A protocol for the derivation of water quality guidelines for the protection of aquatic life 2007 : Protocole d'élaboration des recommandations pour la qualité des eaux en vue de protéger la vie aquatique 2007

"The composition of aquatic assemblages and various physiological processes of aquatic plants and animals vary naturally with physical, chemical, geological, and hydrological conditions of the environment. Ecological attributes also fluctuate in response to elevated concentrations of natural and anthropogenic substances. Canadian Water Quality Guidelines for the Protection of Aquatic Life (CWQGs-PAL) are nationally approved limits of substances and other attributes (such as pH and temperature) in the water column where no adverse toxic effects are expected to aquatic plants and animals. The guidelines are one of a set of management tools developed to ensure that societal stresses, particularly the introduction of toxic substances, do not lead to the degradation of Canadian fresh and marine waters."