Regulators and Southern California Gas Co. (SoCalGas) have reached a $71 million settlement over the 2015 Aliso Canyon natural gas leak, the largest in U.S. history.

The California Public Utilities Commission (CPUC) said late Thursday the agreement requires Sempra Energy’s SoCalGas to pay the penalty into the Aliso Canyon Recovery Account. The California Legislature created the account to address public health fallout from the leak, which started in October 2015 and lasted until February 2016. Nearly 100,000 tons of methane were released into the atmosphere during that span.

The agreement further prevents SoCalGas from recovering the settlement’s costs from ratepayers. The utility also cannot bill customers for various other costs related to the leak, including $1.8 billion...