(1) A district may establish an employees’ retirement system pursuant to ORS § 478.355 to 478.370. The board may enter into agreements necessary to establish the system and carry out the plan and may agree to modifications of such agreements from time to time.

(2) The retirement plan may provide for retirement benefits measured on the basis of services rendered or to be rendered by an employee, either before or after the date on which such employee first becomes a member of the retirement plan. The retirement plan may provide for a minimum of years of service and a minimum and maximum age of retirement for the employee. [1963 c.366 3,4; 1969 c.667 § 25]