The compensation to each board member and all other expenses of the board arising under this subpart shall be paid from funds of the county on the order of the board in the same manner as other county salaries and expenses are paid. At the end of the county's fiscal year, the board shall prorate the total sum which it has expended for the purposes of this subpart between the county and the municipalities subject to this subpart, charging each with such part of the total sum so expended as the total number of officers or employees of such county or municipality who were subject to this subpart on the last day of the county's fiscal year bears to the total number of officers or employees of the county and municipalities subject to this subpart on such last day of the county's fiscal year. The sum so arrived at by the county as the proper contribution of each shall be certified to the chair of the board and when approved by him or her in writing, shall become a liability of the county or respective municipality, and shall be paid immediately to the county. In the event any contribution levied hereunder shall not be paid within 30 days after approval by the board chair, the county may bring suit therefor in any court of competent jurisdiction and any judgment so recovered shall be satisfied from any funds in such treasury or funds against which such contribution levy lies. In the event the salaries of employees of the county or municipalities are paid in part from different treasuries or different funds in the same treasury, the liability for this contribution shall accrue against such various treasuries or funds in the same proportion as the salaries of the employees of the county or municipality are paid therefrom.