Electricity and Mining

The steel transmission towers extending across the Butte Hill, just south of the intersection of North Idaho and Pacific, are part of a transmission line running from Great Falls to Anaconda. The towers date from 1910, when the Rainbow Falls dam and power plant at Great Falls went into service to supply ACM’s operations at Butte and Anaconda. All the transmission towers across the Butte Hill once looked like this, but Northwestern Energy is gradually replacing the 1910 transmission towers with two-pole wooden structures with horizontal cross-arms. Long-term survival of the remaining 1910 transmission towers is uncertain. Source: Photo by Fred Quivik, July 2024.

The first couple decades of Butte’s mining boom were based on the technological advancements of the Industrial Revolution: burning coal, using steam to generate mechanical power, the linking of urban markets to remote regions like Butte by means of the railroad.

Butte copper then helped supply the wiring for the Second Industrial Revolution, which was based in part on electrification. After a slow start in electrifying mining operations in the late nineteenth century, Butte engineers developed many ways in the early twentieth century to use electricity to greatly lower mining costs.

The Alice Silver Mining Company was the first Butte company to install electric lights in its mine and mill. Installed in late 1880, it was the technology of the Brush Electric Lighting System, which used electric arcs between two carbon electrodes, rather that the incandescent light bulbs that Thomas Edison would introduce two years later. Although Butte had an electric lighting company supplying electricity to customers in the central business district by 1884, most mines that installed arc lighting in the wake of the Alice’s introduction owned their own generating plants at their mineyards. Butte and its mines continued to be serviced with electricity generated with coal-fired steam until the turn of the twentieth century, when three hydroelectric generating stations started transmitting power to Butte from dams on the Big Hole River, the Missouri River at Canyon Ferry, and the Madison River near Ennis. By this time, mines were also using electricity for tramming ore and pumping water from the mines. The next big plant built to supply the mining industry at Butte with electricity was the Missouri River Power Company, which operated the Canyon Ferry dam. It built the Hauser dam and generating station north of Helena in 1907. Disaster struck that company in April 1908, when a flood washed out the dam.

Meanwhile, John D. Ryan, president of Amalgamated Copper Company, the holding company that by 1908 owned Anaconda Copper Mining Company (ACM) and most of Butte’s other large mining companies, was negotiating to gain control of the rights to the hydropower sites along the Missouri River at Great Falls. There, the Black Eagle Dam was already supplying electricity to the Great Falls smelter of the Boston & Montana Consolidated Copper & Silver Mining Company (one of the Amalgamated companies). As engineers for Amalgamated and ACM were investigating how to reduce costs at Butte and Anaconda by expanding the uses of hydroelectricity, Ryan moved to build a new dam and generating station at Rainbow Falls, just below Great Falls. To convey electricity from Rainbow Falls to Butte, the Great Falls Power Company built a 130-mile transmission line, completed in May 1910. The 102 kilovolt transmission wires are supported by steel towers built in tandem so that, if lightning knocked out the power on one set of lines, the other set of lines could still supply the mines and not interrupt operations.

Much of that transmission line is still visible on the Montana landscape. Close to Butte, the double sets of 1910 transmission towers, which are visible from I-15 in Elk Park, embody the way ACM incorporated vast areas of Montana into the company’s technological system. Most of the electricity from Great Falls was used at the mines for hoisting, operating rock drills, and running pumps and ventilating fans, but nearly half of the electricity was sent on to Anaconda for use at the smelter for powering the machines in the concentrator, running blowing engines, and operating cranes and other power equipment. Some of the transmission towers of that line to Anaconda still stand on the Butte Hill, and along Montana Highway 1 from I-15 into Anaconda. Shortly after completion of the Rainbow Falls dam and powerplant, Ryan was able to consolidate the Great Falls Power Company, the Missouri River Power Company, and other systems to form the Montana Power Company (MPC, predecessor of Northwestern Energy), establishing the once-close relationship between MPC and ACM.