PG&E, the state’s largest investor-owned utility, faces an estimated $30 billion exposure to liability for damages from the 2017 and 2018 wildfires that killed scores in Northern California. The sum would exceed its insurance and assets, raising concern in the state capital about the utility’s future.

The billions in potential costs have prompted a series of downgrades in PG&E’s ratings, including decisions last week by Moody’s Investors Service and S&P Global Ratings to downgrade the utility’s bonds to junk.

The “action is driven entirely by the further weakening of Pacific Gas and Electric Company’s credit quality,” Moody’s stated in its decision.

Gov. Gavin Newsom has said that responding to the utility and wildfire issues are among his top priorities after taking office last week.

Fire investigators determined that PG&E’s equipment was responsible for at least 18 of 21 major fires in 2017 as well as fires in 2018. Some of the fires have been attributed to power lines’ coming into contact with trees, which critics have said is a result of the utility’s failure to trim the trees.