According to the United States Census Bureau, the city has a total area of 1.7 square miles (4.4Square kilometers), of which, 1.3 square miles (3.4Square kilometers) of it is land and 0.4 square miles (1.0Square kilometers) of it (22.81%) is water. Nassau Bay is a city in Harris County, Texas, United States, bordering the southeastern edge of the city of Houston. It is located in the Clear Lake Area near Galveston Bay, directly adjacent to the Lyndon B. Johnson Space Center. The population was 4,170 at the 2000 census. The current mayor is Donald Matter.