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located within the Grassy Creek drainage. A 45 acre area neaz the confluence of Little Grassy Creek and Grassy Creek and a 40 acre area along Little Grassy Creek which have been identified as AVFs remain exempt and, as such, were not reevaluated. Non-exempted azeas in the Fish Creek drainage basin were reexamined in 1986, in conjunction with a regional AVF study conducted by the Division, to identify if any significant impacts would occur from the proposed operations at Seneca R Mine. The areas which were reexamined as potential AVFs within the Fish Creek basin include alluvial bodies along two tributaries of Fish Creek, referred to as Cow Camp Creek and Bond Creek, and the reach of Fish Creek between Cow Camp Creek and the confluence with Trout Creek. Based on the Division's review of materials submitted by the applicant on May 27, 1981 and infrazed aerial photography reviewed more recently, the alluvial bodies adjacent to Cow Camp and Bond Creeks did not meet the requirements for AVFs. This negative deternilnation was made in both instances due to the fact that the meandering nature of the channels severely limits the farmable acreage within each drainage. During the Division's review of the adjacent Foidel Creek life-of--mine permit revision (C-82-056), the Division reevaluated potential AVFs in Twentymile Pazk. Infrared photography and field investigations indicated that the Fish Creek alluvial body was, in places, flood irrigated, and was generally sub-irrigated, potentially farmable land. Based on these investigations, the Division has determined that the Fish Creek alluvial body met the criteria of an AVF. This AVF extends the length of Fish Creek to its confluence with Trout Creek and along the length of Trout Creek to its confluence with the Yampa River. Effect of Minine on Identified Alluvial Vallev Floors Water quality data were supplied in the renewal application from monitoring of surface water stations on Cow Camp and Bond Creeks, tributaries to Fish Creek. Mining in the Fish Creek drainage basin began in 1982. Since that time increases in both flow and total dissolved solids (TDS) concentrations have been observed. Whereas flow in the channel immediately below the mine, Cow Camp Creek, was ephemeral prior to mining, perennial flow is now observed at the permit boundary. This effect is attributable to spoil aquifer dischazge, as well as an increase in runoff from mined lands, and a decrease in evapotranspiration due to removal of vegetation from mining azeas. Recent observations have indicated, however, that stream flow is not maintained in the channels of the two tributazies during the months of August and September neaz their confluences with Fish Creek. The surface effects of water dischazged from the mine on the downstream AVF locations is restricted to the months of June and July. Subsurface effects aze expected to predominate in August and September. 39