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reduction did not significantly affect hay production, and drawdown has recovered18 since <br />mining ceased. The imgated croplands on the west bank of the Trout Creek AVF were <br />not affected, since the predicted lowering of the alluvial water table was confined to the <br />east side of Trout Creek. <br />Spoil Leachate Impacts on AVF <br />Material damage to the AVF would be suspected if the specific conductivity of Trout <br />Creek stream water or alluvial water significantly exceeded 2,300 mmhos/cm during the <br />July-August irrigation season. This material damage suspect level is based on Table 1 of <br />the Division's 1988 guideline, "A Description of the Material Damage Assessment <br />Process Pertaining to Alluvial Valley Floors", assuming an orchardgrass crop is grown <br />with calcium sulfate irrigation water. Trout Creek stream and alluvial water, <br />downgradient from the mine have not approached the suspect level. The data indicate this <br />trend can be expected to continue. <br />A major discharge point for Edna's Leachate is NPDES discharge outfall 007. Much of <br />this outfall's discharge comes from the Koll irrigation ditch whose flow is largely <br />composed of Leachate from Spoil Spring 1. That spoil spring's concentration of total <br />dissolved solids commonly exceeds 3000 mg/1, which equates to specific conductivity <br />greater than the material damage suspect level for Trout Creek stream and alluvial water; <br />therefore, the Division has imposed the following permit stipulation: <br />WATER FROM NPDES POINT 007 WILL NOT BE USED AS SURFACE IRRIGATION <br />WATER UNLESS THE OPERATOR FIRST DEMONSTRATESAND THE IJN/SION FINDS <br />THAT IRR/GAT/ON WITH THAT WATER W/LL NOT RESULT IN MATERIAL DAMAGE. <br />AVF Findines <br />Based on the preceding discussions of impacts from Leachate, physical disruption, and <br />dewatering, the Division finds: <br />1. The activities proposed by the applicant will not interrupt, discontinue, or <br />preclude farming on the alluvial valley floors that are irrigated or naturally <br />subimgated [Rule 4.24.3(1)]. <br />2. The proposed activities will not materially damage the quantity or quality of <br />water in the surface or ground water system described above [Rules 4.24.3(3) <br />and 2.06.8(5)(a)(ii)]. <br />3. The proposed activities will comply with the requirements of the Act and the <br />Regulations with respect to alluvial valley floors [Rule 2.06.8(5)(a)(iii)]. <br />4. Surface coal mining and reclamation operations will be conducted to preserve <br />the essential hydrologic functions of alluvial valley floors outside the permit <br />'$ 2006 Annual Reclamation Report <br />C-1980-001 Permit Renewal 5 Findings Page 32 of 33 Pages <br />