ORS § 268.220
Except as otherwise provided by ORS 268.230, a district shall offer to employ every person who, on the date the district takes over a function of a public corporation, city or county in the district, is employed by the corporation, city or county to carry on the function. Where the district employs such a person, the employee shall remain an employee of the corporation, city or county for purposes of any pension or retirement plan the employee has been included in by the corporation, city or county and shall continue to have rights and benefits thereunder as if the person had remained an employee of the corporation, city or county, until the district provides a similar plan for its employees and the employee is included in the plan. Until the employee is so included, the district shall deduct from the compensation of the employee the amount the employee is required to pay under the plan of the corporation, city or county; shall pay that amount to the corporation, city or county, which shall credit the amount to the employee under the plan; and shall make whatever payments the plan calls for the employer to make.
ORS 268.220