Effluent guidelines

Effluent Guidelines (also referred to as Effluent Limitation Guidelines (ELGs)) are U.S. national standards for wastewater discharges to surface waters and publicly owned treatment works (POTW) (also called municipal sewage treatment plants). The United States Environmental Protection Agency (EPA) issues Effluent Guideline regulations for categories of industrial sources of water pollution under Title III of the Clean Water Act (CWA). The standards are technology-based, i.e. they are based on the performance of treatment and control technologies (e.g., Best Available Technology). Effluent Guidelines are not based on risk or impacts of pollutants upon receiving waters.

Since the mid-1970s, EPA has promulgated ELGs for 59 industrial categories, with over 450 subcategories. Effluent Guidelines currently control pollution at approximately 40,000 facilities that discharge directly to the nation's waters, 129,000 facilities that discharge to POTWs, and construction sites. Effluent Guidelines are implemented in water discharge permits issued to facilities through the National Pollutant Discharge Elimination System (NPDES).

Overview
Regulated pollutants vary by industry category, with effluent limitations typically expressed as mass loadings or concentrations. The regulations cover pollutants for which there are approved analytical testing methods. EPA has published many methods in its regulations, and has approved the use of other methods published by peer-reviewed sources, such as Standard Methods. Although the effluent limitations are based on the performance of control and treatment technologies (and not the impacts to receiving waters), the regulations do not require discharging facilities to use specific technologies. The facilities may choose any technologies to meet the numerical limitations.

In the 1972 CWA Congress specified an initial list of categorical regulations that EPA was required to promulgate. The 1977 CWA amendments provided a list of pollutant and pollutant groups to be considered by the agency in developing regulations. EPA is also required to review and revise regulations as needed, and since 1972 it has promulgated ELGs for 59 industrial categories, with over 450 subcategories. Approximately 40,000 facilities that discharge directly to the nation's waters, 129,000 facilities that discharge to POTWs, and construction sites, are covered by the regulations. The regulations annually prohibit the discharge of 700 billion pounds of pollutants into U.S. surface waters.

The effluent limitations for the Construction and Development category are narrative in format and do not specify numeric pollutant limits. The requirements consist of erosion controls and sediment controls, soil stabilization practices and pollution prevention practices (such as minimizing exposure of building materials, pesticides and other chemicals).

In the early years of the program (1970s-1980s) the agency published analytical methods for a list of 126 "priority pollutants," consisting of various toxic pollutants. Subsequently the agency has issued methods and regulated pollutants beyond those in the initial priority list.

Facilities that directly discharge to "waters of the United States" are required to obtain NPDES permits, and effluent guideline requirements are incorporated into these permits. Indirect dischargers (i.e. facilities discharging to POTWs) are subject to effluent guideline requirements called "Pretreatment Standards."

Existing regulations
This table lists the 59 Effluent Guidelines categories published by EPA.

Program plans
EPA periodically publishes a list of ongoing and new regulation projects, and a list of categories that it is considering for regulation, in its "Effluent Guidelines Program Plan." Program Plan 15, published in January 2023, announced several regulatory and research projects. According to the agency's "PFAS Strategic Roadmap", it is continuing to evaluate options to reduce discharges of per- and polyfluoroalkyl substances (PFAS) from a variety of industrial sectors. In this regard EPA has decided that changes to the Landfills regulation (40 CFR part 445) are necessary, to address discharges of PFAS from landfill leachate.

EPA will conduct research on the Textile Mills category (40 CFR part 410) to learn more about its PFAS usage and discharge characteristics. The agency will study PFAS discharged to POTWs by various industries, including categories that have recently been examined. EPA intends to confirm the origins of PFAS wastewater and assist POTWs in determining whether source-level controls are necessary. The Concentrated Animal Feeding Operations Category (40 CFR part 412) will also be investigated. The POTW influent study will include monitoring of the Electrical and Electronic Components Category (40 CFR part 469) for PFAS discharge data even though EPA is not currently seeking additional action for this category. Additionally, EPA will keep an eye on PFAS use and emissions from airports and the Pulp, Paper, and Paperboard Category (40 CFR part 430).