RODEO (KPIX) — The Bay Area is one of the biggest oil refining hubs on the West Coast. Tanker traffic is always heavy and it’s on target to get heavier and potentially riskier.

When it comes to big oil, California politicians hope you won’t pay attention to what’s criss-crossing the San Francisco Bay.

Oil tankers may one day be carrying the heaviest, dirtiest oil on the planet: tar sands crude from Alberta, Canada.

crude oil Oil Tankers May Carry Harmful Tar Sands Through Bay Area Waters

Tar sands crude (Suncor Energy)

“That oil could end up sinking to the bottom of the bay,” said Sejal Chokski-Chugh, executive director of Baykeeper, a nonprofit watchdog group that monitors pollution in the bay.

Read more on CBS San Francisco.