CFR›Title 40›Chapter I›Part 131›Subpart C ContainsSections 131.20–131.22CorpusDaily eCFRDisplayed edition2026-07-06Last updated2026-07-06 Subpart C—Procedures for Review and Revision of Water Quality Standards Sections 131.20 § 131.20 State review and revision of water quality standards. 131.21 § 131.21 EPA review and approval of water quality standards. 131.22 § 131.22 EPA promulgation of water quality standards. Previous B Subpart B—Establishment of Water Quality Standards Next D Subpart D—Federally Promulgated Water Quality Standards