Potential Effects of Contaminants on Fraser River Sockeye Salmon

quality index scores were also calculated for each habitat sockeye salmon stockcombination. Such water quality index scores were plotted over time for the entirewatershed to determine if temporal trends in water quality conditions were evident. Theresults <strong>of</strong> this evaluation showed that water quality conditions in spawning and incubationhabitats did not exhibit any significant trend (Figure 5.1). However, the ranges <strong>of</strong> thewater quality index scores for the pre-1990 and post-1990 (and particularly post-1992)periods suggest that water quality conditions may have become less variable and poorerover the last 15 - 20 years. No such trends are evident for the rearing areas over theperiod <strong>of</strong> record (i.e., 1970 to 2009). For the migration corridors, water qualityconditions generally showed a downward trend for the period 1965 to 1990, are consistentbetween 1990 and 2003, and show improvement thereafter (Figure 5.1). However, theselatter results (i.e., for the post-2003 period) should be interpreted cautiously because suchchanges in water quality conditions coincided with the time that municipalities assumedresponsibility for ambient environmental quality monitoring. The results <strong>of</strong> suchmonitoring activities are typically not included in the EMS database that was accessed tocompile the data used to support this evaluation. Hence, it is uncertain if the observedimprovements in water quality conditions after 2003 reflect actual conditions in themigration routes <strong>of</strong> sockeye salmon.5.4 Evaluation <strong>of</strong> the <strong>Potential</strong> <strong>Effects</strong> <strong>of</strong> <strong>Contaminants</strong> <strong>of</strong> Concern on SockeyeSalmonAdverse effects on sockeye salmon utilizing habitats in the Fraser River Basin associatedwith exposure to contaminants <strong>of</strong> concern were evaluated by integrating exposure andeffects data and information. More specifically, hazard quotients were calculated for eachcontaminant <strong>of</strong> concern in surface water for each <strong>of</strong> the following habitats in each area <strong>of</strong>interest:• Spawning and incubation habitats;• Rearing habitats;• Smolt outmigration habitats, and,• Adult upstream-migration habitats.In this evaluation, hazard quotients (HQs) were calculated by dividing the exposure pointconcentration (EPC) by the selected toxicity threshold (TT) (i.e., HQ = EPC ÷ TT). Forsediments and fish tissues, hazard quotients were calculated for each contaminant <strong>of</strong>63