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Comulative Hydrologic Impacts The Cumulative Hydrologic Impact Study (CHIS) assess the projected cumulative hydrologic impacts of all existing and anticipated mining operations in the general area of the proposed Coal Gulch underground mine. The cumulative impacts include both surface and ground water impacts, however, the general area as defined for surface and ground water do not coincide. Ground Water Cumulative hydrologic impacts to the round water regime will not occur. The Coal Gulch Mine will be mining the "A seam in the Menefee Formation. This is the only anticipated mine in this seam within the San Juan structural basin (see Section IV, Geology). Given the relatively impermeable zone below the "A" seam, the large distance separating other mines in the area and the influence of minor structural features within the regional basin, there will be no cumulative effects to the ground water system from mining at Coal Gulch. Surface Water The surface water CHIS encompasses Coal Gulch from the mine site to its confluence with Lightner Creek, and Lightner Creek to its confluence with the Animas River near Durango. Coal Gulch, an ephemeral stream at the proposed mine site, is confluent with Sheep Sprin s Gulch and Cherry Gulch immediately below the mine on the south side of Hig~way 160. The main stem of Coal Gulch below this point flows for about a mile before its confluence with Lightner Creek. From this point, Lightner Creek flows for about four (4) miles to its confluence with the Animas River near Durango. Pueblo Coal Company's Carbon Junction Mine (CMLRD Permit No. C-054-82) is located downstream of the Lightner Creek confluence within the Animas River drainage basin. The Carbon Junction Mine has been designed to minimize the impacts to the quality of the Animas River. This is accomplished by using sediment ponds which hold drainage from the disturbed areas. These ponds generally discharge only in the spring during periods of snowmelt. When these small flows eventually reach the Animas River, they are immediately diluted. The impacts of the Carbon Junction Mine to the Animas River drainage system are insignificant. Based upon the distance between sites and the amount of dilution which would occur between sites, the Division finds that no cumulative impacts will occur to either the surface or ground water systems.