It is one in a series which establishes ambient water quality criteria for British Columbia. The criteria are safe conditions or levels of contaminants, applicable province-wide, which protect various water uses. No criteria are established for drinking water, wildlife, livestock watering, irrigation, recreation and aesthetics, or industrial water uses since TGP affects only aquatic life. The criteria are summarized in Table 1. and Table 2 . Excess TGP produces a class of physiological signs referred to as gas bubble trauma which are harmful or fatal to fish and other freshwater and marine organisms.
Fish are the most sensitive organisms in marine and freshwater environments.
TGP criteria for fish should protect all aquatic life. A major use of criteria is to set ambient water quality objectives. The objectives are the criteria modified or adopted to protect the most sensitive designated water use in a particular body of water. The objectives are used in the preparation of waste management permits, orders, or approvals, which are the only documents to have legal standing. The objectives, however, are not usually part of the permit.