PART 131—WATER QUALITY STANDARDS
- SUBPART A—General Provisions (§131.1 to §131.8)
- SUBPART B—Establishment of Water Quality Standards (§131.10 to §131.13)
- SUBPART C—Procedures for Review and Revision of Water Quality Standards (§131.20 to §131.22)
- SUBPART D—Federally Promulgated Water Quality Standards (§131.31 to §131.42)