Proposed aquatic ecosystem protection guideline values for pesticides commonly used in the Great Barrier Reef catchment area: Part 2 – Bromacil, Chlorothalonil, Fipronil, Fluometuron, Fluroxypyr, Haloxyfop, MCPA, Pendimethalin, Prometryn, Propazine, Propiconazole, Terbutryn, Triclopyr and Terbuthylazine

Executive summary
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 second 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 13 pesticides presented in Part 1 (King et al. 2017) 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 (this report) 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.
The 14 pesticides presented in Part 2 (this report), constitute a suite of chemicals for which there are comparatively few toxicity data. As a consequence, several of the Proposed Guideline Values presented in this report are categorised as being of low reliability (Warne et al. 2015). It is anticipated that some of the Proposed Guideline Values presented here will change when more toxicity data become available. Hence, the adoption of the Proposed Guideline Values as part of a risk assessment process needs to take into consideration the reliability rating and the pending availability of new data.