Lava Hot Springs is a city in Bannock County, Idaho. It is part of the Pocatello, Idaho Pocatello, Idaho metropolitan area. The population was 407 at the 2010 census, down from 521 in 2000. Located in the mountainous valley of the Portneuf River on the old route of the Oregon Trail and California Trail, the city has become a popular resort location, noted for its numerous hot springs amenable to bathing and a turbulent inner tube run through part of the town.