Cal. Gov. Code § 31835.02
Notwithstanding any other provision of this part, Section 31835 shall also apply to any member who was a member of a retirement system established under this chapter and who subsequently becomes a member of the Public Employees' Retirement System, a retirement system established under this chapter in another county, the State Teachers' Retirement System, or a retirement system of any other public agency of the state that has established reciprocity with the Public Employees' Retirement System subject to the conditions of Section 31840.2, providing the period intervening between the periods for which active service was credited does not exceed 90 days, or six months if Section 31840.2 applies, and the member retires concurrently under both systems and is credited with the periods of service at the time of retirement.
This section shall only be operative in any county of the fourth class as described in Sections 28020 and 28025 if it is adopted by a majority vote of the board of supervisors.
Ca. Gov. Code § 31835.02