Assessing a waste discharge

You can use the Water Quality Management Framework and associated monitoring data to assess compliance or any current or potential impacts of a waste discharge on water/sediment quality. Assessing a waste discharge in this way aims to ensure that it complies with the conditions of approval and is not causing environmental harm.

You may want to assess if there is evidence for existing or potential environmental harm that may not be currently detected. Such as when waste discharges are unregulated. Or licence conditions do not reflect the risks associated with the current discharge and may not reflect leading practice.

Collected monitoring or assessment data are used to refine or improve system understanding, indicators, measurement programs, water/sediment quality guideline values and water/sediment quality objectives. Monitoring and assessment advice is provided at key steps in the Water Quality Management Framework.

See also:

Expand a​ll

Use current understanding to develop or refine a conceptual model of key waterway processes and how the waste discharge could affect local waterways. This will inform your decisions at subsequent steps in the framework.

Typically, the operator of the discharge will undertake this step, possibly in consultation with the regulator and some stakeholder involvement.

You will need:

  • existing data and literature from the baseline, an environmental impact assessment or a project application for an existing discharge
  • site-specific information on the operation and receiving environment (e.g. current water quality and temporal and spatial release characteristics of the discharge, mixing zones and regulatory compliance points, water quality and ecology of the receiving environment).

In most cases, you can obtain existing information sources for this process, even for a new discharge. But you may need to collect new baseline data.

As further monitoring data become available, update and refine the current understanding.

Use the conceptual model at Step 3 to identify key indicators for key pressures, stressors and ecosystem receptors selected for the multiple lines-of-evidence process for assessing and managing water/sediment quality. These indicators will be used to assess compliance or water/sediment quality impacts of the waste discharge.

Key concepts:

The regulator will commonly develop ​ community values and more specific management goals (including level of protection) for relevant waterways and incorporate them into any waste discharge licence conditions.

For unregulated discharges or outdated licence conditions, operators may develop their own internal management goals, with stakeholder involvement as necessary. The regulator will endorse a process for this to occur.

Management goals should be updated as more information becomes available. More commonly, negotiations to alter management goals occur separately to the monitoring and assessment cycle, and may lag behind the improvement of current understanding gained from monitoring and assessing the waste discharge.

Key concepts:

Select a mix of indicators for the relevant pressures identified in the waterway (e.g. waste discharge), their associated stressors (e.g. relevant contaminants) and anticipated ecosystem receptors. This is consistent with using multiple lines of evidence in a weight-of-evidence process for assessing and managing water/sediment quality.

Development or refinement of the conceptual models, community values and management goals at Steps 1 and 2 forms the basis of the indicator selection.

We provide use-specific quality of evidence tables to assist with the selection of different lines of evidence and their indicators.

Indicator selection may be influenced by the regulator’s default preferences for indicator consistency for waterways or activities of a similar type.

You may commence or continue monitoring at this step to:

  • establish or add to baseline data
  • test and validate relevant indicators
  • refine associated sampling methodologies (e.g. associated hazard assessment for physical and chemical parameters).

Initial monitoring data may cause you to further refine the list of selected indicators, such as where monitoring for an indicator at the required level of sensitivity is found to be impractical.

You can use initial monitoring data to assess water/sediment quality (at Step 6) but you will need to account for site suitability (e.g. spatial and temporal dynamics of water quality to define mixing zones and compliance points).

Key concepts:

In consultation with the regulator, determine the water/sediment quality guideline values for each of the biological, chemical and physical indicators that will provide the desired level of protection (if applicable) for your management goals and the protection of identified community values. (Sometimes the guideline values can be determined by the regulator.)

Where possible, derive or use locally relevant (e.g. site-specific, catchment) guideline values based on local monitoring data or biological-effects data. Until these are available, use the default guideline values (DGVs) but be aware that they may not represent your local system.

If possible, establish or continue monitoring programs to derive locally relevant guideline values.

Key concepts:

To define the draft water quality objectives (or sediment quality objectives), select the guideline values and/or narrative statements at Step 4 for each selected indicator at Step 3 that should ensure the protection of all identified community values and their management goals (Step 2). Choose the most stringent of the guideline values for the water/sediment quality objectives (W/SQOs).

Take into any account existing catchment or regional W/SQOs established by the regulator or in any relevant water quality management plans. Draft W/SQOs are typically proposed as draft compliance limits.

At this stage, these are aspirational objectives that have not yet accounted for cultural, economic and social considerations (at Step 8).

Key concept:

Compare the current water/sediment quality monitoring data for each relevant indicator with the water/sediment quality objectives (W/SQOs), together with the evidence from any additional lines of evidence. In the case of a waste discharge licence, this would typically be applied at the edge of an agreed mixing zone or at sampling locations specified in the licence.

Use the results to assess water/sediment quality, including:

  • whether or not the W/SQOs have been met
  • the cause and spatial extent of any change observed (where applicable).

Use a weight-of-evidence process to evaluate the various lines of evidence. This process assesses results from multiple lines of evidence across the pressures, stressors and ecosystem receptors relevant to the waste discharge. It is the key process by which the protection of community values is assessed.

Multiple potential outcomes are possible from a weight-of-evidence evaluation. We provide guidance on their interpretation for this use of the Water Quality Management Framework in use​-specific evaluation tables.

The resulting evaluation of current water/sediment quality will usually include classifying the waterways potentially impacted by the waste discharge as:

  • those that meet the W/SQOs
  • those that do not meet the W/SQOs or for which adverse trends are evident
  • those for which the outcome is uncertain.

The W/SQOs are deemed to be met when:

  • those lines of evidence considered as essential for informing acceptable water/sediment quality are met
  • results for other supporting lines of evidence are consistent with no compromise to current or future water/sediment quality.

If the W/SQOs are met, then management should focus on maintaining or improving current water/sediment quality. This will require a check of any possible improvements to management strategies at Step 8, confirmation of meeting the W/SQOs at Step 9, and then implementation at Step 10.

A weight-of-evidence evaluation will otherwise conclude that:

  • W/SQOs are not met
  • adverse trends are evident
  • result is inconclusive (e.g. due to difficulties in obtaining sufficient good quality monitoring data or if there is conflicting evidence from separate lines of evidence).

In these cases, up to 3 options are available:

  • formulate, assess and prioritise management strategies to improve existing water/sediment quality associated with the waste discharge (Steps 8 to 10), and/or
  • reassess the appropriateness of the water/sediment quality guideline values (Step 7), and/or
  • consider selection of additional or alternative indicators or lines of evidence (Step 7).

Key concepts:

At this step we typically identify the need to:

  • include additional relevant lines of evidence and associated indicators via Step 3, or
  • improve the water/sediment quality guideline values via Steps 4 and 5.

Additional relevant lines of evidence and associated indicators would be required if the weight-of-evidence evaluation at Step 6 showed:

  • insufficient lines of evidence to make an evaluation of suitable quality, or
  • one or more of the selected indicators proved impractical to implement, or failed to provide evidence of sufficient certainty or sensitivity.
  • Water/sediment quality guideline values (Step 4), and hence objectives (Step 5), may need to be refined where existing objectives are not locally relevant (e.g. overly conservative). This might be relevant where a waste discharge licence is still in negotiation and final objectives have not yet been agreed.

Studies required to refine water/sediment quality objectives or include additional lines of evidence at this step may not necessarily be lengthy, and may include:

  • implementing additional monitoring
  • continuation or refinement of existing monitoring
  • dedicated laboratory or field-effects studies, to establish more relevant indicators or water quality guideline values.

Completing this step would usually require the operator undertaking the work and presenting it to the regulator and other stakeholders for consideration. Work associated with this step would often be done in the lead-up to licence negotiations for both new and expiring licences.

In practice, Steps 7 and 8 are likely to be conducted in parallel, largely by the operator in consultation with the regulator.

Key concepts:

Even if the water/sediment quality objectives (W/SQOs) were met, before progressing to Step 10 you can consider options for continual improvement of the management strategies to improve water/sediment quality.

You may need to reconsider existing management strategies and consider alternative strategies for the waste discharge (e.g. water treatment, actively managed discharge) if the evaluation at Step 6 indicated that:

  • draft or existing W/SQOs had not been met, or
  • water quality was trending towards or indicative of increased risk to community values.

Formulate, assess and prioritise improved and/or alternative management strategies on the basis of environmental considerations, as well as cultural, economic and social considerations (quadruple bottom line).

Agreement on final management strategies will require robust stakeholder involvement. This may need to be supported by:

  • relevant monitoring
  • modelling
  • cultural, economic and social studies
  • multiple objective decision support tools (where possible).

The operator must use monitoring data or appropriate water quality predictive models to demonstrate to the regulator that alternative management strategies for waste discharge management, together with any revised W/SQOs, achieve the required water/sediment quality.

In practice, Steps 7 and 8 are likely to be conducted in parallel, largely by the operator in consultation with the regulator.

Key concepts:

If the water/sediment quality objectives (W/SQOs) have been met — or are expected to be met — by one or more of the management strategies (assessed in Step 8) and are also culturally, economically and socially acceptable, then go to Step 10.
In the case of:

  • draft W/SQOs — these can be finalised, along with the associated waste discharge licence, for implementation at Step 10.
  • existing W/SQOs — this indicates compliance with an existing waste discharge licence.

If the W/SQOs are not achievable (e.g. costs or impacts associated with the necessary improvements to meet the objectives are not acceptable), then you have 2 options:

  • Go back and iterate back through the Water Quality Management Framework to refine the components of the relevant steps. For example:
  • at Step 1, you can improve current understanding based on knowledge gained from monitoring and assessments at Steps 7 and 8
  • at Step 2, you could reconsider the management goals (including level of protection) in consultation with the regulator and some stakeholder involvement. At Step 5, this would then result in a set of incremental W/SQOs that are focused on improvement towards meeting the original management goals in the longer term.
  • In some cases, the waste discharge under consideration may need to be assessed as having unacceptable water/sediment quality consequences and regulatory action may be required.

Key concept:

​You have reached Step 10 because an acceptable water/sediment quality has been or can be achieved.

Implement the agreed management strategy in accordance with a new waste discharge licence or the outcomes of an assessment of an existing waste discharge licence.

A suitable and agreed management strategy includes ongoing and refined monitoring and assessment programs to ensure the continued protection of community values and compliance where required (adaptive management).

Continual improvement of both management, monitoring and reporting activities should be considered at this step and included in the agreed management strategy.

Ongoing management, monitoring and reporting will lead to continued cycling through the Water Quality Management Framework, allowing you to incorporate improvements at all relevant steps based on knowledge gained along the way.

You will need to establish appropriate arrangements for involving and reporting to stakeholders (stakeholder involvement). These would be specified in the waste discharge licence.

Key concepts: