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r t <br />surface flow in Sudduth Draw by approximately 3% of the annual yield. The ion <br />balance of the surface water could be altered, and salt loading on the stream could be <br />increased by 2.7 kg per yr. These changes do not represent a significant change in <br />surface waters quantity or quality. As discussed in the summary of probable hydrologic <br />consequences, the effects are temporary and would be mitigated by reclamation. <br />3. Surface coal mining and reclamation operations would be conducted to preserve <br />throughout the mining and reclamation process, the essential hydrologic functions of <br />the alluvial valley floor. <br />Mining operations would not physically disturb the alluvial valley floor. Minor changes <br />in surface water supplied to the alluvial valley floor (as discussed above) would occur <br />during the mining phase of the operation. With successful reclamation and removal of <br />the sediment control system, the quantity and quality of surface flow supplied to the <br />AVF would return to natural conditions. <br />The applicant has suggested that the release of sediment deficient waters from the <br />sediment ponds would cause downstream erosion. Should this occur, the erosion would <br />begin immediately downstream from the sediment pond on Sudduth Draw. Given the <br />infrequent nature of runoff in this area, this erosion, as it occurs, should not be so <br />severe as to affect the essential hydrologic functions of Sudduth Draw. The potential <br />for erosion could be minimized if water from the mine pit is not discharged to Sudduth <br />Draw. <br />4. (Groundwater and Sub-irrigation in Sudduth Draw) The alluvium of Sudduth Draw is <br />recharged during snowmelt and precipitation events when this intermittent stream is <br />flowing. The stock ponds located along Sudduth Draw provide sufficient detention time <br />to increase recharge and to sustain sub-irrigation for longer periods of time. <br />There is a spring tributary to Sudduth Draw in the Old Sudduth Mine, Section 15, T9N, <br />R78W. Upon examining the color infrared aerial photos of the northern portion of Pit <br />3, it was determined that this spring does not provide significant water to Sudduth <br />Draw. Also Kerr Coal has determined that this spring increases salt loading in Sudduth <br />Draw (p. 780-126a). This spring will be destroyed during mining of Pit 3. This will not <br />significantly effect the flows in Sudduth Draw. <br />The mining of Pit 3 to its northernmost extent will impact the quantity of water flowing <br />in Sudduth Draw and sub-irrigation in its valley. Water will infiltrate the alluvium and <br />recharge the underburden, the Sudduth Coal seam and the overburden, and recharge <br />the spoil in the dewatered Pit 3. <br />The operation is in compliance with the requirements of this section. <br />Marr Strip Mine, C-80-006 29 December 9, 1992 <br />