On November 12, 2021, MassDEP promulgated amendments to the Massachusetts Surface Water Quality Standards (the SWQS), 314 CMR 4.00. Subsequently, MassDEP published two sets of corrections, effective December 10, 2021 and January 7, 2022. MassDEP has posted an unofficial version of the regulation as amended and corrected online, which is now enforceable by the Commonwealth. However, federal Water Quality Standards regulations promulgated at 40 Code of Federal Regulations Part 131, 40 CFR 131, pursuant to the federal Clean Water Act (CWA), 33 USC 1251 et seq., require that state water quality standards be approved by the U.S. Environmental Protection Agency (EPA) to be federally enforceable for CWA purposes such as water quality assessments, total maximum daily loads, and National Pollutant Discharge Elimination System permits. On March 31, 2022, EPA approved the majority of the amendments to the SWQS, disapproved six amendments, and deferred action on others. Additional information on the status of the amendments to the SWQS is available here.