LOS ANGELES (AP) — An investigation into the cause of the largest-known release of methane in the U.S. faults a California utility for the way it maintained its natural gas storage field before the massive 2015 blowout.

The report released Friday by the California Public Utilities Commission says Southern California Gas Co. didn't assess its wells for disaster potential and didn't investigate previous ruptures.

The report by Blade Energy Partners says the blowout that lasted nearly four months and was blamed for sickening thousands of Los Angeles residents could have been plugged sooner.

The u...