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3.2. Clean Water Act

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Under the Clean Water Act (33 U.S.C. 1251), EPA’s principal rulemaking activity is to establish effluent limitation guidelines for industrial and municipal waste-water treatment facilities. The CWA specifies that these guidelines are to be technology based; however in deciding which of many technologies is appropriate costs and effluent reduction benefits should be taken into account. While non-water quality environmental impacts are to be considered when setting the guidelines, the benefits of water-quality improvements are not mentioned specifically as factors to be considered. The CWA does provide that more stringent water-quality-based effluent limitations are to be imposed for individual facilities when necessary to meet state water-quality standards.

For point source dischargers other than Publicly Owned Treatment Works (POTWs), EPA is to set effluent limitation guidelines that require "best practicable technology currently available" (BPT). EPA interprets BPT to mean the "average of the best existing performance by well-operated plants within each industrial category." Section 1314 states that in setting BPT standards, the Administrator of EPA should consider the total cost of using the technology in relation to the effluent reduction benefits to be achieved and also consider the age of equipment, the processes used, non-water quality impacts (including energy requirements), and other factors the Administrator deems important.

Certain industrial source categories are subject to more stringent effluent limitations requiring the best available technology economically achievable (BAT). Generally BAT requirements apply to toxic pollutants and a few nonconventional pollutants such as ammonia, chlorine, iron and phenols. BAT was defined by the EPA as the "very best control and treatment that have been or are capable of being achieved." In setting BAT standards, EPA is required to consider the age of the equipment at the facilities involved, the processes employed, the cost of achieving effluent reductions, non-water quality environmental impacts and other factors as the Administrator deems important. There is no consideration of cost in relation to effluent reduction benefits as is the case for BPT standards.

Conventional pollutants, which were the focus of the 1970 Clean Water Act, are excluded from the scope of BAT standards. For these parameters (biochemical oxygen demand, suspended solids, pH, fecal coliform, grease and oil), the 1977 Amendments to the CWA created a new standard: Best Conventional Pollutant Control Technology (BCT). In setting BCT standards EPA is required to consider the reasonableness of the relationship between the costs of attaining a reduction in effluents and the effluent reduction benefits, to compare the cost and level of reduction of pollutants from the discharge from a POTW to the cost and level of reduction achieved from industrial sources, and to take into account the age of equipment and facilities involved, the processes employed, non-water quality environmental impacts and other factors as the Administrator deems important.

Point sources that discharge to a POTW are termed indirect dischargers. For indirect dischargers, the Act directs EPA to set pretreatment guidelines for existing sources (PSES) and pretreatment guidelines for new sources (PSNS). The guidelines are to control and prevent indirect and direct discharges of any pollutant that interferes with or is otherwise incompatible with the operation of a POTW.

New sources, which are defined as sources whose construction commenced after applicable effluent guidelines for the sector were published, must comply with New Source Performance Standards (NSPS). Such standards must seek the greatest degree of effluent reduction achievable through best available demonstrated technology, including changes in process and operating methods. Economic cost is one criterion that EPA must consider but the benefits of water quality improvement are not.

Section 1298 calls for cost-effective treatment of wastes from publicly owned treatment plants (POTW). Federal financial assistance to states, municipalities, or interstate agencies for waste treatment systems must be for approaches that are the "most economical and cost-effective" to meet the requirements of the Clean Water Act. The standards for publicly owned treatment works are to be set to achieve “the degree of effluent reduction available through the application of secondary treatment.” Thus, for POTWs the Act requires the equivalent of secondary treatment but done in the most cost-effective way.

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