Each commissioner shall receive a salary at the rate of fifteen hundred dollars per annum from the time of appointment until the execution of a contract for a water supply with any municipality, which salary shall be accumulative and payable upon the execution of any such contract, and thereafter each commissioner shall receive a salary at the rate of $7,500.00 per annum payable monthly, except the chairman of the commission, chosen as hereinafter provided, who shall receive a salary at the rate of $8,500.00 per annum. Such salaries shall be charged as an expense of the development and operation of any water supply contracted for hereunder.
N.J.S. § 58:5-4