This Regulation specifies the water quality criteria for protection of freshwater aquatic life and marine aquatic life and establishes standards with respect to the maximum permitted levels of ammonia–nitrogen in freshwater aquatic life. The Regulation prohibits the discharge into or use of water where any such discharge or use causes a deterioration of water quality below the prescribed water quality criteria, unless permitted under this Regulation. The terms and conditions of a permit may provide for a mixing zone where, after exploring all methods of waste avoidance and minimization, it is not viable or practicable to further reduce the level of waste prior to its discharge or emission. A “mixing zone” means a discrete body of water into which waste is discharged and for which the prescribed water quality criteria are not required to be met and the protection of aquatic life is not guaranteed.
Environment (Water Quality Criteria) Regulation 2002.