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Page 7 <br />TDS information on alluvial monitoring wells from annual hydrology reports48 is presented in <br />Attachments 1 and 2. There appears to be a trend of increasing values of TDS in TR-1.5. The <br />highest TDS value recorded in TR-1.5 is 4740 mg/l, observed in July of 2001. The levels of TDS <br />in WR-1 appear to have stabilized. The highest TDS value recorded in WR-1 is 4579 mg/l, <br />observed in 8/12/03. The peak from 1990 to 1994 monitoring of TR-3 and TR-4 was reported as <br />invalid due to equipment. The equipment was replaced in 1994. The highest reported value of <br />TDS in TR-3, during other periods of monitoring, is 860 mg/l, observed in May 2004. The <br />highest reported value of TDS in TR-4, during other periods of monitoring, is 960 mg/1, observed <br />in September 2004. TR-4 was damaged by stock in 2002, and a sudden increase in TDS values <br />may be a result of well repairs. <br />Groundwater Quality <br />Groundwater in the permit area generally deteriorates from the high ground on the east to the <br />lower grounds to the west a9 Water (circa 1981) from up-dip wells would be mazginally <br />satisfactory to unsatisfactory for irrigation, and would not be suitable for drinking. Total <br />dissolved solids is the limiting parameter.50 Water from springs at the toe of the slope, in areas <br />mined previous to 1981, would not be suitable for irrigation or drinking.S~ <br />TDS values in alluvial monitoring well TR-1.5 were as high as 1798 mg/I before 1994. <br />Trout Creek is a perennial stream. Flows at the upstream surface water monitoring station TR-a <br />are consistently lower than the flows at the downstream surface water monitoring station TR-bsz <br />Trout Creek flows downstream of the permit area are estimated, by visual assessments during <br />monthly inspections by the Division, to be greater that estimated upstream flows. Thus Trout <br />Creek is a "gaining" stream through this segment. Groundwater in the alluvial valley floor likely <br />flows towazds, and discharges into, the creek. <br />Colorado Discharge Permit System <br />Surface water discharges at the Edna Mine are regulated by the Colorado Discharge Permit <br />System permit number CO-0032638. There are 2 points of dischazge, Outfalls 004 and 007, from <br />three sedimentation ponds. Both of the outfalls discharge to Trout Creek. The three ponds <br />capture all surface flows and all known spring and seep flows from the mined portions of the <br />Permit area. <br />Well Locations and Use <br />°8 AHR 2004 <br />49 PAP page 2.5-SS <br />so PAP page 2.5-58 <br />s' PAP page Z.5-58 <br />sz 2004 ARR Figure 1 and PAP, Exhibit (Map) 4.6-26 <br />