Cal. Health and Safety Code § 41753

(a) (1) It is the intent of the Legislature that the registration of, and the regulation of emissions from, portable equipment that is operated in more than one district and that is subject to the registration program be done on a uniform, statewide basis by the state board and that the permitting, registration, and regulation of portable equipment by the districts be preempted. (2) Notwithstanding paragraph (1), if the owner or operator of portable equipment elects not to register under the statewide registration program, the unregistered portable equipment shall be subject to district permitting requirements pursuant to district regulations. (b) On and after the effective date of the statewide registration program established by the state board pursuant to subdivision (a) of Section 41752 and upon the registration of portable equipment by the portable equipment owner or operator, a district shall not, with respect to the affected portable equipment, do any of the following: (1) Require a permit for the construction or operation of the portable equipment. (2) Assess any fee related to the construction or operation of the portable equipment, other than that specified in paragraph (2) of subdivision (d) of Section 41752. (3) Adopt any emission limit or emission control requirement applicable to the portable equipment. (4) Except as provided in Section 41755, enforce any emission limit or emission control requirement applicable to the portable equipment. (c) The state board, in consultation with affected districts, shall amend the state implementation plan as necessary to include the statewide registration program and conform the state implementation plan to its requirements.