It would mean very bad news, not just when there's a spill but from chronic oiling that happens as a matter of course when oil tankers habitually traverse a waterway like the Salish Sea.
CRED BC (http://credbc.ca/) has done some excellent work on the history of spills and leaks along the existing Trans Mountain Pipeline and on the economic risks and benefits of Kinder Morgan's proposal to expand the pipeline. The following two graphics are theirs.
And I wrote about the issue in a Bird Canada article last month. You can read it here.