The Ministry of Environment says copper, iron, manganese, arsenic, silver, selenium and vanadium were found in concentrations that exceeded provincial standards during testing near the Mount Polley mine Aug. 12 and Aug. 15.
The early August failure of the mine's tailings pond released millions of cubic metres of water and silt into local fish-bearing streams.
But the ministry says testing before the spill, at the end of May, also showed the seven chemical elements exceeded the same provincial guidelines.
Interior Health will continue to monitor testing results for potential long-term health risks, and the agency continues to advise local residents not to drink cloudy water.
Mine owner Imperial Metals is responsible for cleaning up the spill, and several investigations are examining the causes of the breach.