California Code, Health and Safety Code - HSC § 25159.24

(a) Any injection well used to inject contaminated groundwater that has been treated and is being reinjected into the same formation from which it was drawn for the purpose of improving the quality of the groundwater in the formation is exempt from this article if this method is part of a remedial program initiated in response to an order, requirement, or other action of a federal or state agency.

(b) Any injection well used for the reinjection of geothermal resources, as defined in Section 6903 of the Public Resources Code, is exempt from this article if the well is in compliance with Chapter 4 (commencing with Section 3700) of Division 3 of the Public Resources Code.