| (3) Criteria for determining whether a surface coal mining operation will materially damage the quantity or quality of waters
subject to subparagraphs (A) and (B) of this paragraph include, but are not limited to: (A) potential increases in the concentration of total dissolved solids of waters supplied to an alluvial valley floor, as measured by specific conductance in millimhos, to levels above the threshold value at which crop yields decrease, as specified in Maas and Hoffman, Crop Salt Tolerance--Current Assessment, Table 1, A Salt Tolerance of Agricultural Crops, unless the applicant demonstrates compliance with subparagraph (B) of this paragraph. (i) Salt tolerances for agricultural crops have been published by E.V. Maas and G.J. Hoffman, in a paper titled Crop Salt Tolerance--Current Assessment, contained in The Journal of The Irrigation and Drainage Division, American Society of Civil Engineers, pages 115 through 134, June, 1977. Table 1, giving threshold salinity values is presented on pages 122 through 125. (ii) The Maas and Hoffman
publication is on file and available for inspection at the Surface Mining and Reclamation Division Office, Railroad Commission of Texas, 1701 N. Congress Avenue, Austin, Texas 78711; (B) potential increases in the concentration of total dissolved solids of waters supplied to an alluvial valley floor in excess of those specified by Maas and Hoffman shall not be allowed unless the applicant demonstrates, through testing related to the production of crops grown in the locality, that the proposed operations will not cause increases that will result in crop yield decreases; (C) for types of vegetation not listed in Maas and Hoffman as specified by the Commission, based upon consideration of observed correlation between total dissolved solids concentrations in water and crop yield declines, taking into account the accuracy of the correlations; (D) potential increases in the average depth to water-saturated zones (during the growing
season) located within the root zone of the alluvial valley floor that would reduce the amount of subirrigation land compared to pre-mining conditions; (E) potential decrease in surface flows that would reduce the amount of irrigable land compared to pre-mining conditions; and (F) potential changes in the surface- or ground-water systems that reduce the area available to agriculture as a result of flooding or increased saturation of the root zone. (4) For the purposes of this subsection, a farm is one or more land units on which agricultural activities are conducted. A farm is generally considered to be the combination of land units with acreage and boundaries in existence prior to August 3, 1977, or, if established after August 3, 1977, with those boundaries based on enhancement of the farm's agricultural productivity and not related to surface coal mining operations.