In this subtitle the following words have the meanings indicated. “Commissioners” means the Board of County Commissioners of Calvert County, Charles County, or St. Mary’s County, respectively. “Council” means the Tri-County Council for Southern Maryland. “Executive Director” means the Executive Director of the Council. “Plan” means a regional plan that the Council prepares for the region. “Region” means Calvert, Charles, and St. Mary’s counties.