Folsom Powerhouse State Historic Park

The Folsom Powerhouse stands on a bluff above the west bank of Lake Natoma. It is a two-story building of red brick on a granite foundation, with walls 20 to 30 inches thick under a gable roof of corrugated metal. Inside, four General Electric generators sit where they were set in 1895. The 1978 National Register nomination gives each as 8 feet 8½ inches tall and 57,877 pounds, and says they came to California by ship around Cape Horn. Near them are the wooden flumes and a control switchboard faced with Tennessee marble.

Outside stand the transformers, each able to carry from 800 to 11,000 volts, and the forebay, 150 by 100 by 12 feet. River water once came to rest in the forebay long enough to drop its sand and gravel. Then it fell 55 feet through eight-foot penstocks to the turbines.

Below the powerhouse, at the edge of the lake, is a grinding rock the Maidu used to prepare acorn meal. The park brochure says the Southern Maidu lived here long before Europeans arrived, on a river that gave them fish, birds, deer, roots, fruits and nuts. Placer-mining features in the ground also predate the plant. Daniel A. Bell, the park’s associate state archaeologist, writes that no evidence yet shows whether they reach back to Negro Bar, the mining camp of 1849 to 1854 just downstream. In 1856 the California Central Railroad laid its track along the east side of the site, roughly where Riley and Leidesdorff streets run now.

Guides in the generator room

Staff interpreters and volunteer docents lead the tours. Ed Goldman described one Saturday afternoon tour in Comstock’s magazine in December 2025. His guides were Nicole Barden, a State Parks interpreter, and Kevin Sigl, a retired electronic engineer who spent 20 years at Hewlett-Packard. Sigl said that career “doesn’t qualify me for this job.”

Sigl explained turbines, generators and a rope. The rope is thick, 2,200 feet long, and still coiled on an enormous reel. The guides said it opened and shut the gates that let American River water through the dam into the forebay. “This rope isn’t the original rope,” Barden said. Vandals had cut pieces from the old one some years ago and carried them off. The National Register nomination gives a 2,200-foot rope a different job. It says some 2,200 feet of continuous-strand hemp once linked turbine and generator in the lower powerhouse, a second plant built below the main one in 1897.

The guides are quick to say Folsom was not the country’s first alternating-current station. “There was also a little something called Niagara Falls,” Sigl said. Of the machinery, Barden said, “It would cost a fortune to put any of this back into operation.” The tour passes an enormous switch whose flip could turn the power on or off in Folsom, Sacramento and the communities around them.

The guides also tell of electrocutions. A few were fatal, and one sent a worker flying through the air to land intact. They tell of a severed leg as well. “The supervisors probably came from other power companies,” Sigl said. “But the average day worker was just that: a day worker.” He added, “This wasn’t a popular place to work because of the danger and the strangeness of it. You’d be better off getting a job on a farm or at a store in town.”

Up the slope, an airy visitor center uses words, pictures and historic photographs to show how streetlights were powered and trolleys ran. In 2024 about 30,000 people came to the visitor center, the powerhouse, or both.

The park holds events through the year:

• Biodiversity Week: On September 5, 2026, the park hosted the opening of the California Natural Resources Agency’s Biodiversity Week. Groups walked the grounds logging plants and animals on the iNaturalist app.
• Electricity Fair: The 13th annual fair, put on with the Sacramento Municipal Utility District, is set for October 17, 2026, from 10 a.m. to 3 p.m. It offers powerhouse tours, solar art, hydropower lessons and hands-on science, with free SacRT rides for those who show the flyer.
• Powerfest Taps & Tunes: The Friends of the Folsom Powerhouse hold this event at the park.

A Lowell on the American River

The plant began with Horatio Gates Livermore, a Maine man who came to California in 1850 looking for gold. According to the National Register nomination, he won a seat in the state senate. On his trips to Sacramento he came to think the American River could serve logging and industry. He dreamed of an industrial city at Folsom like Lowell, Massachusetts, with logs floated down to sawmills and factories driven by the river.

Accounts differ on the timing that followed:

• The nomination: His sons, Horatio Putnam and Charles Edward, joined him in 1856. By the mid-1860s the family controlled the Natoma Water and Mining Company and had added some 9,000 acres of the former Rancho de los Americanos.
• The park brochure and the IEEE milestone record: Father and sons held the company by 1861.

The Natoma company’s dams, ditches and reservoirs fed the gold mines along the river.

Livermore’s plan needed a dam at Stony Bar Gorge to hold the logs. Work began in 1867, and the company spent some $119,000 on a two-mile railroad to the dam site and on the dam’s foundation. Then the state went looking for a prison site. The nomination says the Livermores agreed to give 350 acres beside the dam for a prison in exchange for $15,000 worth of convict labor on the dam and a power canal.

Convicts started on the dam in July 1882, a year after Natoma became the Folsom Water Power Company. Work went fairly smoothly under the engineer H. T. Knight until about 1888. That year the company decided it was owed more labor and stopped. The state sued. The compromise gave the company more labor, later valued at over $200,000, and gave the prison more water rights. The nomination form, as quoted by the American Society of Civil Engineers, says “the work progressed slowly during the dry season by disinterested convict labor using hand tools since the use of machinery was forbidden.”

The finished dam was granite masonry, 650 feet long and 87 feet high, built of 78,500 cubic yards of stone set in mortar from 20,000 barrels of cement. The sources disagree on when it was done:

• The nomination: Dam and canal were completed in 1892, the year the elder Livermore died.
• The park brochure: He died in 1879, and Horatio Putnam finished the dam and canal in 1893.

The park’s own history gives 1893 for the canal. That year Folsom State Prison became the first to use the dam, starting a hydroelectric plant of its own.

Eleven thousand volts down the line

The sawmill venture lost money, the brochure says. The nomination says reports of European experiments convinced the sons to send electric power the 22 miles to Sacramento instead. In 1892 they joined with Albert Gallatin, president of Huntington, Hopkins Hardware, to form the Sacramento Electric Power and Light Company to sell the power.

Horatio Putnam Livermore took designs from both Westinghouse and General Electric. The sources give different reasons for choosing GE:

• The brochure: GE was willing to fund construction bonds.
• The IEEE record: GE made better use of three-phase current.
• The nomination: Gallatin persuaded GE to invest.

The IEEE says Elihu Thomson, Charles Steinmetz and Louis Bell built the four three-phase, 60-cycle generators at Schenectady, and that Bell designed the line to Sacramento. The brochure says Thomson reworked four Edison direct-current machines into the new generators. In September 1895 the Journal of Electricity called them “without doubt the largest three-phase dynamos yet constructed.”

On July 13, 1895, with only two generators running, current went over uninsulated copper wire to Station A, a substation at Sixth and H streets in Sacramento. The San Francisco Chronicle reported: “It was 4 a.m. in Sacramento when a 100 gun salute shattered the quiet. People not planning on getting up early that morning never forgot it.” The park says a detachment of soldiers near the substation fired the salute. The sources rank the achievement differently:

• The IEEE: Folsom was the first plant to use three-phase, 60-hertz current, which became the national standard.
• The ASCE: Folsom was the second American system of its kind, after Mill Creek No. 1 near Redlands, finished two years earlier.

Sacramento set its “Grand Electric Carnival” for September 9, Admission Day. The brochure counts 30,000 visitors from San Francisco alone; Comstock’s gives an estimated 30,000 in all. Lights outlined the Capitol and the ribs of its dome, where a cluster of arc lights could be seen for nearly fifty miles. Floats lit with bulbs or carrying machinery moved behind electric trolley cars. Comstock’s adds that a Disneyland employee, willing to talk on background, may say the carnival inspired the later spectacles at the Disney parks in Anaheim and Florida.

The power ran the Central Pacific Shops, the Phoenix Gristmill, the Buffalo Brewery and the Capitol. Streetcar lines grew from four miles to forty, and the breweries gained refrigeration. Homes used little of it.

Fifty-seven years and a new dam

Trouble came early:

• 1896: The Livermore companies were merged into the Sacramento Electric, Gas and Railway Company.
• 1896 to 1898: Dry years left the river too low to meet the city’s needs.
• 1897: The lower powerhouse went in at the tailrace mouth, with one 750-kilowatt generator turned by a rope drive. The nomination and the ASCE give it a 26-foot drop; the park history says 25.
• 1901: A generator ran away and shattered its armature. River sediment wore down the turbine blades on a regular basis.

When the river failed, the Livermores bought power from the Colgate plant on the Yuba River. In 1903 they and Gallatin sold out to California Gas and Electric, owned by Eugene de Sabla and John Martin; the park history dates the acquisition 1902–1903. The company was reorganized as Pacific Gas and Electric in 1906 and kept the plant from then on.

PG&E kept updating the plant:

• 1906: New governors went in, with new transformers on the second floor.
• 1916: Sacramento County built a concrete bridge over the mouth of the forebay. Iron railings and lights around the forebay probably followed.
• 1918, or just after: Four large transformers and three oil switches were set north of the powerhouse, and an office and machine shop went up on the hill.

The lower plant’s end is told two ways. The ASCE says it went off-line in 1920. The park history says it got a new generator in 1923, ran only briefly, and shut down for good in 1924.

The main plant ran until November 1952. That year the old dam came down for the new Folsom Dam. In 1958 PG&E gave the powerhouse and about half a mile of canal to the state. A landmark plaque, California No. 633, was placed on August 22, 1958, and the California Historical Society dedicated the site on September 9, 1958.

History panels went into the shop building’s garage in the late 1960s or early 1970s. Around 1980, staff began repairing damage from vandalism and neglect, and three preservation projects were finished between 1987 and 1990. Engineering societies named the plant a civil engineering landmark in 1975 and a mechanical engineering landmark in 1976. It was listed as a National Historic Landmark and on the National Register in 1981.

On July 13, 2021, the IEEE dedicated its bronze milestone plaque, No. 218, on a granite boulder near the powerhouse. The 1958 state plaque is mounted on a shorter boulder to its right.