The guidelines apply to the ambient raw water source before it is diverted or treated for domestic use. The Ministry of Health regulates the quality of water for domestic use after it is treated and delivered by a water purveyor. Guidelines relating to public health at bathing beaches are the same as those used by the Ministry of Health which regulates the recreation and aesthetic use. Theoretically, a large number of compounds can belong in the PAH category. The environmentally significant PAHs, however, are those molecules containing two to seven benzene rings.
Several factors determine the physical, chemical and biological characteristics of PAHs.
Forest fires and prairie fires, agricultural burning, and fossil-fuels are the major contributors of PAHs to the environment. The following criteria are based on information presented in the main body of the report, and are summarized in Table 2 . and Table 3 . The criteria in Table 1 are interim criteria. They will be superseded by criteria from Canadian or British Columbia health authorities. Wildlife PAH criteria for wildlife are not recommended in this document due to the lack of pertinent information in the literature.