Potential Effects of Contaminants on Fraser River Sockeye Salmon

concern, for each area <strong>of</strong> interest, for each life-history stage, and for both the pre-1990and post-1990 time periods (Tables 4.32 to 4.44). The maximum hazard quotient for theentire period <strong>of</strong> record (i.e., the maximum hazard quotient <strong>of</strong> the pre-1990 and the post-1990) was used to identify chemicals <strong>of</strong> potential concern that have potential to adverselyaffect sockeye salmon during individual key life-history stage exposure periods (e.g.,juvenile rearing; Tables 4.45 to 4.48).The results <strong>of</strong> this assessment indicated that 23 chemicals <strong>of</strong> potential concern have beenmeasured in surface water at concentrations sufficient to pose potential risks to sockeyesalmon eggs, alevins, fry, smolts, or adults (Table 4.49), including:• Conventional variables (pH, TSS, and turbidity);• Nutrients (nitrate, nitrite, and phosphorus);• Major ions (chloride, fluoride, and sulphate);• Metals (aluminum, arsenic, boron, cadmium, chromium, cobalt copper, ironlead, mercury, nickel, selenium, and silver); and,• PhenolsAlthough the maximum hazard quotients for cadmium, chromium, and mercury werealmost certainly influenced by sample contamination issues, there were numerous resultsthat showed exceedances <strong>of</strong> the toxicity screening values for these metals that were notcontaminated during sample collection, handling or transport. Therefore, all <strong>of</strong> thesesubstances were identified as contaminants <strong>of</strong> concern (Table 4.49).In the Fraser River Basin, both spawning and incubation habitats and adult upstreammigration habitats had a higher percentage <strong>of</strong> measured chemicals <strong>of</strong> potential concernexceeding toxicity screening values during post-1990 period, compared to the pre-1990period (Table 4.50). In spawning and incubation habitats, 69% (20 <strong>of</strong> 29) chemicals <strong>of</strong>potential concern had at least one or more exceedances <strong>of</strong> a toxicity screening value in oneor more areas <strong>of</strong> interest post-1990. For the pre-1990, 62% (17 <strong>of</strong> 27) <strong>of</strong> measuredchemicals <strong>of</strong> potential concern had one or more measurements exceeding a toxicityscreening value (Table 4.50). Similarly, adult upstream migration habitats hadexceedances <strong>of</strong> the toxicity screening values for 66% <strong>of</strong> measured chemicals <strong>of</strong> potentialconcern (23 <strong>of</strong> 35) in the post-1990 period compared to 60% (18 <strong>of</strong> 30) for the pre-1990period. These results suggest that water quality conditions have degraded over the pasttwo decades. However, the results were reversed for the juvenile rearing and smoltoutmigration life stages.53