Indicator 2.7.3

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System

Water Type

Feed Dependent

Species

Indicator 2.7.3

by Contact on 8 October 2026

Requirement

The UoC shall only discharge effluent water of a salinity level equal to or lower than the salinity level of the receiving waterbody or natural wetland. An exception applies to waterbodies and natural wetlands that have naturally periodic varying salinity levels, in which case the salinity level of the effluent water shall be within range of the natural variation.

How Do I Interpret This Requirement?

  • Salinity levels are: Freshwater (limnetic; <0.5 ppt), slightly saline (oligohaline; 0.5-4.9 ppt), moderate saline (mesohaline; 5-17.9 ppt), highly saline (polyhaline; 18-29.9 ppt) and seawater (euhaline; 30-34.9 ppt).

  • River estuaries are an example of a waterbody that have periodic varying salinity levels. These can also be referred to as poikilohaline waterbodies.

  • Salinity testing of effluent water in the receiving waterbody or natural wetlands should be conducted.

  • Salinity levels in the receiving waterbody or natural wetlands may be obtained from credible sources, e.g. results of government monitoring.

  • To comply with the exception in the indicator, salinity testing in the waterbody or natural wetland should take place. Alternatively, test results can be obtained from credible sources, e.g. scientific or government body.

    • Results should then be compared to the salinity level of the effluent water to determine whether it is within the range of natural variation for the receiving waterbody or natural wetlands.

Evidence of Implementation

  • Results of salinity testing for effluent water and in the receiving waterbody or natural wetlands.

  • If applicable, reports or measurements determining whether waterbodies and natural wetlands have naturally varying salinity levels.

    • Reports or measurements determining whether the salinity level of the effluent water is within the range of the natural variation for the receiving waterbody or natural wetlands.

Auditors Should Confirm

  • Salinity test results have been presented which determine one of the following:

    • Salinity level of the effluent water is equal to or lower than the salinity level of the receiving waterbody or natural wetlands.

    • Salinity level of the effluent water is within the range of natural variation for the receiving waterbody or natural wetlands that have naturally varying salinity levels.