---
kind: "section"
citation: "40 C.F.R. § 125.121"
title: "40"
number: "125.121"
heading: "Definitions."
url: "https://uscodex.org/cfr/40/125.121"
---

# §125.121. Definitions.

- (a) Irreparable harm means significant undesirable effects occurring after the date of permit issuance which will not be reversed after cessation or modification of the discharge.
- (b) Marine environment means that territorial seas, the contiguous zone and the oceans.
- (c) Mixing zone means the zone extending from the sea's surface to seabed and extending laterally to a distance of 100 meters in all directions from the discharge point(s) or to the boundary of the zone of initial dilution as calculated by a plume model approved by the director, whichever is greater, unless the director determines that the more restrictive mixing zone or another definition of the mixing zone is more appropriate for a specific discharge.
- (d) **No reasonable alternatives—** means:
  - (1) No land-based disposal sites, discharge point(s) within internal waters, or approved ocean dumping sites within a reasonable distance of the site of the proposed discharge the use of which would not cause unwarranted economic impacts on the discharger, or, notwithstanding the availability of such sites,
  - (2) On-site disposal is environmentally preferable to other alternative means of disposal after consideration of:
    - (i) The relative environmental harm of disposal on-site, in disposal sites located on land, from discharge point(s) within internal waters, or in approved ocean dumping sites, and
    - (ii) **The risk to the environment and human safety posed by the transportation of the pollutants.**
- (e) **Unreasonable degradation of the marine environment—** means: (1) Significant adverse changes in ecosystem diversity, productivity and stability of the biological community within the area of discharge and surrounding biological communities,
  - (2) Threat to human health through direct exposure to pollutants or through consumption of exposed aquatic organisms, or
  - (3) Loss of esthetic, recreational, scientific or economic values which is unreasonable in relation to the benefit derived from the discharge.

## Notes

### Source

Source: 45 FR 65953, Oct. 3, 1980, 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.