Idaho's hot springs at Lava Hot Springs have drawn people for hundreds, if not thousands, of years as places to bathe, rest, and seek healing and spiritual renewal. For centuries before Euro-Americans arrived, Native Americans from many tribes frequented the area to fish, hunt, enjoy the springs, and use what Shoshone-Bannock Indians call Poha-Ba, or medicine water; minerals and lava rocks from around the thermal pools are still used for ceremonial purposes. The early hot pools were shallow mud puddles where bathers lay in the mud while water trickled over them, and when these pools were deepened they became known as Dempsey's Bathtub, forerunners of the present pools. In the early years, men and women took one-hour turns using a single pool, with men bathing in the nude and women wearing bathing suits, under rules that prohibited splashing and rowdyism. By the late 1920s, facilities included an enclosed natatorium, an open-air pool with a high diving tower, a sanitarium with two pools for men and women, and a mud bath, while the city's Spa Mineral Plunge was a popular pool. The area's several hot springs occur along a north-south fault southwest of town and an east-west fault following the Portneuf River canyon, where rainwater slowly circulates to depths of 8,000-10,000 feet, is heated by molten rock or other subterranean geologic activity, and returns to the surface at a constant temperature of 102º-112º Fahrenheit and 39º-44º Celsius. The odorless, colorless water contains over 16 different minerals, has flowed continuously for 50 million years, and sends nearly 3 million gallons of fresh water through the pools each day into the Portneuf River.