Lacombe is a census-designated place in St. Tammany Parish, Louisiana, United States. The population was 8,679 at the 2010 census, and 8,657 in 2020. Lacombe is located at 30°18′54″N 89°55′53″W / 30.31500°N 89.93139°W. According to the United States Census Bureau, the CDP has a total area of 27.5 square miles, of which 26.4 square miles is land a…Lacombe is a census-designated place in St. Tammany Parish, Louisiana, United States. The population was 8,679 at the 2010 census, and 8,657 in 2020. Lacombe is located at 30°18′54″N 89°55′53″W / 30.31500°N 89.93139°W. According to the United States Census Bureau, the CDP has a total area of 27.5 square miles, of which 26.4 square miles is land and 1.0 square mile, or 3.86%, is water.