---
kind: "section"
citation: "40 C.F.R. § 125.61"
title: "40"
number: "125.61"
heading: "Existence of and compliance with applicable water quality standards."
url: "https://uscodex.org/cfr/40/125.61"
---

# §125.61. Existence of and compliance with applicable water quality standards.

- (a) There must exist a water quality standard or standards applicable to the pollutant(s) for which a [section 301(h)](/cfr/40/301.md?p=h) modified permit is requested, including:
  - (1) Water quality standards for biochemical oxygen demand or dissolved oxygen;
  - (2) Water quality standards for suspended solids, turbidity, light transmission, light scattering, or maintenance of the euphotic zone; and
  - (3) **Water quality standards for pH.**
- (b) **The applicant must—**
  - (1) Demonstrate that the modified discharge will comply with the above water quality standard(s); and
  - (2) Provide a determination signed by the State or interstate agency(s) authorized to provide certification under §§ [124.53](/cfr/40/124.53.md) and [124.54](/cfr/40/124.54.md) that the proposed modified discharge will comply with applicable provisions of State law including water quality standards. This determination shall include a discussion of the basis for the conclusion reached.

## Notes

### Authority

Authority: Clean Water Act, as amended by the Clean Water Act of 1977, 33 U.S.C. 1251 et seq., unless otherwise noted.

### Source

Source: 59 FR 40658, Aug. 9, 1994, unless otherwise noted.

### Authority

Authority: The Clean Water Act, 33 U.S.C. 1251 et seq., unless otherwise noted.

### Source

Source: 44 FR 32948, June 7, 1979, unless otherwise noted.