Ontario and Quebec had set out seven principles for the $12-billion pipeline project, which would carry western crude to refineries in eastern Canada, the most notable relating to its potential impact on climate change.
But after meeting Prentice in her office, Wynne said her concerns were limited to greenhouse gas emissions from the pipeline project itself, not from the so-called upstream emissions resulting from getting the crude out of the ground, refining and burning it.
"On this project, we're talking about the reality that greenhouse gas emissions as they pertain to the project in Ontario, they need to be taken into account," she told reporters. "That's what the principle says."
Wynne insisted her stance was not a change in position, but she couldn't say exactly what potential greenhouse gas emissions would be generated by the pipeline project that have her concerned.
"That's for the discussion," she said. "We haven't outlined that."
TransCanada Corp. (TSX:TRP) has applied to use a repurposed natural gas pipeline to carry crude two-thirds of the way across the country, and to build a pipeline extension that would connect it to Saint John, N.B.
The National Energy Board will deal with all the principles raised by Ontario and Quebec as it reviews TransCanada's application, said Prentice.
"I have a better appreciation of where Premier Wynne is coming from in terms of the effects of that project in Ontario," he said. "The principles that have been put forward are logically the matters that the National Energy Board will be considering, and it doesn't surprise me that Ontario will be putting forward their perspective on those matters."
Ontario Environment Minister Glen Murray said all provinces need to work together on a national strategy to deal with climate change, adding it doesn't make sense to draw battle lines over every project like Energy East.
"What we're trying to do is get out of what has not been a very productive process, which is fighting over individual projects," said Murray. "Pull this back from a project-specific discussion to a larger strategy."
The group Environmental Defence said Wynne appeared "confused" about the climate impacts of the Energy East project when she said her concerns related only to greenhouse gas emissions in Ontario.
"This is bizarre, considering the vast majority of the climate pollution created by building Energy East would happen in Alberta," said spokesman Adam Scott. "Producing the additional oil needed to fill Energy East would increase Canada's net greenhouse gas pollution by 32 million tonnes, equivalent to putting seven million new cars on Canada's roads."
Ontario's opposition parties accused Wynne of failing to stand her ground when it comes to environmental concerns about the proposed pipeline.
"It's obvious that the premier is changing her tune today," said NDP Leader Andrea Horwath. "She needs to be clear with Ontarians, whether it's the upstream emissions or whether it's simply construction of the pipeline itself."
The Progressive Conservatives said Wynne should be concerned with the possible impact on natural gas prices from Energy East because it would repurpose a pipeline that currently delivers gas to Ontario.
"We don't want to see our natural gas prices go up just because we're extending the courtesy of allowing the pipeline to go across our property," said interim PC Leader Jim Wilson.
Prentice met Tuesday with Quebec Premier Philippe Couillard and Sunday with British Columbia Premier Christy Clark to talk about Energy East, which he calls a "nation building" project.
"It is a project that links together energy production in western Canada through to both the export and consumption of that from provinces in Atlantic Canada," said Prentice. "I believe that we can work together."
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