About 10 years after California’s Gold Rush, a new wave of get-rich-quick prospectors flocked to northern Nevada’s high desert, then part of the Utah Territory. They hoped to cash in on a different precious metal: silver. Miners faced dangerous conditions, including cave-ins and toxic air. In what was known as the Comstock Lode, they also had to deal with a geothermal aquifer that filled the mines with gallons of scalding-hot water. As the mines grew ever deeper, their pumping systems proved no match for the unrelenting waters.

Enter Adolph Sutro, a Prussian immigrant, self-taught engineer, and entrepreneur who made a living selling cigars and tobacco in California. Sutro, who had observed drainage adits, or tunnels, in Europe, proposed building a nearly 4-mile-long adit that could transport millions of gallons of water out of the mines on a daily basis. He started selling stock certificates in his Sutro Tunnel Company to raise funds for construction, which began in 1869. (Individual miners also put up seed money for the project.)

When completed in 1878, the Sutro Tunnel was nothing short of an engineering marvel: Work crews, consisting of immigrants from around the world, had dug and blasted through the terrain and constructed a roughly 17-foot-wide-by-20-foot-tall tunnel. Larger rooms were interspersed throughout the passage, all the way from the mouth of the tunnel near Dayton, Nevada, to the Savage Mine under Virginia City, Nevada. More than 4 million gallons of water flowed daily through wooden flumes, and later metal pipes, while mules pulled carts along tracks, transporting silver ore out of the tunnel. Ventilation shafts spaced throughout provided access to fresh air. The Sutro Tunnel was such a wonder that former President Ulysses S. Grant took a joyride through it in 1879.

But by the time the tunnel was completed, production at the Comstock Lode had already peaked. Sutro, whose wealth had grown from the sale of stock certificates and the fees collected from the mining companies that used his tunnel, moved back to San Francisco and became its 24th mayor. He employed his knowledge of water engineering to build the famed Sutro Baths. The town of Sutro, Nevada, which was founded during the tunnel’s construction, was abandoned over time; use of the tunnel dwindled until all non-essential mining ended in 1942. Today, a handful of original buildings around the tunnel’s portal remain, as does a pond, which Sutro built to accommodate the millions of gallons of water drained from the mines.

In the early 2010s, a group of history-minded volunteers began fixing up the buildings—a warehouse, a mule barn, a woodshop, a carriage house, and a “candle and tag” building where miners would pick up their lights and sign in for the day’s work. Several years later, an informal group of volunteers came together and were eventually joined by local business leaders. The group evolved into a nonprofit, Friends of Sutro Tunnel, which hired its first site manager and executive director, Chris Pattison, in 2021. Pattison knew the tunnel was collapsed and would be costly to reopen, but as he says, “I had a few ideas.”

Pattison’s first idea was to explore the adit with drones, a privately funded project. The drones traveled about 300 feet into the opening before losing their signal. Images revealed collapsed timber framing throughout, but the passageway appeared to be sound enough to potentially reopen.

After tracking down the original plans, Pattison’s next idea was to restore the tunnel as closely to Sutro’s original design as possible.

Construction crews are rebuilding the wood framing, working beneath a 10-foot-tall protective metal cage dubbed “the turtle” that is inched along as work progresses. Pattison says every 5 feet of headway costs about $8,000, money he and others have raised through private donations, site rental fees, tours, fundraisers, and merchandise sales. Currently, the first 50 feet of the tunnel—and several original buildings—are open for public tours. While volunteers continue to rehab the outbuildings, construction on the tunnel starts and stops as donations come in.