---
kind: "unit"
title: "40"
title_heading: "Protection of Environment"
key: "chI/subchD/part125"
level: "part"
label: "Part 125"
heading: "Criteria and Standards for the National Pollutant Discharge Elimination System"
release: "ecfr-current"
date: "2026-08-27"
url: "https://uscodex.org/cfr/40/chI-subchD-part125"
sections_count: 60
---

# Part 125 — Criteria and Standards for the National Pollutant Discharge Elimination System

Title 40 C.F.R. — Protection of Environment › Chapter I — Environmental Protection Agency › Subchapter D — Water Programs

## Contents

- [Subpart A — Criteria and Standards for Imposing Technology-Based Treatment Requirements Under Sections 301(b) and 402 of the Act](/cfr/40/chI-subchD-part125-subpartA.md)
- [Subpart B — Criteria for Issuance of Permits to Aquaculture Projects](/cfr/40/chI-subchD-part125-subpartB.md)
- [Subpart C — Subpart C [Reserved]](/cfr/40/chI-subchD-part125-subpartC.md)
- [Subpart D — Criteria and Standards for Determining Fundamentally Different Factors Under Sections 301(b)(1)(A), 301(b)(2) (A) and (E) of the Act](/cfr/40/chI-subchD-part125-subpartD.md)
- [Subpart E — Criteria for Granting Economic Variances From Best Available Technology Economically Achievable Under Section 301(c) of the Act [Reserved]](/cfr/40/chI-subchD-part125-subpartE.md)
- [Subpart F — Criteria for Granting Water Quality Related Variances Under Section 301(g) of the Act [Reserved]](/cfr/40/chI-subchD-part125-subpartF.md)
- [Subpart G — Criteria for Modifying the Secondary Treatment Requirements Under Section 301(h) of the Clean Water Act](/cfr/40/chI-subchD-part125-subpartG.md)
- [Subpart H — Criteria for Determining Alternative Effluent Limitations Under Section 316(a) of the Act](/cfr/40/chI-subchD-part125-subpartH.md)
- [Subpart I — Requirements Applicable to Cooling Water Intake Structures for New Facilities Under Section 316(b) of the Act](/cfr/40/chI-subchD-part125-subpartI.md)
- [Subpart J — Requirements Applicable to Cooling Water Intake Structures for Existing Facilities Under Section 316(b) of the Clean Water Act](/cfr/40/chI-subchD-part125-subpartJ.md)
- [Subpart K — Subpart K [Reserved]](/cfr/40/chI-subchD-part125-subpartK.md)
- [Subpart L — Criteria and Standards for Imposing Conditions for the Disposal of Sewage Sludge Under Section 405 of the Act [Reserved]](/cfr/40/chI-subchD-part125-subpartL.md)
- [Subpart M — Ocean Discharge Criteria](/cfr/40/chI-subchD-part125-subpartM.md)
- [Subpart N — Requirements Applicable to Cooling Water Intake Structures for New Offshore Oil and Gas Extraction Facilities Under Section 316(b) of the Act](/cfr/40/chI-subchD-part125-subpartN.md)