The state shall be represented on the New England Interstate Water Pollution Control Commission by five commissioners to be appointed by the Governor. One shall be the Commissioner of Environmental Conservation, one shall be an officer of the Department of Environmental Conservation and the others shall be such persons as the Governor shall determine will serve the best interests of the state. The commissioners shall serve during the pleasure of the Governor. They shall have all the powers and duties enjoined by the compact; shall serve without compensation, but shall be reimbursed for their expenses actually and necessarily incurred by them in the performance of their duties. The traveling expenses of the commissioners in attending meetings of the commission shall be paid on the audit and warrant of the Comptroller upon vouchers approved by the Department of Environmental Conservation from funds appropriated to the Department of Environmental Conservation for such purposes. The Commissioner of Environmental Conservation and the officer of the Department of Environmental Conservation may designate, from time to time, a deputy or other subordinate in his department to attend and participate in any meeting of or hearing by or other proceeding of the commission, with authority to vote as a representative of or substitute for said commissioner or officer of the Department of Environmental Conservation.