The chief eco-watchdog of the United States has set out to jump north across the border and bark in Canada.

The U.S. Environmental Protection Agency (EPA) filed Thursday to become a participant in the review of Kinder Morgan Canada’s proposed expansion of the Trans Mountain Pipeline across Alberta and British Columbia, from Edmonton to Vancouver.

The project is a contested Canadian counterpart to TransCanada Corp.’s fiercely resisted Keystone XL proposal for an oilsands export express line from Alberta to the Texas coast of the Gulf of Mexico.

For C$5.4 billion (US$4.9 billion), Kinder Morgan aims to load tankers at expanded Vancouver docks with Alberta bitumen by nearly tripling capacity on 1,150-kilometer Trans Mountain to 890,000 b/d from 300,000 b/d.

In a filing with the National Energy Board (NEB), EPA’s Region 10 office in Seattle — the agency’s Washington, Oregon, Idaho and Alaska jurisdiction — lodged a formal motion seeking the right to participate as an expert commenter on Trans Mountain.

The EPA’s role in Canada would focus on environmental and socio-economic effects of the pipeline project and be performed by R. David Allnutt, director of Region 10’s office of ecosystems, tribal, and public affairs, the filing says. The U.S. agency intends to focus on five issues:

The EPA filing observes that the Trans Mountain project plus a dock planned on the Washington coast at Cherry Point — the proposed Gateway Pacific Terminal — spell an additional 865 tanker voyages per year in the Strait of Juan de Fuca between the United States and Canada.

Although Trans Mountain does not cross the border, the EPA predicts that, “nearly tripling the capacity of the current pipeline will have potential air quality impacts on the trans-boundary air shed, including the U.S. portion.”

EPA region 10 also has special “responsibilities for environmental protection within Indian country and of tribal resources that are outside of Indian country including treaty-protected hunting and fishing areas and subsistence areas under state and federal jurisdiction,” says the agency’s filing with the NEB.

Last month the Canadian board turned down an EPA request to enter the Trans Mountain case after the deadline for registration of interveners and expert commenters passed on Feb. 11. EPA Region 10 blamed its tardiness on late discovery of the Trans Mountain proceeding, then further delay due to “internal coordination and approval requirements including coordination with EPA Headquarters in Washington, DC, and the U.S. State Department.”

EPA Region 10’s request for late recognition drew no immediate response from the NEB or participants in the Trans Mountain case. But the formal motion for commenter status opens a door to a debate involving all concerned, depending on how Kinder Morgan, other interests and their lawyers react.

Apart from issues of procedure and particulars of the Trans Mountain project, the agency’s request raises larger questions in Canadian government and industry circles that have become highly sensitive to U.S. behavior as a result of the Keystone XL case. Is this a projection of American power beyond the U.S. border on behalf of environmental interest groups? Or is the EPA inaugurating a pathway towards international regulatory co-ordination with potential to improve clarity and save time on major project reviews?