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C. Transfer of Wells No transfer of wells is proposed. Aii monitoring wells will be reclaimed prior to bond release (4.05.14). D. Probable H drolo is Conse uences A discussion of the probable hydrologic consequences of mining has been provided in Volume 4, Tab 7, Section VII.B of the permit application. Peabody Coal Company will revise the Probable Hydrologic Consequences section of the Seneca II Mine permit application by incorporating data and conclusions from the Seneca II Annual Hydrology Reports from the past five years. The revised section will be included in the revision required by Stipulation 27. Surface Water The Seneca II Mine is located in the upper Yampa River basin on the north flank of the Williams Fork mountains. The mine is located on a watershed divide between the Fish Creek drainage basin to the east and the Grassy Creek drainage basin to the west. Most of the previous mining at the site has occurred in the Little Grassy Creek basin which is tributary to Grassy Creek, a perennial tributary to the Yampa River. Mining in the Fish Creek basin began in 1982, in the Cow Camp Creek tributary basin. As mining in this drainage was completed, an area in another tributary basin of Fish Creek, Bond Creek, was disturbed. Mining activity will occur throughout the life-of-mine in this basin. The effects of mining on the water quality and quantity in each of these surface water basins is discussed below. Grassv Creek Drainage Basin Grassy Creek is a northerly flowing minor tributary of the Yampa River east of Hayden, Colorado. The Seneca II Mine is located about three miles upstream of the confluence with the Yampa River, and includes about 860 acres of disturbed lands within this drainage basin. Surface water monitoring sites are located above and below the mine to quantify mine-related impacts. Two ponds, NPDES 002 and 003, discharge between these two stations to Little Grassy Creek. The operator has conducted monitoring of discharge and water quality at the two surface sites in the Little Grassy Creek drainage since 1981. At the station above the mine (SW-S2-1) a mean discharge of 0.9 cubic feet per second (cfs> is characteristic of stream flow during the period June through September, the historic irrigation period in this portion of Routt County. A minimum flow of zero and maximum flow of 8 cfs has occurred during the period of record. TDS concentrations have increased over the past five years, from a 1987 average of 600, to a 1991 average of 835. _21_