Requirements specific to agriculture criteria

(a) Historical data. If defensible site-specific background analytical data is not available, DEQ will use the YMS and SS criteria in OAC 252:730, Appendix F, to determine the background concentrations of the mineral constituents. In the absence of listed YMS and SS criteria specific to the receiving water of interest, the segment averaged YMS and SS criteria are used to establish the background concentrations of the mineral constituents. CB is calculated according to Equation I-11in Appendix I. (b) Site-specific background data available. Where a site-specific background data set of at least ten data points is available, DEQ may use the arithmetic average of the site-specific background data set instead of a background level determined from the segment-averaged YMS and SS values in OAC 252:730, Appendix F. (c) Background monitoring. Where agriculture criteria-based limitations are established in a permit, DEQ may require background monitoring of the limited mineral constituent(s) to determine site-specific conditions.