PART 131—WATER QUALITY STANDARDS
- Subpart A—General Provisions (§§ 131.1 - 131.8)
- Subpart B—Establishment of Water Quality Standards (§§ 131.9 - 131.15)
- Subpart C—Procedures for Review and Revision of Water Quality Standards (§§ 131.20 - 131.22)
- Subpart D—Federally Promulgated Water Quality Standards (§§ 131.31 - 131.47)