Cal. Government Code § 31592.3

In any county, earnings of the retirement fund, in excess of the total interest credited to contributions and reserves shall remain in the fund as a reserve against deficiencies in interest earnings in other years, losses on investments, and other contingencies, except that when the total amount in the reserve exceeds 1 percent of the total assets of the retirement system, the board may transfer all or any part of such reserve in excess of 1 percent of the total assets into a special fund which shall be used for the sole purpose of providing an increase in monthly retirement allowance pursuant to Section 31681.7 or Section 31739.4. In the event the amount credited to the special fund is not sufficient to pay the entire amount of the increase provided for by Section 31681.7 or Section 31739.4 then the amount of the increase shall be reduced in proportion to the amount of the balance on hand in the special fund at the close of the fiscal year preceding the fiscal year during which such increase is operative. This section shall not be operative in any county until such time as the board of supervisors shall, by ordinance, make the provisions of this section applicable in such county. The board of supervisors may in such ordinance provide that the increase in monthly retirement allowance provided for by Section 31681.7 or 31739.4 shall be effective only subject to the provisions of this section.