Buried within the more than 400 pages of this spring’s federal omnibus budget bill is an invitation for resource companies to open a new frontier in Canadian oil: the Gulf of St. Lawrence.

The gulf, which touches the coastlines of Canada’s five easternmost provinces, is the world’s largest estuary. It’s home to more than 2,000 species of marine wildlife — an ecosystem integral to the health of our Atlantic and Great Lakes fisheries.

Now, due to measures deep in the federal budget, that ecosystem may be under threat. The bill explicitly highlights the region’s potential for petroleum extraction and includes amendments to the Coasting Trade Act that give oil companies greater access to exploration vessels.

Corridor Resources Inc., a small Halifax-based company, is seeking to take advantage of the budget’s deregulation by applying to drill the first-ever deep-water well in the gulf. It’s just what the budget bill sought — and just what scientists and concerned citizens in the region have been fighting for years.

Green Party Leader Elizabeth May sounded the alarm last week, warning Canadians about the dangers of the project. A spill in the gulf would be a particular disaster, scientists who accompanied her said, because, due to the estuary’s counterclockwise tidal currents, it empties into the Atlantic only once per year. That means oil would almost certainly reach five coastlines, affecting land and livelihoods in all provinces touching on the gulf.

Even if no oil is spilled, the seismic method of exploration that Corridor proposes can be disfiguring or deadly for the gulf’s inhabitants. “Marine mammals and fish are highly impacted by seismic surveys,” said Lindy Weilgart, a biologist at Dalhousie University. “To carry out this destruction in as productive and biologically rich an area as the gulf is madness.”

Of course, there’s a debate to be had about how to negotiate between the economic benefits and environmental hazards of offshore oil. But for defenders of the gulf, it seems no debate is available.

The Newfoundland and Labrador Offshore Petroleum Board, which is responsible for evaluating Corridor’s proposal by July 2013, will have no way of measuring the nature or extent of the environmental risks. The budget rescinded the requirement for environmental assessments of exploratory drilling and crippled the Centre for Offshore Oil, Gas and Energy Research, the federal agency best equipped to deliver such assessments.

The federal government has picked oil and brushed aside concerns about the environment — and all this buried within the behemoth budget bill. If the government insists that we risk a rich and important ecosystem for the prospect of underwater oil, it should not be allowed to sneak that choice past us in a footnote.