(a) Except as provided in subdivision (b) of this section, at least 50 percent of the expenditures by an area agency under its supportive services program, excluding amounts used for administration, must be made on the following services, with an adequate proportion spent in each category:

(b) The office may waive this requirement only if the area agency demonstrates that the needs of elderly people in the area for one of these categories of service is being met from other sources. If the office grants a waiver, the area agency must spend an agreed percentage of its OAA supportive services allotment on the other two priority service categories. Before an area agency requests a waiver under this section, the area agency shall conduct a timely public hearing, shall notify all interested parties in the area of the public hearing and furnish the interested parties with an opportunity to testify, shall prepare a record of the public hearing, and shall furnish the record of the public hearing to the office with the request for a waiver.