Geothermal Energy in Boise: A Historic Timeline

The Shoshone, Bannock, and Paiute tribes used the region’s geothermal hot springs as neutral territory for warring tribes to negotiate peace. They welcomed traveling indigenous groups to join them there. They considered the underground water’s mineral properties to be healing and used it for bathing, cooking and ritualistic purposes. Winters were a little easier because of the hot water bubbling up along the Boise Foothills. Places such as Eagle Rock (later called Castle Rock by settlers) and the site later known as Kelly Hot Springs were important places within the cultural lives of the local tribes.

Kelly Hot Springs, located on the east side of Table Rock in the area now known as Harris Ranch, was a permanent campsite for the Shoshone, Bannock and Paiute tribes. After the City of Boise was established in 1863, the springs were used by the United States Army as a holding place for the tribes, who spent their last season at the springs in 1869 before being relocated to reservations.

The following spring, J.L. Stephens claimed the land. He opened a spa in May 1871, with showers, a steam bath, and a plunge. At the same time, “omnibus service” from Boise began, offering trips from Boise's city center to the springs every hour.

The springs were sold to Judge Milton Kelly in 1887 and became an exclusive club for Boise’s well-to-do. Kelly soon added a clubhouse and the property became a rumored brothel serving liquor, much to the dislike of Boise’s temperance groups. On October 17, 1906, the property burned down. Arson was the suspected cause of the fire. Warm water still pools there and on cold days motorists can see the steam rising from the old Highland Valley Road.

Two competing companies were formed in June 1890 to supply domestic and fire protection water for Boise. The Artesian Water and Land Improvement Company and the Boise Water Works entered into a highly political water race for a monopoly over Boise's water business.

When the City of Boise granted Hosea and B.M. Eastman a right to lay water pipes in city streets to supply the city with water in 1889, it was not an exclusive franchise. Within a year, the city gave a second franchise to local merchant Nathan Falk. Cut-rate competition and the completion of two 400' deep hot water wells near the Idaho State Penitentiary, where 170°F artesian water was found, gave the Eastmans’ Boise Water Works the competitive edge over Falk’s Artesian Water and Land Improvement Company. In March 1891, the two companies merged to form the Boise Artesian Hot and Cold Water Company and turned its attention to geothermal water.

The company provided hot water to residences along Warm Springs Avenue and also laid pipes along Idaho Street to provide hot water to commercial enterprises. The first pipes were wooden but were abandoned in 1896 as “dangerous and useless.”

This was the beginning of what is now the Boise Warm Springs Water District.

When the Eastman brothers drilled for water, they used cable-tool technology, in which a chisel-shaped drill bit was suspended from a steel cable and repeatedly dropped and raised – typically with muscle power – to drill a hole in the ground. Once the drillers reached the desired depth, engineers slipped a pipe casing into the well to preserve the well hole. Although cable-tool drilling is still used to drill water wells, well-drilling technology has advanced considerably. Today, most rigs are powered by internal combustion engines using rotary drilling methods and a variety of composite drill bits.

The initial natural pressure of the artesian wells was sufficient to force hot water to the top floor of a five-story building. When artesian pressure began to decline, the water district installed pumps. Many of these early wells are still in use today.

The original Boise Artesian Hot and Cold Water Company pumphouse still operates at the base of the Boise foothills near the Old Penitentiary. Its yards and shops were located at 13 ^th  and Front Streets in downtown Boise. By the 1920s, the company was known simply as “Boise Artesian Water Company". The geothermal system, now known as the Boise Warm Springs Water District, was the first of its kind and is the oldest continuously operating geothermal system in the nation. Today, the historic pumphouse and pump works have been preserved and placed on the Department of Interior’s National Register of Historic Places. These historic structures bear testament to Boise’s legacy in pioneering clean energy and the cultural vibrancy of our capital city.

C. W. Moore, the director of the Boise Artesian Hot and Cold Water Company, built a new home in 1892 on the corner of Warm Springs Avenue and Walnut Street. This became the first residential home in the United States heated entirely by geothermal water. Hosea Eastman became the second homeowner to heat with geothermal energy. Soon many homes in the area were able to use the water for heat or simple daily activities like washing dishes or laundry at a rate of $2 per month.

At C. W. Moore’s request, architect John C. Paulsen constructed the Natatorium on Warm Springs Avenue using the area’s geothermal springs to provide a 125’ long pool at 98° F for area residents. Designed in an exotic Moorish style, and featuring a women’s parlor, dining room, saloon, steam rooms, and other amenities, the “Nat” was an important social destination for 40 years. Idaho’s first Inaugural Governor’s Ball for Frank W. Hunt took place on top of the pool in 1901, with a large cover over the pool serving as a dance floor for guests.

The facility’s year-round warmth continued to attract Treasure Valley residents until 1934, when a violent windstorm severely damaged the structure and made it unsafe for use. Unable to raise the necessary funds to repair the Nat during the Great Depression, the city tore down the structure. Today, the site hosts a summer-only public pool that retains the old name, and Boiseans escape the summer heat in its cool waters.

Established in 1891, the Boise Rapid Transit Company extended tracks east on Warm Springs Avenue so citizens could ride out to the newly constructed Natatorium. Located on the edge of town, the Nat inspired the city’s first trolley car system to ferry residents for a nickel to and from the popular social site. With this expanded movement of people, goods and services, Boise’s geothermal resource was the catalyst for successful expansion of the city. The electric streetcar system was one of Boise’s main attractions in the decades straddling the turn of the 20 ^th  century. Citizens used the trolleys for practical reasons as well as pleasure. The Nat remained a beloved destination even after the trolley system ran its last car down Warm Springs in the late 1920’s and was replaced by the automobile.

Established during the summer of 1930, Edwards Greenhouse, near Hill Road in northwest Boise, became the first commercial greenhouse in the United States to utilize geothermal water to cultivate vegetables and plants. Using a geothermal well drilled on their property, Edwards Greenhouse supplied local grocery stores with vegetables until 1970, when the greenhouse became a full-time retail business. Today, Edwards Greenhouse utilizes geothermal water almost exclusively to grow a variety of vegetables, seasonal potted plants, bulbs, and a wide variety of annual and perennial flowers through all four seasons.

Skyrocketing gas prices during the 1970’s oil crisis spurred Idaho to investigate developing its geothermal resources to their fullest potential. The State of Idaho Capitol Mall Complex was expanding, and Governor Cecil Andrus requested a federal study to determine the feasibility of geothermal heat for the State’s buildings. Boise State University sponsored a project that mapped the Treasure Valley’s hot water aquifer. The Department of Energy constructed a demonstration site in 1979 near Raft River to assess geothermal use for power production. Research steered Idaho’s development of this valuable resource of alternative energy as the nation sought to develop domestic energy resources.

Today, the Idaho State Capitol is the only geothermally-heated state capitol in the nation.

In response to diminishing geothermal water supplies, the City of Boise built a well to inject spent water from its hot water heating system back into the geothermal aquifer in 1998. Today, spent water is reinjected through a 3,213' deep well in Julia Davis Park. This injection well makes the City of Boise's geothermal heating system a closed loop, returning 100% of the water to replenish the aquifer and sustain its use for years to come. It also benefits the Boise River by reducing warm water discharge, which helps maintain the cool water temperatures critical to healthy river habitat.