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635 mg/1 on Curtis Creek upstream of the confluence of the FF Tributary ro <br />1002 mg/l TD5 downstream of the Rienau No. 2 Mine. The Northern No. 1 <br />sediment pond discharge passed through another stock pond, mixing with those <br />waters before discharging into Curtis Creek. The effect of sediment pond discharge <br />from Northern No. I are expected to make a negligible impact on natural TDS <br />levels in the FF Tributary and Curtis Creek AVF's. <br />The SAR levels of the FF Tributary AVF were likely wised during the period when <br />Northern No. 1 was pumping from the mine. A detrimental effect on soils may <br />have occurred in the 6.4-acre AVF due to these increased SAR levels, especially <br />during low flow months. No further degradation of quality in the FF Tributary <br />AVF should occur as the Northern No. I discharge on SAR levels in the Upper <br />Curtis Creek AVF were negated by mixing with the stock pond located upstream of <br />the FF Tributary confluence with Curtis Creek and by the increased flow of Curtis <br />Creek. <br />Curtis Creek Narrows <br />A stream reach designated as the Curtis Creek Narrows extends from one mile <br />upstream of the Rienau. No. 2 portal to one mile downstream. The valley of the <br />Narrows is described as containing streamlaid deposits. The extent of the alluvium <br />is limited due to the encroachment of large alluvial fans and Highway 13/789, which <br />have both displaced Curtis Creek. The Quaternary terrace deposits present vary <br />from eight to ten feet in width. The general dimensions of the channel are from <br />two to three feet wide and two feet deep. The alluvial fans present in the valley are <br />coalescing with very steep profiles. No imgation system is present in the Narrows <br />reach. The valley in this area is less than 25 feet wide. <br />Due to the narrowness of the valley floor, lack of flood irrigation and discontinuity <br />of the streamlaid deposits, the Division agrees with the applicant that the Curtis <br />Creek Narrows can be disregarded as an AVF. <br />Lower Curtis Creek AVF <br />The applicant has identified the Lower Curtis Creek valley as an AVF. This AVF <br />is located 1~/z miles downstream of the Rienau No. 2 portal where the valley widens <br />after passing off the front of the Rattlesnake Mesa. The valley broadens to a width <br />of 200 to 2000 feet. Portions of this AVF are flood-imgated meadow acreage. <br />The Rienau No. 2 Mine portal lies upstream 1'fz miles of this AVF. The surface <br />facilities have drainage controlled by a series of two sediment ponds. The Lower <br />Curtis Creek AVF has not been, and is not expected to be, impacted by the surface <br />facilities or subsequent reclamation. The sediment ponds will remain until such <br />time as the reclamation is adequate to control nrnoff and erosion from the surface <br />facilities. <br />14 <br />