The federal department of Fisheries and Oceans has revoked a key permit for an Imperial Oil oilsands project north of Fort McMurray — a decision made mere weeks after a federal court judge ruled that the project’s environmental assessment didn’t adequately address the problem of greenhouse gas emissions.

On March 20, Imperial received a letter from the fisheries department saying the company “was not authorized to proceed with any activities that could potentially disrupt or alter fish habitat,” says Imperial Oil spokesperson Pius Rolheiser, adding it’s too early to tell if the revocation will “result in any material change to the project schedule.”

Environmentalists are cheering the permit’s revocation. “I think it’s the first time ever that either a federal government or [the] Alberta government has said ‘boo’ to a tar sands company,” says Sierra Club of Canada executive director Stephen Hazell. “It’s the first time they’ve ever said anything at all mildly critical…. Up until now, it’s been a free-for-all. [Companies] destroy as much as they want, they pollute as much as they want and basically governments look the other way.”

Imperial will challenge the revocation in federal court in early May. The company hopes the mine will start producing 100,000 barrels a day by 2011.

A joint federal-provincial government panel approved the Kearl project in 2007, but environmental law firm Ecojustice Canada launched a legal challenge to the approval on behalf of several environmental NGOs. The panel had said the project — which will produce emissions equivalent to those caused by 800,000 cars — wasn’t likely to “result in significant adverse environmental effects to air quality” because intensity-based targets were in place. The court, however, pointed out that the absolute amount of greenhouse gas emissions would still increase, and said the panel reached its conclusion “without any rationale as to why the intensity-based mitigation would be effective.”