ComPArison of thE ProPosEd ECosystEm ProtECtion GuidElinE vAluEs for diuron in frEsh And mArinE ECosystEms With ExistinG triGGEr And ProtECtivE ConCEntrAtion vAluEs

Currently, there are eight different sets of protective concentration values, trigger values and guideline values for ecosystem protection for diuron in Australian waters. Included among these are the guideline values that we are proposing for diuron in freshwaters and marine waters that were generated as part of the revision of the Australian and New Zealand Guidelines for Fresh and Marine Water Quality. These proposed guideline values will be submitted for national endorsement and incorporation into the Guidelines and the Great Barrier Reef Water Quality Guidelines. The various sets of guideline values differ substantially from each other. This paper was prepared with three primary aims: 1) to examine the various sets of protective concentration values, current trigger values, and the proposed guideline values for freshwater and for marine waters; 2) to explain how the different values were derived; and 3) to explain the purpose of each set of values. This study provides a comprehensive evaluation of the various sets of ecosystem protection values for diuron, and presents arguments for why the proposed guideline values should be adopted and used in preference to existing trigger values or protective concentration values derived prior to 2017.