Development and use of water quality criteria and standards in the United States

Water quality criteria, as a means of disinguishing "good" water from "bad" water, have been employed for over 150 years. During the 1940s and 1950s, the formulation of water quality criteria and their role in water quality management were hotly debated in the United States as each state formulated its own approach to water pollution control. In 1965, when the federal government assumed control of water quality management in the US, a single, national approach to the formulation and use of criteria had to be selected and implemented nationwide. The purpose of this paper is to briefly review the history of criteria as a basis for water quality management in the US; note the different water quality management philosophies used by states prior to 1965; and summarize the relationship of criteria to monitoring over the past 30 years. Standards, as legal instruments, are developed for specific water body by designating a use of the water (society value) and the criteria necessary to protect the use (a scientific finding). Standard violation, as a concept, tends to remain as a single-sample exercise (i.e., the sample measurement is either above or below the standard). Increasingly, however, there is a demand to classify large bodies of water (e.g., lake, river segment, or aquifer), over a set time period, such as a day, year, or decade, as either in compliance or in violation of water quality standards. No peer-reviewed, standardized method for computing standard "violations" has been widely accepted for this purpose. The paper ends with a call to develop such methods if water quality managers must produce standard violation information (infer sample results) over time and space.