Laserfiche WebLink
dominated by pasture grasses while weedy species were visually dominant on the <br />non-irrigated reach (see vegetation data in supplemental Report of 9/22/86). From <br />comparison of the adjacent flood irrigated and non-flood irrigated areas, it appears that <br />sub-irrigation has little impact on the agricultural productivity of the Foidel <br />Creek/Middle Creek Confluence AVF, and that flood irrigation is the critical function. <br /> <br />Significant increases in the salinity of alluvial ground water in the confluence area <br />would not be anticipated since the majority of the recharge to the aquifer occurs during <br />spring and early summer when Middle Creek and Foidel Creek flows are highest and <br />conductivity levels are lowest. Further dilution of alluvial waters would be provided <br />by Trout Creek irrigation drainage water. Since Trout Creek irrigation water supports <br />the critical function of the alluvial valley floor and the Trout Creek waters would not <br />be affected by the proposed operations, material damage to the quality of water <br />supplying the Foidel Creek/Middle Creek Confluence AVF would not occur. <br /> <br /> <br />3.The proposed operation will preserve, throughout the mining operation, the essential <br />hydrologic functions of the alluvial valley floor. <br /> <br />The essential hydrologic functions of the Foidel Creek/Middle Creek Confluence AVF <br />are flood irrigation primarily and, to a lesser extent, sub-irrigation, and both functions <br />would be preserved. <br /> <br />Flood irrigation on the Foidel Creek/Middle Creek Confluence AVF is by diversion of <br />unaffected Trout Creek water. Sub-irrigation does not play a major role in maintaining <br />the agricultural productivity of the AVF, but the quality of alluvial ground water <br />would be maintained above the material damage suspect level of 3 mmhos/cm due to <br />the fact that aquifer recharge occurs primarily in the spring and early summer when <br />stream salinity levels are lowest, and the alluvial water would be further diluted by the <br />low salinity Trout Creek irrigation drainage water. <br /> <br /> Alluvial Valley Floor Monitoring <br /> <br />Hydrologic monitoring as discussed in Section III, A and B of this document will be <br />sufficient to verify projections and monitor effects of mining on the quality and quantity <br />of water supplying the identified alluvial valley floors. Included in this monitoring plan is <br />a monitoring schedule for the Fish Creek AVF to assess for impacts. A surface water and <br />alluvial water site presently exists downstream of all Foidel Creek mining activities on <br />Trout Creek (site 1005 and well 008-AT-1). Surface water monitoring and alluvial <br />monitoring sites are located along both Foidel and Middle Creeks to assess possible <br />impacts due to the undermining of these perennial streams. <br /> <br />The Division finds that activities proposed by the applicant will not interrupt, discontinue, <br />or preclude farming on the alluvial valley floors that are irrigated or naturally subirrigated <br />(4.24.3(1)). <br /> <br />The proposed activities will not materially damage the quantity or quality of water in the <br />surface or ground water system described above (4.24.3(3) and 2.06.8(5)(a)(ii)). <br /> <br /> <br />46 <br /> <br /> Foidel Creek MineOctober 8, 2013 <br /> <br />