Gold Mining on the Yankee Fork
Roughly thirteen miles northeast along Idaho Highway 75 from Stanley, Idaho, “the gateway to the Sawtooth Wilderness,” is a turn-off for Yankee Fork Road. At this junction, the Yankee Fork of the Salmon River, a 28-mile tributary, empties into the Salmon River and the reminiscences of the Sunbeam Dam, which powered the Golden Sunbeam Mine and machinery from about 1909-1910, are visible to motorists. These scenic and historic elements are usually enough to warrant a stop and bathroom break, but for those adventurous enough to follow the partially paved Yankee Fork Road eight miles north, you will see the physical reminders of an era of Idaho’s mining history that had particularly visible impacts. Keep reading to learn more about central Idaho’s mining history and how the Yankee Fork dredge changed a five-mile stretch of a riverbed in Custer County.
Mining in what would become Custer County did not begin until the 1870s, nearly a decade after Idaho’s first gold rush. During the first half of this decade, placer claims (mining claims for ore found on the ground surface, under a thin cover of soil, or in stream beds) along Jordan Creek, a Yankee Fork Tributary, produced only a modest yield. In 1875, however, miners discovered a lode claim (mining claims for mineral deposits lying “in place” within veins of quartz or other rocks) that produced nearly $12,000 in a single month by hand-mortar separation methods. Between 1876 and 1879, this claim produced roughly $133,000, equating to nearly $4 million in today’s dollars. The claim’s success led to the formation of the towns of Bonanza in 1877, Custer in 1879, and the creation of Custer County in 1881.1
From the 1880s through the turn of the century, mining continued along the Yankee Fork. However, miners soon exhausted the easiest claims, and mining activity and the population decreased. By 1911, Bonanza, which had maintained a population of 2,000 people at its height, was a ghost town. With the rise in popularity of the automobile during the early 20th century, central Idaho’s beauty began to attract visitors, and rustic amenities, such as the newly completed lodge and gas station at Red Fish Lake, located less than thirty miles south of Bonanza, moved Idahoans to begin thinking of Custer County’s wealth in new ways. Nevertheless, at the same time, new interests armed with refined technologies again turned their attention to the Yankee Fork.
The new technology that allowed for the continued mineral exploration along the Yankee Fork was the dredge—a device first developed in Europe during the 16th and 17th centuries. In simplest terms, a dredge is a large floating device designed for a specific location and its unique attributes—think stream conditions or bolder size—to mine sediments deposited from flowing water. The dredge digs up the sediment at the bottom of the riverbed seeking the smallest pieces of gold that had settled, sifting these materials out of the gravel, rocks, and sand, and then depositing the tailings in large piles in its wake.2 These large mounds of rocks and sediment in the wake of the Yankee Fork dredge are still visible along Yankee Fork Road today.
In April 1940, the Snake River Mining Company, a subsidiary of the Silas-Mason Company—the consolidated interests of the Yankee Fork claims—contracted with the Bucyrus-Erie Company to design and build its Yankee Fork gold dredge at an estimated cost of nearly $350,000.3 The process required multiple subcontractors and engineers, but the results produced a highly automated dredge with hydraulic levers that “at a touch could move and control the dredge’s digging operations.”4 However, once in operation, the dredge proved that it was not infallible. For example, during the first use season, many pipes froze and needed to be replaced entirely, and the original fuel supplied caused corrosion to the engine. Despite these setbacks, the Yankee Fork dredge operated between 1940 and 1953, with only a few periods of closures due to WWII and a lack of parts. During this time, it extracted over $1.02 million worth of gold while employing hundreds of people and supporting towns in Custer County.
By 1953, the Yankee Fork Dredge had worked the entirety of the original Yankee Fork mining claims and some land on an adjacent claim! Then-owner J.R. Simplot, who had acquired partial ownership in the Yankee Fork mining interests in 1949, decided to turn the dredge around, ensuring it sat entirely on his claim, locked it up, and walked away. On December 18, 1967, Simplot donated the dredge and the one acre of land on which it sits to the U.S. Forest Service. Nearly fifteen years later, the Yankee Fork Gold Dredge Association formed and began providing guided tours of the dredge to the public. The Yankee Fork Gold Dredge remains one of the best-preserved dredges in the continental United States. As of June 2021, the National Park Service listed it in the National Register of Historic Places under Criterion A in the area of Industry and Criterion C in the area of Engineering. Next time you are in Custer County, exploring Idaho’s Alps – the Sawtooth Mountains and experiencing all the scenic beauty, take the turn onto Yankee Fork Road and venture back in time to see the Yankee Fork dredge to learn more about Idaho’s mining history.
Written by State Historian HannaLore Hein
Burk-Hise, Kathryn. “Yankee Fork Gold Dredge.” National Register of Historic Places Registration Form, On File at Idaho State Historic Preservation Office. Idaho State Historical Society. Boise, Idaho, June 17, 2021.
Major, Kris. “The Yankee Fork Dredge and Its Community.” Idaho Yesterdays 32, no. 2 (June 1, 1988): 22–34.
Stephens, George C. “A History of Gold Mining on the Yankee Fork River, Custer County, Idaho.” Bulletin. Guidebook to the Geology of Central and Southern Idaho. Moscow, Idaho: Idaho Geological Survey, University of Idaho, 1991.
60-99-49 – Yankee Fork Dredge, Idaho State Archives
72-201-97 – Yankee Fork Dredge, Idaho State Archives
442-1, Custer, Idaho, 1880, Idaho State Archives