Serpent River Watershed Study

More than 7,000 lakes around Sudbury, Ontario were acidified by acid precipitation caused by more than a century of sulphur emissions from Sudbury smelting operations. Emission reduction requirements were implemented for those smelters in the 1970s and 1990s and achieved a 90% reduction in sulphur emissions. These acid lakes have responded to the reductions with measurable chemical and biological recovery. Many lakes in the Serpent River watershed to the west of Sudbury were acidified and otherwise contaminated as result of tailings dam failures at uranium mining operations in the Elliot Lake area in Ontario, and suffered severe chemical and biological impairment. Tailings control measures were implemented in the area in the 1980s and the lakes have since been recovering.

In this study, we are comparing recovery of lakes in these two areas. Work began in 2011 with the assembly of historical water chemistry data for both, zooplankton and water chemistry sampling in one Serpent River Watershed Lake and a Daphnia pulicaria bioassay of water from that lake. Preliminary results suggest that Serpent River Watershed lakes have recovered more quickly than those in the Sudbury region, however further work is needed, and over the next four years will include additional zooplankton sampling, comparative bioassays, sediment core analyses, landscape evaluations and microbial community activity comparisons.