The discharge of dye and salt tracer material, excluding radioisotope tracers, into water is a permitted activity subject to the following conditions:
The discharge of tracer material to water which does not comply with Rule 184.108.40.206 is a discretionary activity (requiring resource consent).
Explanation and Principal Reasons for Adopting Methods 220.127.116.11 and 18.104.22.168
Section 15 of the RMA restricts the discharge of contaminants into water unless the discharge is expressly allowed by a rule in a regional plan or by a resource consent. Dye and tracer materials that are non-toxic or inert generally do not have adverse environmental effects. In accordance with Policy 1, Rule 22.214.171.124 therefore allows the discharge of dye and salt tracers into water bodies provided certain conditions are met including ecotoxicity levels and the quantity of tracer used. The Rule encourages the use of non-toxic tracers instead of tracers that are toxic or carcinogenic.
With regard to Rule 126.96.36.199, there are several tracers that have the potential to cause adverse environmental effects. Radioisotopes, for example, are recognised as having an associated radioactive hazard. Other dyes or tracers which may have toxic or carcinogenic* effects include organic compounds such as pesticides, or microbial tracers e.g. some viruses. Dyes range in toxicological concern. It is illegal for example, to use Rhodamine B as a water tracer in the United States whereas Rhodamine WT is relatively safe. For these reasons Rule 188.8.131.52 provides for the discharge of all other tracer materials to water bodies to be assessed as discretionary activities.