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water. The Wadge overburden and the Twentymile Sandstone are the two aquifers most likely to be affected by the Foidel Creek Mine. The following wells serve as the Foidel Creek Mine's ground water points of compliance: 97013TM (Twentymile sandstone), 008-77-58 (Wadge overburden), 008-AU3 (Fish Creek alluvium), and 008-AT-1 (Trout Creek alluvium). The mine's annual hydrology reports contain long-term data from these wells. These data show the Foidel Creek mine is in compliance with the Basic Standards for Ground Water at the ground water points of compliance. Surface water Several possible effects on the surface water system have been identified. Dischar¢e of mine inflow water to surface water drainages Mine water discharged to the surface water system will increase the conductivity, total dissolved solids (TDS), sulfate, and iron concentrations in the streams receiving the discharge. Total suspended solids, SAR, and pH could also increase due to these discharges. SAR may reach up to 6.2 in Fish Creek and 3.0 in Trout Creek. Sulfate and conductivity impacts are predicted for various segments of the stream system to be affected. TR-32 approved a plan which will allow the mine to dischazge considerable volumes of degraded water during high flow (great dilution capacity) and lesser or no discharge during periods of low flow (minimal dilution capacity). Lower Middle Creek -Impacts in this segment will be pronounced due to relatively small instream flows. There is no sulfate or irrigation standazd over this reach. However, due to standards on Trout Creek immediately below this segment, impacts will be minimized during most times of the year. Lower Fish Creek- The potential for significant impacts to lower Fish Creek, from mine water discharge site 115 (Fish Creek dewatering facility) downstream to the confluence with Trout Creek, exists. Although no sulfate standard applies over this reach, Fish Creek and adjacent alluvial valley floor areas are held to a 1500 umhos/cm material damage standard for irrigation waters. Modeling indicates that during low flow periods, the instream conductivity limit of 1500 umhos/cm could be exceeded. Therefore, the applicant has committed to maintain its mine water discharge rate from site 1 15 at a level which would prevent material damage (<1500 umhos/cm) by measuring upstream flow and quality and computing a discharge rate which would prevent downstream exceedance of the conductivity limit for irrigation waters. The sulfate standard for drinking water of 250 mg/I does not apply over this reach. Lower Trout Creek -The mine does not affect Trout Creek waters above the confluence with Middle Creek, but the flow rate and quality of Trout Creek is affected by site 109 (Portal area) discharge into Foidel Creek. Foidel Creek flows into Middle Creek upstream of the confluence of Middle Creek and Trout Creek. Modeling submitted during TR-32 review indicates the potential for significant impact over the lower Trout Creek reach due to mine water discharges. Conductivity over this reach should not be a problem, as the highest modeled value was 970 umhos/cm, which would not preclude irrigation usage. The sulfate limit of 250 mg/I over the period of June to February could be exceeded. Therefore, the mine will adjust discharge levels to prevent exceedance during this period in the same way conductivity levels will be regulated on Lower Fish Creek. The mine demonstrated that sulfate levels could be accurately determined by the existing relationship with conductivity (sulfate/conductivity = 0.32). When conductivity at the upstream site (site 301) equals or exceeds 740 umhos/cm, discharge from site 109 will cease entirely. Lower Trout Creek- Below Fish Creek- Flow rate and water quality will be affected by mine water discharge from site l 15 and site 109 (Portal discharge). Modeling performed by the applicant (TR-32) 12