Results of routine sampling conducted on effluent (treated water) discharged into Lake Ontario from the portable water treatment system located on site at the Port Hope Harbour and Centre Pier on July 17 showed exceedances for copper and zinc above the action levels. Action levels are an internal threshold set well below the Canadian Nuclear Safety Commission’s regulatory weekly discharge limit. Results of other sampling parameters were in compliance with applicable requirements.
The water treatment system is currently being decommissioned. As a result, this was a batch discharge in limited volume. There have been no other discharges.
Results received within the usual two to three-week timeframe confirmed an exceedance for copper, Sample results for copper were in the range of 4.9 micrograms/litre, which is above the action level of 2-4 micrograms/litre. Results for zinc were 46 micrograms/litre, which is above the action level of 30 micrograms/litre.
As the effluent is diluted significantly at the discharge outfall into Lake Ontario, the risk to aquatic life and the environment from this event was negligible.