The board shall establish rules for its proceedings. There shall be at least four meetings per year. Board members shall be entitled to one hundred fifty dollars ($150) per diem from authority funds, for each board meeting attended and the authority may pay per diem to board members attending meetings of committees of the board except that per diem for attending board meetings and board committee meetings shall not exceed the sum of two hundred dollars ($200) per month, plus actual expenses incurred in attending meetings at rates payable to county officers and employees. The per diem rate of one hundred fifty dollars ($150) may be increased by the board subject to approval by the boards of supervisors.