Ottawa is a town in Waukesha County, Wisconsin, United States. The population was 3,758 at the 2000 census. The town is named after the Ottawa, a Native American tribe. According to the United States Census Bureau, the town has a total area of 34.9 square miles (90.4 km²), of which, 34.3 square miles (88.9 km²) of it is land and 0.6 square miles (1.6 km²) of it (1.75%) is water. As of the census of 2000, there were 3,758 people, 1,375 households, and 1,112 families residing in the town. The population density was 109.5 people per square mile (42.3/km²).