Under the 1977 amendments to the Clean Water Act, the Environmental Protection Agency is required to compile a list of priority toxic pollutants and to establish toxic pollutant effluent standards. A list of 126 key water pollutants was produced by EPA in 1981, and is updated regularly, with the updates appearing in the Code of Federal Regulations. This list, consisting of metals and organic compounds and known as the Priority Toxic Pollutant list, also prescribes numerical water quality standards for each compound. State water quality programs must use these standards or develop their own standards of at least equal stringency.