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.

Environmental effects monitoring (EEM) is a requirement for pulp and paper mills in Canada discharging effluent directly into receiving environments under the Pulp and Paper Effluent Regulations of the Fisheries Act. The objective of the EEM program is to assess effects on fish, fish habitat and the use of fisheries resources by humans, potentially affected by the deposit of mill effluent in aquatic receiving environments. The information provided by the monitoring program will contribute to assessing the adequacy of the regulations. Difficulties encountered in the first round of monitoring led to an extensive science review of key components and resulted in improvement to process, scientific defensibility of the monitoring data and site-specific flexibility of the EEM program. The second cycle of EEM was, overall, markedly more successful than Cycle 1. However, problems were still evident for fish surveys conducted in marine and estuarine environments. The adoption of improved alternative monitoring approaches (e.g., caged bivalves, mesocosms) should alleviate many of these problems. An overview of the EEM program, results to date, alternative monitoring approaches, and research priorities to fill data gaps are presented.

A comparison of declining forests in Alaska, British columbia, and the Pacific Northwest United States to forest declines in eastern North America indicated that strong similarities existed and justified the use of the western forest region as an 'acid rain' control. The current level of wet acidic deposition over the western region was one-quarter that of eastern Canada and the United States. The onset of crown dieback on Chamaecyparis nootkatensis (1900) and Pinus monticola (1936) did not relate to the incidence of regional air pollution but to extreme climatic variation. The injury mechanism differentiating persistent decline on Pinus monticola from sporadic but transient dieback, which was observed on a larger number of conifer and deciduous tree species, was believed to be cavitation. This dysfunction of the xylem was induced by anomalous winter thaw-freeze conditions in 1936 followed by high summer temperatures and evapotranspiration stress in that and subsequent years. Similar extreme climatic conditions were present at the onset of forest declines in eastern North America and central Europe which suggests that the climate-cavitation-forest decline mechanism may be universal.

Data from the sublethal toxicity testing of effluents may or may not be predictive of field effects. Although qualitative studies have attempted to support a predictive relationship at select sites, few quantitative studies have been undertaken to establish whether general predictive relationships exist for diverse recipient environments. Since Canada's Environmental Effects Monitoring (EEM) Program encompasses a strong field component as well as a suite of sublethal toxicity tests, the Cycle 2 data set of the Pulp and Paper EEM Program presented an opportunity to elucidate whether relationships exist between various sublethal toxicity endpoints used in EEM and field effects that were determined in surveys of benthic invertebrate communities and fish populations. Sublethal toxicity data and key endpoints from the fish (gonad weight, liver weight and condition) and invertebrate surveys (taxon richness and abundance) were quantitatively analyzed using simple bivariate correlation analysis. Our preliminary analysis of the data did not reveal any meaningful general relationships between the field biomonitoring and sublethal toxicity data collected under the Pulp and Paper EEM Program. Although the sublethal toxicity tests are useful to assess changes in effluent quality, their ability to predict the field effects for the key endpoints that are currently measured for fish and benthos in the Pulp and Paper EEM Program remains unsubstantiated.

Abstract-The Canadian water quality guidelines for the protection of aquatic life assume that (1) the external water concentration is an effective measure of the concentration at the active site in organisms, which is ultimately responsible for a toxic response, and that (2) the safety factor accounts for any differences between laboratory and field conditions as well as the extrapolation from the effect concentration to a long-term no-effect concentration. This study examines these assumptions and assesses potential errors that environmental managers can make when applying the guidelines. The methodology is based on assessing the probability that internal concentrations of several contaminants are greater than or less than the ''safe'' concentration, assumed by the guideline, when the water concentration is at the water quality guideline. Results derived from empirical observations and a food-web bioaccumulation model show that a high probability (62-100%) exists that safe internal concentrations are exceeded for polychlorinated biphenyls, 1,2,4,5-tetrachlorobenzene, and hexachlorobenzene in Lake Ontario when the aqueous concentrations are at the water quality guideline values. This is due to field bioaccumulation factors being greater than the bioaccumulation factors in laboratory toxicity tests used for the water quality guideline development. Factors contributing to the exceedence of safe internal concentrations at the water quality guideline values are identified. Recommendations for improvement of the water quality guideline process are provided.