---
kind: "unit"
title: "40"
title_heading: "Protection of Environment"
key: "chI/subchD/part123"
level: "part"
label: "Part 123"
heading: "State Program Requirements"
release: "ecfr-current"
date: "2026-08-27"
url: "https://uscodex.org/cfr/40/chI-subchD-part123"
sections_count: 29
---

# Part 123 — State Program Requirements

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

## Contents

- [Subpart A — General](/cfr/40/chI-subchD-part123-subpartA.md)
- [Subpart B — State Program Submissions](/cfr/40/chI-subchD-part123-subpartB.md)
- [Subpart C — Transfer of Information and Permit Review](/cfr/40/chI-subchD-part123-subpartC.md)
- [Subpart D — Program Approval, Revision, and Withdrawal](/cfr/40/chI-subchD-part123-subpartD.md)