Toxicity testing provides an estimation of the prevailing hazards associated with the water quality of potentially harmful effluents prior to release. It also reflects residual toxicity hazard within receiving water bodies.
The WET (Whole Effluent Test) approach is used, implying that a complex mix of chemical contributes is tested as a whole to reflect the combined hazard/risk, regardless of individual variable compliances. This approach is also referred to as the DEEEP (Direct Estimation of Effect Potential) as prescribed by the Department of Water and Sanitation (DWS).
Results incorporate different trophic levels and give a single easily understandable hazard class for any water source. The fact that different trophic levels are used therefore reflect the hazard to the receiving ecology as a whole.
Results (from definitive testing) can be used to determine safe dilution factors should release or spillage occurs. It is therefore, a strong management tool for environmental managers.
Toxicity testing enables water managers to prioritise the deleteriousness of potential effluents. This helps to decide when to discharge certain water types in accordance with a water use licence and when to contain potentially polluted water types.
Toxicity is a useful surrogate to traditional biomonitoring (macro-invertebrates and fish) analyses at stream sites, especially if flow/habitat conditions are unsuitable for the application of SASS5 (macro-invertebrate) and FAII (fish) monitoring protocols.