A dam holding back the tailings pond at Imperial Metals' Mount Polley Mine in central B.C. burst open on Monday, releasing 10 million cubic metres of water and 4.5 million cubic metres of potentially toxic silt into adjacent lakes, rivers and creeks.
Government officials have acknowledged they still don't know what exactly leaked out, though tests on the water expected Thursday may provide at least some answers about the possible impact of the spill.
Federal environment and fisheries officials have so far deferred comment to the provincial government, which is leading the investigation and response, though Industry Minister James Moore became the first federal cabinet minister to weigh into the disaster during an unrelated event in Montreal.
"Those who are responsible for this should pay for this," said Moore.
"This should not be the responsibility of taxpayers."
The provincial Environment Ministry has ordered Imperial Metals Corp. (TSX:III) to immediately take action to prevent additional water and silt from leaking out of the tailings pond, account for what was in the tailings and provide a plan to clean it up. The ministry has said the company could face fines or even jail time if it fails to comply.
The province says Imperial Metals met a Wednesday deadline to provide a plan to stop continued pollution and for a preliminary environmental assessment and cleanup, though the documents have not been released publicly. Additional deadlines are set for next week.
Moore said mining is an important industry for B.C. and Canada, but he said resource companies must be run responsibly when it comes to protecting the environment.
"What happened here is certainly a terrible event," he said.
"It underlines the importance of having effective monitoring, effective regulation in place to protect our environment. ... It is certainly important that lessons be learned from this."
B.C.'s mines minister Bill Bennett has been the provincial government's lead spokesman on the Mount Polley file. Premier Christy Clark planned to visit the town of Likely, which is located near the mine site about 600 kilometres northeast of Vancouver, on Thursday.
The company has apologized for the spill, though it has also suggested the water and silt that escaped from the tailings pond is safe. Company president Brian Kynoch said the tailings pond water is almost drinkable, while he described the solids as "relatively benign."
Residents in the region have been under a water ban since Monday.
Preliminary results from government water testing are expected to be released Thursday afternoon, with more to follow in the coming days. The Environment Ministry says it has yet to take samples of the silt that spilled from the tailings pond due to safety concerns.
A summary of material dumped into the tailings pond filed last year with Environment Canada listed 326 tonnes of nickel, over 400,000 kilograms of arsenic, 177,000 kilograms of lead and 18,400 tonnes of copper and its compounds, though a significant amount of silt remains in the tailings pond.
On Monday, the same day as the breach, the company sent the provincial government data about the tailings pond water, which showed levels of selenium exceeded drinking-water guidelines and organic carbon concentrations exceeded guidelines for chlorinated water. Nitrate, cadmium, copper, iron and selenium have exceeded aquatic life guidelines at least sporadically in recent years.