California Code, Public Resources Code - PRC § 42287

(c)(1) A city, county, or other local public agency that has adopted, before September 1, 2014, an ordinance, resolution, regulation, or rule relating to reusable grocery bags, single-use carryout bags, or recycled paper bags may continue to enforce and implement that ordinance, resolution, regulation, or rule that was in effect before that date.  Any amendments to that ordinance, resolution, regulation, or rule on or after January 1, 2015, shall be subject to subdivision (b), except the city, county, or other local public agency may adopt or amend an ordinance, resolution, regulation, or rule to increase the amount that a store shall charge with regard to a recycled paper bag, compostable bag, or reusable grocery bag to no less than the amount specified in Section 42283.

(2) A city, county, or other local public agency not covered by paragraph (1) that, before September 1, 2014, has passed a first reading of an ordinance or resolution expressing the intent to restrict single-use carryout bags and, before January 1, 2015, adopts an ordinance to restrict single-use carryout bags, may continue to enforce and implement the ordinance that was in effect before January 1, 2015.