Although models are essential tools if regulators are to be able to predict the risks or the effects of their regulations on the natural and human environment, models are neither necessary nor sufficient to produce the regulations themselves. In the 1970s, when the legislative framework underlying most of today’s environmental policy was first established, few sophisticated computational environmental models—models designed to predict the environmental consequences of human activity—existed. Moreover, the monitoring networks capable of quantitative description of the state of the environment were rudimentary, and the technology for measurement of pollutant discharges of various kinds and their environmental effects were much less developed than today’s technology. It was in this setting that most modern environmental regulatory statutes first appeared, including the Clean Air Act (CAA) of 1967, the Federal Water Pollution Control Act of 1972 and renamed the Clean Water Act (CWA) in 1977, and the Safe Drinking Water Act of 1976. Regulatory designs at the time necessarily minimized the use of computational models in the regulatory process.
The models that did exist played little role in that process because the new environmental statutes emphasized the use of technology-based pollution discharge regulation. Technology-based regulation requires polluters to adopt a particular technology (or, in some cases, achieve a level of performance associated with a particular technology) without regard to the potential or actual environmental improvements that would result.
Even before the implementation of the federal environmental statutes, technology-based regulation partly relied on there being some level of pollution abatement practiced by at least some plants in most industries. EPA was to find those plants and set a performance standard for all plants that was based in some way on what most plants were doing. Usually the congressional mandate involved the use of the words “best technology,” and it was left to EPA to interpret and give operational meaning to the various designations of “best.” For example, industrial water pollutant dischargers had to meet “best practicable treatment” (BPT) technology standards by 1977 and “best available treatment economically achievable” (BATEA or, more often, BAT) standards by 1983. In industries such as food processing and laundries that generated wastewater that resembled domestic waste (in constituents if not in strength), the usual interpretation of BPT was a performance standard that approximated what good secondary (biological) treatment could do. For other