In 1890 well drillers found 177-degree water pure enough for domestic use near the state penitentiary in Boise.
The water was first used to create a hot water resort. Boise's beautiful natatorium was opened in May of 1892 to the delight of swimmers and soakers . That same year, C.W. Moore decided to put the hot water to another use. He piped it into his home to provide heat. The system worked well, and H.B. Eastman, who had built a mansion nearby, began to use geothermal heat. Others along the street saw the advantage, and a community heat line was built, using wooden pipe at first. It cost two dollars a month to heat an eight-room house--three dollars would heat the larger ones along Warm Springs Avenue in Boise...You've probably already figured out why the street was named that.
The system is still in use today, and it's been expanded to include more homes, apartments, and businesses. Boise City Hall, the Ada County Courthouse, Idaho's statehouse, and much of Boise State University are on the geothermal system. It was the first system of its kind in the United States.