(a) In lieu of any other contingent expense allowance now provided by law for the Prosecuting Attorney of the Seventeenth Judicial District, the prosecuting attorney shall receive a contingent expense allowance of three thousand six hundred dollars ($3,600) per annum to be borne by the respective counties of the Seventeenth District as follows:
(1) White County $1,400;
(2) Lonoke County $1,200; and
(3) Prairie County $1,000.
(b)
(1) The counties shall pay the above authorized annual amounts in equal quarterly installments from the county general funds of the respective counties.
(2) The payment of each county's pro rata part of the contingent expense allowance shall be upon approval of the county judge of each of the respective counties.