Agriculture

(a) General. The surface waters of the state shall be maintained so that toxicity does not inhibit continued ingestion by livestock or irrigation of crops. (b) Definitions. The following words and terms, when used in this Section, shall have the following meaning unless the context clearly indicates otherwise: (1) "Long-term average concentration" means the arithmetic mean of at least ten samples taken across at least twelve months. (2) "Short-term average concentration" means the arithmetic mean of all samples taken during any 30-day period. (c) Subcategories of the Agriculture beneficial use. 18 (1) The narrative and numerical criteria stated or referenced in this section and in Appendix F of this chapter are designed to maintain and protect the beneficial use classification of "Agriculture". This classification encompasses two subcategories which are capable of sustaining different agricultural applications. These subcategories are Irrigation Agriculture and Livestock Agriculture. (2) Irrigation Agriculture means a subcategory of the Agriculture beneficial use requiring water quality conditions that are dictated by individual crop tolerances. (3) Livestock Agriculture is a subcategory of the Agriculture beneficial use requiring much less stringent protection than crop irrigation. (4) If a waterbody is designated in Appendix A of this Chapter with the Agriculture beneficial use but does not have a designation of a subcategory thereof, the criteria for Irrigation Agriculture shall be applicable. (d) Highly saline water. Highly saline water should be used with best management practices as outlined in "Diagnosis and Reclamation of Saline Soils," United States Department of Agriculture Handbook No. 60 (1958). (e) General criteria for the protection of Irrigation Agriculture. This subsection prescribes general criteria to protect the Irrigation Agriculture subcategory. For chlorides, sulfates and total dissolved solids at 180 °C (see Standard Methods), the arithmetic mean of the concentration of the samples taken for a year in a particular segment shall not exceed the historical "yearly mean standard" determined from the table in Appendix F of this Chapter. For permitting purposes, the long-term average concentration shall not exceed the yearly mean standard. Yearly mean standards shall be implemented by the permitting authority using the greater of 1.47 cfs or long-term average flows and complete mixing of effluent and receiving water. For permitting purposes, the short term average concentration shall not exceed the sample standard. Sample standards shall be implemented by the permitting authority using the greater of 1.0 cfs or short term average flows and complete mixing of effluent and receiving water. The data from sampling stations in each segment are averaged, and the mean chloride, sulfate, and total dissolved solids at 180 °C are presented in Appendix F of this Chapter. Segment averages shall be used unless more appropriate data are available. (f) Historic concentrations. The table in Appendix F of this Chapter contains statistical values from historical water quality data of mineral constituents. In cases where mineral content varies within a segment, the most pertinent data available should be used. (g) Criteria to protect Irrigation Agriculture subcategory. For the purpose of protecting the Irrigation Agriculture subcategory, neither long-term average concentrations nor short term average concentrations of minerals shall be required to be less than 700 mg/L for TDS, nor less than 250 mg/L for either chlorides or sulfates. (h) Criteria to protect Livestock Agriculture subcategory. For the purpose of protecting the Livestock Agriculture subcategory, neither long-term average concentrations nor short term average concentrations of minerals shall be required to be less than 2500 mg/L for TDS. (i) Support tests. For purposes of assessment, listing and reporting under sections 303(d) and 305(b) of the federal Clean Water Act as amended, the procedure for determining use support of the Agriculture beneficial use or any subcategory thereof with respect to TDS, chlorides and sulfates shall be as follows: (1) The Agriculture beneficial use designated for a waterbody shall be deemed to be fully supported with respect to TDS or chlorides or sulfates if both the mean of all sample concentrations calculated for that parameter from that waterbody do not exceed the yearly mean standard prescribed in OAC 252:730 Appendix F or site specific criteria prescribed in OAC 252:730 Appendix E, and no more than 10% of the sample concentrations from that 19 waterbody exceed the sample standard prescribed in OAC 252:730 Appendix F or site specific criteria prescribed in OAC 252:730 Appendix E. (2) The Agriculture beneficial use designated for a waterbody shall be deemed to be not supported with respect to TDS or chlorides or sulfates if either the mean of all sample concentrations calculated for that parameter from that waterbody exceeds the yearly mean standard prescribed in OAC 252:730 Appendix F or site specific criteria prescribed in OAC 252:730 Appendix E, or greater than 10% of the sample concentrations from that waterbody exceed the sample standard prescribed in Appendix F or site specific criteria prescribed in OAC 252:730 Appendix E. Provided, if the sample concentrations are each less than 700 mg/L for TDS, or less than 250 mg/L for either chlorides or sulfates, then the Agriculture beneficial use shall be deemed to be fully supported for that parameter. 252:730-5-14 [RESERVED] 252:730-5-15 [RESERVED]