Yuba Goldfields

Sediment deposits in Northern California

The Yuba Goldfields, also known as the Hammonton dredge field, is the largest gold dredge field in California. Located along the Yuba River approximately upstream of the town of Marysville, in Yuba County, the Hammonton dredge field was actively dredged for gold from 1904 to 1968. In total, more than of river sediment and lesser hydraulic mining debris was dredged to produce an estimated of gold. The goldfields are noted for their otherworldly appearance (a result of gold dredging operations), filled with roughly linear mounds of gravels (called dredge tailing windrows), ravines, streams and turquoise colored pools of water. From the air, the goldfields are said to resemble intestines. Wild turkeys, deer, ducks, Beavers, herons, bald eagles, Northern river otters and even mountain lions now live in the goldfields.

The first Yuba area miners panned for gold in stream beds in the valley, but within a decade large scale industrial processes replaced solitary prospectors. Mining companies moved from the valley floor into the Sierra Nevada foothills, where miners blasted gravel hillsides with high pressure jets of water—a process called hydraulic mining. After the miners extracted gold in long wooden sluices, they dumped the remaining sediment slurry back into the mountain valleys. Rivers and streams carried the flood of sediment—called slickens—down to the Sacramento Valley. Anywhere between to of debris was deposited in the Yuba River. The mine waste carried by the Yuba River ended up raising the riverbed (by up to 100 feet (30 m) in some cases), causing floods that buried farms east of the town of Marysville with gravel, mud, as well as mercury and arsenic (byproducts of the mining process). Lawsuits by farmers curtailed hydraulic mining in 1883, but the slickens remained behind in the river systems. In 1893, the California Debris Commission began to dredge the Yuba River near Marysville to mitigate the environmental damage from hydraulic mining, and piled the gravel along the river's banks. Later, in 1904, W. B. Hammon introduced the first bucket line gold dredge to the area, and before the end of 1904, two such gold dredges were operating. This Hammonton dredge field rapidly became one of the most active dredge fields in the state, with 14 gold dredges operating by 1908. The Goldfields is the largest aggregate mine in the State of California, as well as one of only two dredge gold mining operations in North America (as of 1989). The titles themselves are also under much dispute because mining has so shifted the landscape of gravel as well as the river itself that it has become unclear as to what the property boundaries are.