2016-02-25_PERMIT FILE - C1982056A (4)

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Presently, there are no active irrigation ditches established along the potentially affected portion of Fish Creek or Foidel Creek, which irrigate a designated alluvial floor within the limits of the planned WCR mining area. This is due to the fact that it is not economically feasible to establish an irrigation system on the limited acres formed by these meandering creeks. An alternate to active irrigation is the utility of sub -irrigation to enhance crop production. The potential for sub -irrigation to occur depends upon depth of rooting of selected species and water table elevation during the growing season. Data collected previously by P & M indicate there are restricted areas in which sub - irrigation does occur. The extent of this, based upon vegetation type, was verified during the 1997 growing season by vegetation production studies within the defined Fish Creek AVF. These areas are not cropped and are managed as unimproved rangeland. Mining -related subsidence has the potential to increase or decrease the productivity of these lands, dependent on their location and relationship to surface and ground water sources. There is, however, a greater potential for increased sub -irrigation and resulting increases in range productivity than for a decrease due to surface subsidence. In addition, these areas are so small relative to the overall area of agricultural use that any changes would have minimal effect on agricultural activities in the area. In considering the potential water quality impacts of mining and subsidence, ongoing monitoring at Station 900 on Foidel Creek, which is downstream of the previous mining in the Eastern Mining District and proposed mining in the WCR, does not show any changes that can be attributed to the previous mining and subsidence (refer to TC's recent Annual Hydrology Reports). In order to validate that no impacts will be realized to the AVF located downstream of its planned WCR operations, TC will continue to utilize its current downstream surface and alluvial water monitoring stations. Based on current mining plans, there is the potential that Station 900 may be impacted by mining -related subsidence in mid -2022. In order to address any potential downstream impacts from the planned mining operations, TC will relocate Station 900 (will become Station 900A) and the associated monitoring equipment downstream to the previous location of Station 304 at least one year prior to any mining -related impacts on Station 900. This will allow collection of a full year's monitoring data prior to any site impacts. These stations are presented on Map 13A, Hydrologic Monitoring Program. The stations will continue to be monitored under the existing monitoring schedule as described in the Wolf Creek Reserve — AVF Monitoring Program, Exhibit 4E-11. TC is the immediate downstream user of irrigation water, and does not foresee any impacts to its agricultural operations due to the potential loss of water from the system. In the unlikely event that significant losses occurred during the irrigation season, TC has sufficient water rights to augment any loss. TC's planned mining and any associated subsidence of portions of Fish Creek, Foidel Creek, and the associated AVF areas will not impact those AVF's located in the areas overlying or downstream of the operations. Any potential subsidence of the valley floor above the WCR mining area will result in the temporary formation of pooled areas similar to those which formed during undermining in the Eastern and Northern Mining Districts. These localized and temporary impacts will not significantly affect ongoing grazing operations, and may in fact, increase productivity and availability of water for livestock due to conversion of some adjacent upland vegetation to bottomland and minor increases in drainage surface areas. TC is not proposing any modification or reclamation activities for the flooded areas. PR15-11 2.06-25.9 11/03/15