Springdale is a city in Hamilton County, Ohio, United States. It is a suburb of Cincinnati. The population was 11,007 at the 2020 census. Accordi…Springdale is a city in Hamilton County, Ohio, United States. It is a suburb of Cincinnati. The population was 11,007 at the 2020 census. According to the United States Census Bureau, the city has a total area of 4.97 square miles, of which 4.96 square miles is land and 0.01 square miles is water.