Cal. Pub. Res. Code § 3251

For the purposes of this article, an oil or gas well is a “hazardous well” if the supervisor determines that the well is a potential danger to life, health, or natural resources and there is no operator determined by the supervisor to be responsible for plugging and abandoning the well under subdivision (c) of Section 3237. Also, for the purposes of this article, an oil or gas well is an “idle-deserted well” if the supervisor determines that the well is deserted under Section 3237 and there is no operator responsible for its plugging and abandonment under Section 3237.