Cal. PUC § 972

(a) A penalty assessed against a gas corporation pursuant to this part in regards to a natural gas storage facility leak shall at least equal the amount necessary to reduce the impact on the climate from greenhouse gases by an amount equivalent to the impact on the climate from the greenhouse gases emitted by the leak from the natural gas storage facility, as determined by the State Air Resources Board. In determining the amount necessary to fully offset the impact on the climate from the gases emitted by the leak, the commission shall consider the extent to which the gas corporation has mitigated, or is in the process of mitigating, the impact on the climate from greenhouse gas emissions resulting from the leak.

(b) This section shall not affect or be interpreted to affect the authority of the State Air Resources Board to adopt rules and regulations to reduce greenhouse gas emissions at natural gas storage facilities or to require mitigation of natural gas leaks from those facilities.