2016-05-04_REVISION - C1982056 (12)

Home Browse Search

comparison of the adjacent flood irrigated and non -flood irrigated areas, it appears that sub -irrigation has little impact on the agricultural productivity of the Foidel Creek/Middle Creek Confluence AVF, and that flood irrigation is the critical function. Significant increases in the salinity of alluvial ground water in the confluence area would not be anticipated since the majority of the recharge to the aquifer occurs during spring and early summer when Middle Creek and Foidel Creek flows are highest and conductivity levels are lowest. Further dilution of alluvial waters would be provided by Trout Creek irrigation drainage water. Since Trout Creek irrigation water supports the critical function of the alluvial valley floor and the Trout Creek waters would not be affected by the proposed operations, material damage to the quality of water supplying the Foidel Creek/Middle Creek Confluence AVF would not occur. 3. The proposed operation will preserve, throughout the mining operation, the essential hydrologic functions of the alluvial valley floor. The essential hydrologic functions of the Foidel Creek/Middle Creek Confluence AVF are flood irrigation primarily and, to a lesser extent, sub -irrigation, and both functions would be preserved. Flood irrigation on the Foidel Creek/Middle Creek Confluence AVF is by diversion of unaffected Trout Creek water. Sub -irrigation does not play a major role in maintaining the agricultural productivity of the AVF, but the quality of alluvial ground water would be maintained above the material damage suspect level of 3 mmhos/cm due to the fact that aquifer recharge occurs primarily in the spring and early summer when stream salinity levels are lowest, and the alluvial water would be further diluted by the low salinity Trout Creek irrigation drainage water. Alluvial Valley Floor Monitoring Hydrologic monitoring as discussed in Section III, A and B of this document will be sufficient to verify projections and monitor effects of mining on the quality and quantity of water supplying the identified alluvial valley floors. Included in this monitoring plan is a monitoring schedule for the Fish Creek and Foidel/Middle Creek Confluence AVF to assess for impacts. A surface water and alluvial water site presently exists downstream of all Foidel Creek mining activities on Trout Creek (site 1005 and well 008 -AT -1). Surface water monitoring and alluvial monitoring sites are located along both Foidel and Middle Creeks to assess possible impacts due to the undermining of these perennial streams. Currently Station 900 is the downstream surface water monitoring site for Foidel Creek. Projected mining in the Wolf Creek Reserve in mid -2022 may impact Station 900. Given this, the permittee has committed to moving the downstream surface water monitoring site for Foidel Creek from Station 900 to a new station (Station 900a), one year prior to any mining -related impacts on Station 900. The Division finds that activities proposed by the applicant will not interrupt, discontinue, or preclude farming on the alluvial valley floors that are irrigated or naturally subirrigated (4.24.3(1)). Page 51 of 52