, overlying aquifers could be dewatered through subsidence-related fractures. Locally perched ground water aquifers in strata above the workings may be dewatered through subsidence cracks or fractures. Thus the water will drain down through the fractures to the voids created by the mine. The greatest potential effect on ground water is for perched aquifers in the Vermejo and the overlying Raton Formations to be dewatered by subsidence. Wells which use these perched aquifers could experience some drawdown effects. However, due to the transmissivity of the aquifer, the fact that aquifers in this area tend to be laterally discontinuous, and the effects of past surface and underground mining, ground water impacts (both magnitude and extent) are difficult to predict. The operator is obligated to comply with Rule 4.05.15 pertaining to water rights and replacement if an owner is injured as the result of the operation. The ground water monitoring plan has been designed to identify ground water impacts before they extend to water supply wells. these measures will ensure a better understanding of the impacts to the ground water system and protection of water resources in the future. The existence of the mine workings will permanently modify the pattern of ground water flow. The flooded mine constitutes a region of essentially infinite permeability that will tend to cause ground water to preferentially pass through the workings. The water passing through the flooded mine may be degraded in quality, relative to that in the undisturbed strata. Another potential ground water impact due to subsidence would be fracture-related drainage of surface water bodies. These surface water bodies would be the mine water ponds, ephemeral drainages, and the perennial Newlin Creek. Dewatering the ponds would short-circuit the water system during mining, which is not considered a significant impact. Also, the effects to ephemeral drainages would be minimal. However, diverting streamflow of Newlin Creek underground might be significant. The interception of surface water or shallow ground water by underground workings presents a potential impact to water availability to the Newlin Creek. However, as previously mentioned, Newlin Creek is diverted upstream of the mine by the city of Florence. This reduces the significance of any depletions to the creek by the mine. The mine is presently incurring water sources in both the north sections and the southern sections of the mine. No quantitative studies have been undertaken to date. Quantification of total depletions to Newlin Creek are nearly impossible to make, since mining adjacent to this creek was primarily done from late 1900 through the 1970's. Most of these areas have been sealed off and, therefore, could not indicate reliable inflows. However, the mine inflow study to be conducted by the operator will provide valuable data in the future in impacts from the Dorchester operation.