(a) Except as provided in subdivision (b) of this section, a retirement allowance or optional death allowance, including an allowance payable to a survivor of a member, payable to or on account of any member of this system, or of a superseded system, who retired for service on or before December 31, 1971, is hereby increased as follows:
Number of Years of
Percentage of Increase in
County or District
Monthly Retirement
Service
Allowance
25 or more years
10%
20–25 years
8%
15–20 years
6%
10–15 years
4%
(b) No allowance shall be increased to more than five hundred dollars ($500) per month pursuant to subdivision (a) of this section.
This section shall not be operative in any county until such time as the board of supervisors shall, by resolution adopted by majority vote, make the provisions of this section applicable in such county.