Proposed aquatic ecosystem protection guideline values for pesticides commonly used in the Great Barrier Reef catchment area: Part 1 – 2,4-D, Ametryn, Diuron, Glyphosate, Hexazinone, Imazapic, Imidacloprid, Isoxaflutole, Metolachlor, Metribuzin, Metsulfuron-methyl, Simazine and Tebuthiuron.

The Australian and New Zealand Guideline for Fresh and Marine Water Quality, also referred to as the National Water Quality Guidelines (ANZECC and ARMCANZ 2000), provides toxicity-based default guideline values (formerly referred to as a trigger values) for numerous inorganic and organic chemicals of environmental concern, including guideline values for fifty individual pesticides. This number falls well short of the total number of pesticides used in Australia and under-represents many of the pesticides currently used in Great Barrier Reef catchments. The National Water Quality Guidelines are currently being revised as part of the National Water Quality Management Strategy (NWQMS).
Under several different funding arrangements, the Queensland Government Department of Science, Information Technology and Innovation (DSITI) have been engaged in the derivation of new or revised aquatic ecosystem protection guideline values for 27 pesticides commonly detected in the Great Barrier Reef catchments. All aquatic ecosystem protection guideline values have been derived using the revised method for deriving water quality guidelines for toxicants (Warne et al. 2015). In Australia, water quality guideline values are preferably derived using a species sensitivity distribution (SSD) approach. The intent is that all these aquatic ecosystem protection guideline values are ultimately endorsed as National default guideline values. Until such time that they have received endorsement by the Standing Committee for the Revision of the National Guidelines, these derived guideline values will be termed as proposed aquatic ecosystem protection guideline values. In the interest of brevity, in this report they are also referred to as Proposed Guideline Values (PGV).
This report is the first part of a two-part series that presents the Proposed Guideline Values for 27 pesticides commonly detected in both, freshwater catchments and marine waters of the Great Barrier Reef. The Proposed Guideline Values have been split across the two separate reports depending on the funding arrangements under which they were derived. The Proposed Guideline Values for glyphosate, metolachlor, metsulfuron-methyl, and simazine were derived under contract with the Commonwealth Government Department of the Environment (DoE) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO), and were derived for inclusion in the revised Australian and New Zealand Guidelines for Fresh and Marine Water Quality. At the time of writing, publication of the revised Australian and New Zealand Guidelines for Fresh and Marine Water Quality was still pending. The Proposed Guideline Values for 2,4-D, imazapic, isoxaflutole and metribuzin were derived as part of a project funded by the National Environmental Research Programme (NERP). The Proposed Guideline Values for ametryn, diuron, hexazinone, imidacloprid and tebuthiuron were derived as part of a research project funded by the Queensland Department of Science, Information Technology and Innovation (DSITI).
The 13 pesticides presented in Part 1 (this report) were selected based on the priorities of Commonwealth and State government departments and stakeholders, and are currently being reviewed for endorsement as National guideline values. The 14 pesticides included in Part 2 (King et al. 2017) are also detected regularly in catchments discharging to the GBR lagoon (Wallace et al. 2016). Currently, there are either, no, or only low reliability National guideline values in existence for these pesticides. As part of a project funded by the Queensland Department of Environment and Heritage Protection, the Queensland Department of Science, Information Technology and Innovation has derived Proposed Guideline Values for fresh and marine ecosystems for these 14 pesticides.