The province has denied an environmental certificate for a proposed copper mine in north central B.C., a rare refusal that signals optimism for Ajax opponents in Kamloops.

The decision to reject approval for Morrison Mine was made by Environment Minister Terry Lake and Ministry of Energy, Mines and Natural Gas Rich Coleman.

Lake said Monday that rejection of the certificate based on a recommendation from the director of B.C.'s environmental assessment office.

The proposed copper-gold-molybdenum project is located about 35 kilometres north of the village of Granisle, near Babine Lake.

The Morrison project is located near two other historic properties: Bell Mine and Granisle Copper Mine. Those mines are located immediately beside Babine Lake, the province's longest natural freshwater lake.

Lake Babine First Nation said the lake is home to genetically distinct sockeye but numbers are depressed from over-harvesting and leachate contamination from the closed mines.

"We can't risk trading a renewable, sustainable fishery for a non-renewable mine that will leave a legacy of contaminants and toxins in our territory," said chief Wilf Adam.

Officials with project promoter Pacific Booker Minerals declined comment Monday.

The proposed mine, beside 15-kilometre-long Morrison Lake, was estimated to produce 30,000 tonnes of ore a day for a 21-year mine life. That compares to 60,000 tonnes and 24 years for the proposed Ajax Mine immediately south of Kamloops.

Critics of B.C.'s environmental laws say the province almost never turns down mine projects. The most glaring example was the proposed Prosperity Mine in the Chilcotin, conditionally approved by the B.C. government to receive an environmental certificate but turned down by Ottawa.

"I hear our critics talking about how our environmental process approves everything and that's simply not true," Premier Christy Clark told the Canadian Press.

Lake said Monday the threat to salmon stocks in Morrison Lake posed too great a risk. The lake is located at the headwaters of the Skeena River system.

"One of the biggest (factors) is lack of information about behavior of Morrison Lake, where some effluent would go."

The project called for a rubber membrane to line a tailings pond, measuring about five square kilometres.

"That's never been done in B.C. There were too many things that raised questions."

Judith Naylor, president of Kamloops Area Protection Association, said the decision should give hope to residents here opposed to Ajax mine and its location within two kilometres of existing South Kamloops neighbourhoods.

She said the B.C. Liberal government "could be getting the message" about the importance of the environment and communities.

"I don't think it's as gloomy and done as people are painting," she said. "Do we want our land sacrificed? I'm not sure all is lost. There's a fighting chance."

Concern about salmon proved the insurmountable hurdle at Morrison. Lake said Ajax's location beside a city of 85,000 is one of its major challenges .

"It's very much a project-by-project approach. It's not one-size-fits-all."

NDP critic Doug Donaldson said fisheries and First Nations issues dogged the project

"With any mine you have to let the environmental assessment process unfold. Right now we believe there are defects in the process."

The B.C. Liberal government announced Sunday it has made changes to the environmental assessment system in response to an auditor-general's report. That report found serious flaws in lack of inspections and enforcement once mines are given certificates and operation started.

Lake said there will be more monitoring along with enforcement and public reporting of inspections. But Donaldson countered that only "66 per cent" of the auditor-general's recommendations have been put in place.

"We want an environmental process the public has trust in and gives investors confidence."