August 12, 2016 by Dean Leverett


Chemical Water Quality Standards for the protection of long-term effects– e.g. Environmental Quality Standards (EQS) in Europe, Water Quality Criteria in the USA, Water Quality Guidelines in Canada - are concentrations of specific substances in water below which effects on the aquatic organisms are not expected to occur. In all jurisdictions that implement such standards (in either a regulatory or aspirational sense), their development generally follows a generic hazard assessment approach in which a Predicted No Effect Concentration (PNEC) is derived using the available ecotoxicology data for a substance.

However, the specific methodologies and techniques applied in deriving the PNEC and the final, implemented standard often differs significantly between different jurisdictions.

Water Quality Standards usually form the basis of environmental protection objectives with respect to chemical contamination in the aquatic environment within a jurisdiction but can take a considerable amount of time and resource to develop. For those standards which are implemented within regulatory regimes, there is usually an addition political aspect to be taken into account, since assessment of compliance with the standards is likely to infer significant burdens on regulatory bodies, industry and governments, in terms of monitoring and potential measures to reduce environmental concentrations. For these and other reasons, there are likely to be some chemicals with the potential to impact a particular jurisdiction’s aquatic environment for which no standard has been developed or implemented.

Different jurisdictions will, however, have different priorities with respect to the substances which are taken forward for standard development, and therefore, a jurisdiction with no standard for a particular substance may be able to fill such gaps by utilising the output of a process from another jurisdiction. This may range from simply utilising the reliability and relevancy assessed ecotoxicity dataset compiled by another jurisdiction, to adaption or direct adoption of the alternative standard.

wca has been involved in a number of projects over the last few years which seek to assess the applicability, reliability and relevance of water quality standards derived by one jurisdiction for use in another. In some cases, this process is focussed on the comparison of datasets, for example, temperate versus tropical species, while in others we have developed frameworks for the detailed evaluation of water quality standards developed by one jurisdiction for use in another. In general, such frameworks cover:

  • Procedures for the assessment and selection of the most suitable alternative standard for use within a particular jurisdiction,
  • An assessment and expression of the applicability of an alternative guideline to a jurisdiction, based on the data and approaches used to derive it,
  • The likely status of alternative standards compared to those developed within a jurisdiction, and the resultant degree of flexibility that can be employed with regard to compliance with the procedures used with a jurisdiction for standard development,
  • The potential for adaptation of alternative standards for use within a jurisdiction.

These frameworks are designed to be adaptable and therefore can be tailored to the specific requirements of any jurisdiction’s or country’s procedures and approaches to chemical standard development.