(a) There are created within the division regional mental health, mental retardation, and substance abuse planning units. The number of those units and the regions within which they shall operate shall be established from time to time as necessary by the board. In accordance with Code Section 37-2-3, the board shall initially establish the boundaries of each region based on the recommendations of the State Commission on Mental Health, Mental Retardation, and Substance Abuse Service Delivery pursuant to Code Section 37-2-34; provided, however, that any county with a population of 400,000 or more as of the United States decennial census of 1990 or any future such census may not be combined with any other county for the purpose of creating such a region without the approval of the county governing authority.

(b) There is created a separate regional mental health, mental retardation, and substance abuse board as the governing body for each regional planning unit established under subsection (a) of this Code section. Each such board shall provide and facilitate coordinated and comprehensive planning and service delivery for its region in conformity with minimum standards and procedures established by the division. Each such board shall be designated with such identifying words before the term "regional mental health, mental retardation, and substance abuse board" as that regional board may, from time to time, choose and designate by official action.