A Gargantuan Gold Dredge

With clear weather forecast for the next few days, I ventured deeper into the mountains toward the ghost towns of Custer and Bonanza. Following the Yankee Fork of the Salmon River north, I passed a tall cottonwood tree standing by the roadside. Its trunk, gnawed halfway through, must have been no match for the local beaver population. The notch was on the roadside and a few inches wide, suggesting that the tree would soon fall at some random moment. It almost felt as though the beavers were taking revenge for the disturbances humanity had caused over the past century and a half.

I quickly moved past the tree and soon found myself surrounded by the remnants of old mining operations—piles of tailings scattered throughout the small valley. An old wooden sign marked the site where the Yankee Fork Dredge had begun operations in the fall of 1939, producing the very tailings now in front of me. Another sign indicated that a restoration project was underway, aiming to return the Yankee Fork riverbed to its original state so that Chinook salmon, steelhead, bull trout, and other species could once again migrate as they had before the dredge. The project planned to preserve many of the tailings piles, which reassured me that conservation was being thoughtfully balanced with historical preservation.

Looking north across piles of snow-covered dredge tailings

The whole area and streambed were lined with piles of smooth stones, some larger than bowling balls, stretching nearly six miles upstream to the dredge. Tearing such massive stones from the earth required an enormous machine. The Yankee Fork Dredge, over 110 feet long and 50 feet wide, used a massive conveyor belt made of cast buckets—each nearly a ton in weight. As the dredge floated on the flooded earth, it churned through the soil, tearing it apart with relentless force. Behind it, rhythmic piles of tailings—rocks of all sizes—were deposited through chutes and a conveyor. The heaps formed wavelike ridges, their peaks and valleys evenly spaced, as if shaped by some unseen, giant hand.

A small cabin near the outskirts of Bonanza

A couple of miles further, and I reached the ghost town of Bonanza. The remnants of the town sat off to the left side of the road, nestled in a flat valley. I parked the truck and stepped out, eager to explore the history hidden within the ruins. A cabin near the road still stood in surprisingly decent condition. The gaps between its logs were covered with tin—an unusual choice I hadn’t encountered before, as most cabins typically used mud, cement, moss, or clay to seal the spaces.

The snow around town was a couple of feet deep, but I tested it in several spots and deemed it passable for the truck. Climbing back in, I shifted into gear, and the tires rolled smoothly as the front of the truck gently pressed into the fresh powder. I slowly navigated the camper up the hill toward what was supposed to be a campground. At the top, I found a ranger station and a few government storage buildings. There was also a large, vented wooden box that appeared to be used for birds, perhaps for falconry—another small mystery to ponder. As I moved forward, the pines thickened, and the narrow side valley stretched westward. Intrigued, I continued on, determined to find the cemetery and learn more about the men and families who had once called Bonanza home.

Gravesites in Bonanza Cemetery

Bonanza was founded in 1877 by Charles Franklin, who had recently come from the booming mining town of Bodie, California. As the first settlement in the new mining district, Bonanza grew quickly when Franklin began selling lots for as much as $300 that summer. By 1881, the town had swelled to over 600 residents and boasted more refined establishments, including a dentist, a watchmaker, and even a local newspaper, The Yankee Fork Herald.

According to the Idaho Parks Department’s Land of the Yankee Fork Historical Area in Words and Pictures, Bonanza was a unique town. Unlike many other mining towns, it lacked the noise of mills or the mess of mines within its limits. Three bridges crossed the Yankee Fork River, and the town offered recreational amenities such as a baseball field, a croquet court, and a small racetrack. Its tree-lined streets, coupled with a public water system, gave it an almost idyllic atmosphere.

But in 1889, a devastating fire swept through the town, changing everything. In its wake, many residents relocated just up the road to the newer town of Custer. Some buildings were even moved, and within just a few decades, Bonanza had largely emptied out. Today, little remains of the once-thriving town except for the cemetery, which still sits on the hill. I made my way to it through a scattering of trees, a quarter of a mile from where the town once stood.

At the entrance, a sign displayed the names of over 80 individuals buried there, along with brief notes about their lives and contributions to Bonanza. It was the first sign of its kind I had encountered at a ghost town cemetery, and I was grateful to those who had preserved the history and memories of these families. As I approached the headstones still visible through the snow, I noticed the surnames were as diverse as the town itself—Swedish, English, Chinese, German, Italian, and more. Some markers were so weathered by time that they were barely legible, while others, finely chiseled in marble, remained as sharp and clear as the day they were carved. The snowy hillside, gently sheltered by a stand of trees, offered a serene and fitting final resting place for those who had once lived in this forgotten town.

View of the homestead from the hill where Bonanza once sat

As I drove back down the hill, I caught sight of a few more buildings peeking through the trees—likely the last remnants of private structures in Bonanza still standing and functional. From there, I veered back onto the road and made my way toward the Yankee Fork Dredge. Within a few hundred yards, the massive silhouette of the dredge loomed into view. Its towering beams seemed to rise like spikes into the sky, and the windows of the control tower were dark and foreboding. Having read about dredges in an old horror novel, I couldn't help but feel a shiver, half-expecting a sinister face to stare back at me from one of those windows.

I ventured around the dredge along a snow-covered path, stopping to read the informational signs posted nearby. The buckets on the front conveyor were even larger than I had imagined, with steel walls more than three inches thick. They scooped up the earth, sending it into the dredge's "belly," where water was pumped in to sluice gold down through metal riffles—small ridges that allowed the heavier gold to settle while lighter materials washed away. It was hard to fathom that a machine so massive, more like a building than a piece of equipment, could move such a vast amount of stubborn earth.

Dredge with its bucketline to the left

The longer I wandered around the dredge, the more intrigued I became. Each window, level, and protrusion sparked visions of what the machine must have looked like when it was running—loud, clanking, and relentlessly chewing through the earth, rocks of all sizes tumbling violently through its chutes. I couldn't help but wonder how much the valley I had just passed through had changed over time, now mostly barren, with only a chaotic landscape of tailings and discarded boulders remaining on the valley floor. It was staggering to think that this colossal machine could run 24 hours a day, 365 days a year, with just three men. A winchman controlled most of the functions from above, while a bow oilman managed the diesel-electric units, and a stern oilman monitored the stacker that ejected the larger boulders behind the dredge.

Stacker protruding from the stern end of the dredge

Just behind the stacker, a striking orange vertical piece stands out. This houses the spud—a massive 55-foot tall, 17.5-ton cast iron post driven deep into the earth below the pond to serve as a pivot point. As the dredge moved back and forth, "eating" its way through the earth, the spud anchored the machine in place. The orange chute in front of the stacker is one of two sluice boxes at the dredge's rear corners. Inside these boxes are the riffles—metal ridges designed to trap the heavier gold as water washes through. The size of the riffles was so significant that they only needed cleaning every two weeks, a remarkably long interval compared to most wash plants or dredges, which required cleaning after just a week or less of operation.

The land surrounding the Yankee Fork Dredge had been mined since the 1870s. Initially, placer miners extracted the easier gold suspended in the river's silt. Later, lode miners arrived, attempting to access gold trapped in rock veins. According to George C. Stephens of the Idaho Geological Survey, traditional mining in the area lasted for about thirty years, well into the early 1900s. Afterward, most of the families moved out of the valley, and mining activity dwindled for the next three decades.

In 1932, state senator R. E. Whitten purchased several placer claims along the Yankee Fork and sold them to the Yankee Fork Placer Mining Company. The company introduced a small dredge to begin mining operations, but progress quickly stalled due to the large boulders and tightly packed gravel in the area. As the decade drew to a close, the Silas Mason Company began drilling test holes in the region, finding promising signs of gold. This led to the formation of the Snake River Mining Company, which brought in a massive dredge. The frame and floats were produced by Olsen City Manufacturing Company in Boise and trucked to the site. The rest of the machinery was produced by Bucyrus-Erie in Wisconsin and shipped by rail to Mackay before being placed on a truck to head up to the Yankee Fork.

Dredging operations officially began in August 1940 and continued for over two years until they were abruptly halted by the War Production Board during World War II, which deemed nonessential mining operations a lower priority. After the war, operations resumed in 1946 but once again came to a halt in 1947. The dredge, having yielded less gold than anticipated, was left idle. In 1950, the dredge and the surrounding claims were purchased by the Warren Mining Company, owned by Fred Baumhoff and J. R. Simplot, the founder of the multi-billion-dollar agricultural company of the same name. Confident there was still gold to be found, they set the dredge back into motion.

Part of the chain of 71 scooping buckets known as the bucketline, which could dig up to 37 feet below the water.

The Yankee Fork Dredge continued its relentless path northward until it reached a significant barrier: a massive bedrock formation just below the site of the once-thriving town of Bonanza. The powerful bucket line was unable to breach the solid rock, so engineers had to devise a solution. The only way to bypass the bedrock without disassembling the dredge was to float it. A dam was constructed to the south, allowing the dredge to be floated over the rock barrier and relocated to a more promising area. Once on the other side, richer ore was discovered, and the dredge continued to operate for another two years before the material was exhausted once again.

After sitting idle for more than a decade, the dredge was donated to the U.S. Forest Service by J.R. Simplot, with the intention of preserving it as a museum. Although it took years to secure the necessary funding, the effort eventually succeeded. By 1980, the Yankee Fork Gold Dredge Association had begun offering tours to the public.

Satisfied I had seen all I could of the dredge, it was time to continue on northward towards the ghost town of Custer a short distance up the road. Still fascinated by the mysteries hidden within the dredge’s rusted walls, I promised myself that one day, I would return in the summer to fully explore the secrets of this once-powerful machine.

Sources:

Stephens , George C. Idaho Geological Survey , 1991, A History of Gold Mining on the Yankee Fork River, Custer County, Idaho , https://www.idahogeology.org/pub/Reprints/R-11.pdf.

Walton, Aaron. “Bonanza Idaho.” Western Mining History, Western Mining History , westernmininghistory.com/towns/idaho/bonanza/. Accessed 7 Mar. 2025.

“Welcome to the Yankee Fork Gold Dredge .” Yankee Fork Gold Dredge, 26 May 2024, yankeeforkdredge.com/.