Mike McCartan may soon be stepping down as St. Clair County Community Mental Health Executive Director, a position he has held for the past 27 of the 37 years he has been with CMH.   McCartan says he has been preparing the agency for the past three years for his retirement, and board members have been meeting the past three months to decide what they would like to see in a replacement.  His contract runs through December of this year, and McCartan says, if need be, he can stay longer to allow for an appropriate transition.  St. Clair County Community Mental Health provides mental services to residents with a developmental disabilities, mental health issues or substance abuse issues. The agency provides outpatient programs, and contracts out residential programs, group homes, foster care homes, day programs and home-based services for children.