Indicator 2.6.22

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System

Water Type

Feed Dependent

Species

Indicator 2.6.22

by Contact on 8 October 2026

Requirement

Indicator scope: point source systems in waterbody types A and B The UoC shall conduct DO monitoring downstream from the outflow point and shall demonstrate that daily diurnal DO (DDDO) fluctuation is ≤65% saturation, following the method outlined in Appendix 8 (8.11).

How Do I Interpret This Requirement?

  • For UoCs located in tidal systems, timing of measurements should correspond with high and low tides, to reflect variations related to the tidal regime.

  • The UoC can conduct DO monitoring immediately downstream of the last site in a waterbody whilst still following the sampling method in Appendix 8 (8.11).

  • This may reduce sampling costs when there are multiple sites discharging point source effluent releases to a Type B waterbody near each other.

  • The methods outlined in Appendix (8.11.2 and 8.11.3) shall be used to record DO concentrations used to determine daily diurnal DO (DDDO).

  • Any missed samples or deviations in sampling time should be accompanied by a written justification.

Evidence of Implementation

  • Records that DO measurements correspond to high and low tides in tidal systems.

  • The location of the sampling point, demonstrating that measurements have taken place downstream from the outflow point.

  • Results of daily DO monitoring and DDDO fluctuation calculations.

Auditors Should Confirm

  • DO measurements have taken place at high and low tides in tidal systems.

  • DO measurements have taken place downstream from the outflow point.

  • The UoC has presented results of the DDDO calculations based on DO measurements collected in accordance with the methods outlined in Appendix 8.11.1 and 8.11.2.

  • Confirm the fluctuation level based on the DDDO calculation is ≤65% saturation level.

  • Written justifications were provided if there were any missed samples or deviations in the sampling time.