Domestic sewage is a major threat to receiving waters throughout the world. In Canada, a high proportion of the population (81%) is served by municipal wastewater treatment facilities. Nevertheless, discharges from wastewater treatment plants, stormwater sewers and combined sewers have caused adverse impacts on some lakes, rivers and coastal waters. The most publicly recognized impacts are shellfish harvesting restrictions and beach closures resulting from microbial contamination. Habitat degradation and contamination also occur and these, in turn, have altered the abundance and diversity of aquatic organisms. Our findings on the effects of municipal wastewater discharge suggest that there is a need to review sewage treatment requirements in Canada. Further research is also required on the interactive and cumulative responses to habitat degradation and to long-term exposure to persistent and bioaccumula-tive pollutants. Finally, an integrated approach to wastewater management is needed that addresses loadings from treatment plants, stormwater sewers, combined sewer overflows and other wastewater sources.

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National water quality guidelines for protection of aquatic life were developed to address concerns regarding toxicity of antisapstains entering surface waters. A review of environmental chem-( ) istry, fate, and toxicology of didecyl dimethyl ammonium chloride DDAC was conducted. DDAC is used in Canada in antisapstain formulations for treatment of freshly sawn lumber, in disinfectant formulations, and as a molluscicide. DDAC is an active ingredient in the most widely used antisapstain formulation ( ) Kop-Coat NP-1 , and one of the most widely used pesticides in British Columbia; 454,400 kg of DDAC were used by lumber mills for antisapstain purposes in 1996. DDAC, a cationic surfactant, is highly water soluble, and binds rapidly to suspended solids and sediments. It is not persistent in the water column; movement to solid phase and microbial degradation are expected to be main routes of dissipation.( ) y1DDAC was reported to affect rainbow trout Oncorhynchus mykiss at levels as low as 0.1 mg L , and Daphnia magna at levels as low as 0.03 mg L y1 . It is not expected to bioaccumulate. An interim water quality guideline of 1.5 g L y1 derived according to the Canadian Council of Ministers of the ( ) Environment's CCME protocol for the derivation of water quality guidelines for protection of aquatic life is recommended. ᮊ

National water quality guidelines for protection of aquatic life were developed to address concerns regarding toxicity of antisapstains entering surface waters. A review of environmental chem-( ) istry, fate, and toxicology of didecyl dimethyl ammonium chloride DDAC was conducted. DDAC is used in Canada in antisapstain formulations for treatment of freshly sawn lumber, in disinfectant formulations, and as a molluscicide. DDAC is an active ingredient in the most widely used antisapstain formulation ( ) Kop-Coat NP-1 , and one of the most widely used pesticides in British Columbia; 454,400 kg of DDAC were used by lumber mills for antisapstain purposes in 1996. DDAC, a cationic surfactant, is highly water soluble, and binds rapidly to suspended solids and sediments. It is not persistent in the water column; movement to solid phase and microbial degradation are expected to be main routes of dissipation.( ) y1DDAC was reported to affect rainbow trout Oncorhynchus mykiss at levels as low as 0.1 mg L , and Daphnia magna at levels as low as 0.03 mg L y1 . It is not expected to bioaccumulate. An interim water quality guideline of 1.5 g L y1 derived according to the Canadian Council of Ministers of the ( ) Environment's CCME protocol for the derivation of water quality guidelines for protection of aquatic life is recommended. ᮊ

Canadian water quality guidelines CWQG for 3-iodo-2-propynyl butyl carbamate IPBC were developed based on a review of environmental chemistry, fate, and toxicology of IPBC. IPBC is used in Canada in antisapstain formulations for treatment of freshly sawn lumber, as an industrial mildewcide, and as an antimicrobial. In British Columbia, IPBC is an active ingredient in the most widely ( ) used antisapstain formulation Kop-Coat NP-1 ; 36,020 kg of IPBC were used by lumber mills for antisapstain purposes in 1996. IPBC is moderately soluble in water, and is not likely to adsorb to suspended solids or sediments. It is not persistent in the water column; hydrolysis is expected to be the main route of dissipation. IPBC was reported to affect fathead minnows at levels as low as 0.019 mg L y1