United States Environmental Protection Agency
Effluent Guidelines Program Plan 15
January 2023
Executive Summary
…Finally, Plan 15 announces EPA’s intent to undertake a detailed study of the Concentrated Animal Feeding Operations (CAFOs) Category (40 CFR part 412), which will focus on collecting further information to enable the Agency to make an informed, reasoned decision whether to undertake rulemaking to revise the ELG for CAFOs.

Section 6.2
6.2 Concentrated Animal Feeding Operations Point Source Category (40 CFR part 412)
CAFOs are facilities that confine and maintain large numbers of animals for specified periods of time (40 CFR 122.23 defines CAFOs in precise terms). The CAFOs ELG regulate two parts of CAFOs: the “production area” and the “land application area.” The production area is the area that includes the animal confinement area, manure storage areas, raw materials storage area, and waste containment areas (40 CFR 122.23(b)(8)). The land application area is the land under the control of a CAFO owner or operator to which manure, litter, and process wastewater from the production area is or may be applied (40 CFR 122.23(b)(3)).
The existing CAFOs ELG impose substantial and detailed requirements on both the production area and land application area. The ELG requirements for the production area prohibit the discharge of manure, litter, and process wastewater from the production area to waters of the United States, with only one exception (40 CFR 412.31(a)). Under this exception, the ELG allow discharges from the production area where those discharges are caused by precipitation and where the production area is designed to contain all manure, litter, and process wastewater from a 25-year, 24-hour rainfall event (40 CFR 412.31(a)(1) defines this exemption in precise terms).37
The ELG requirements for the land application area prohibit discharges unless those discharges qualify as “agricultural stormwater,” which the CWA expressly excludes from regulation (33 USC 502(14)). EPA interprets “agricultural stormwater” to include any precipitation-related discharges of manure, litter, and process wastewater from the land application areas if the manure, litter, and process wastewater has been applied to the land application area in accordance with a site-specific “nutrient management plan” that ensures appropriate agricultural utilization of the nutrients in the manure, litter, or process wastewater (40 CFR 122.23(e)). A nutrient management plan addresses the form, source, amount, timing, and method of application of nutrients on each field to achieve crop production goals while minimizing the transport of nutrients to surface waters (40 CFR 412.4(c)(1)). The application rates for manure, litter, and process wastewater must be established in accordance with technical standards established by each state (see 40 CFR 123.36; 412.4(c)(2)). The ELG also require CAFOs to comply with certain recordkeeping and reporting requirements related to both the production area and the land application area (40 CFR 412.4(b), (c)).
EPA has concluded that it needs to gather additional information to inform a decision as to whether rulemaking to revise the ELG is warranted. See Appendix A for discussion of the agency’s rationale for this decision and the information EPA plans to gather as part of its detailed study.
36 See EPA’s April 2022 memorandum and December 2022 memorandum, detailing EPA’s intention to address PFAS discharges in NPDES permits and through the pretreatment program and monitoring programs. In addition to reducing PFAS discharges, this will also provide data to inform ELG planning and actions.
37 The ELG allow CAFOs to request site-specific alternatives to the containment requirements if those alternatives result in discharge amounts that are equal to or less than the containment requirements (40 CFR 412.31(a)(2) defines these alternative requirements in precise terms).