LOS ANGELES— The Center for Biological Diversity and the Wishtoyo Chumash Foundation filed a formal notice today of their intent to sue the Bureau of Ocean Energy Management over the agency’s failure to require updated development plans for oil drilling at the troubled Santa Ynez Unit off the California coast.

The unit’s three platforms have been shut down since May 2015, when a corroded pipeline ruptured and released what is believed to be about 450,000 gallons of oil near Refugio State Beach. The oil spill killed hundreds of birds and marine mammals, including dolphins and sea lions.

Sable Offshore Corp., the pipeline’s new owner, wants to restart production at the Santa Ynez Unit relying primarily on outdated development plans written in the 1970s and 1980s. BOEM has not required Sable to revise or supplement the plans.

“I’m horrified that these zombie oil platforms may be allowed to restart after a decade of dormancy,” said Kristen Monsell, oceans legal director at the Center for Biological Diversity. “Offshore drilling is always dangerous but relying on woefully outdated plans raises the safety and environmental risks. If the agency tasked with managing ocean drilling isn’t even asking for a plan from this century before letting companies extract oil, our coastlines are really in trouble. It’s so frustrating that we have to sue the regulator to get them to do their job.”

Today’s notice says BOEM would be violating the Outer Continental Shelf Lands Act if it allows drilling at the Santa Ynez Unit to proceed in federal waters without requiring updated plans. The agency is ignoring numerous harms from offshore oil and gas activity, including air pollution, risk of oil spills and contributing to climate change.

“The Santa Ynez Unit has continued to be a looming threat to Chumash cultural resources, marine ecosystems and the communities of Santa Barbara County,” said Mati Waiya, executive director of the Wishtoyo Chumash Foundation. “BOEM has betrayed the public’s trust by rubber stamping the restart of this air quality and public safety nightmare.”

The letter notifies BOEM that the Center will file suit unless the agency requires Sable to provide updated development plans before obtaining approval for restarting offshore drilling at the Santa Ynez Unit.