Imperial Metal's Red Chris gold and copper mine in northern B.C. will turn a trout lake into a holding pond for mine waste. (Imperial Metals)

The Supreme Court of Canada unanimously ruled Thursday that a British Columbia mining development can go ahead, even though the court said the project didn't go through all the required environmental assessments.

The Supreme Court sided with the appellant, MiningWatch Canada, which had argued that the Red Chris mine project did not go through a full federal environmental study.

However, the top court also said that because MiningWatch does not have a financial stake in the mine, the project would be permitted to proceed.

In the court's decision, Justice Marshall Rothstein wrote there was no justification to require the mine's owners to repeat the environmental assessment process when MiningWatch had not actually challenged those findings.

'The government can no longer shirk the environmental protection duties that Parliament has assigned to it,'— Lawyer Lara Tessaro, Ecojustice Canada

The Supreme Court noted that MiningWatch brought the issue forward as a test case of the federal government's obligations under the Canadian Environmental Assessment Act.

The decision is expected to mean that future large development projects will need to go through full environmental reviews.

The case centred on the Red Chris gold and copper mine in northern British Columbia, about 80 kilometres south of Dease Lake. The mine would turn a trout lake into a holding pond for mine waste, and excavate mountains of earth at the rate of 30,000 tonnes a day for decades into the future.

Following an environmental assessment of the project, the B.C. government approved it. The federal government decided it didn't need to conduct a full assessment, opting instead for a screening process. The federal government did not conduct public consultations, choosing to rely on responses to the B.C. assessment.

A coalition of environmental groups sued, saying the federal government had ignored its responsibilities.

Mixed reaction to decision

The Supreme Court's ruling was applauded by environmental groups.

"The Supreme Court has given Canadians back their voice and, with it, their ability to influence major industrial development across the country," said Lara Tessaro, a lawyer with Ecojustice Canada, who represented MiningWatch.

"This landmark decision confirms that the government can no longer shirk the environmental protection duties that Parliament has assigned to it," Tessaro said.

'This could add a huge economic, time, resource burden to work the federal government is already doing.'— Byng Giraud, Association for Mineral Exploration British Columbia

"The court has confirmed that the federal government cannot lawfully split proposed projects into little pieces and assess only pieces of them," she said.

But Byng Giraud, the vice-president of corporate affairs with the Association for Mineral Exploration British Columbia, said the decision raises concerns about the federal government's capability to conduct timely reviews.

"This could add a huge economic, time, resource burden to work the federal government is already doing," Giraud said.

"By removing that ability for them to judge, we've created a problem of resourcing. Frankly, environmental assessment in the North is a very long, long process as it is," he said.

Giraud maintained the federal government should be allowed to delegate to other agencies like the B.C. Environmental Assessment Branch, and noted the laws can still be changed.

"The federal government is required to review the federal Environmental Assessment Act, it has to be reviewed every five years, which is coming up this year, so this is timely," he said.