The story of the Yuba Goldfields begins not with dredges but with water cannons. In the decades after the 1849 Gold Rush, mining companies moved from the valley floor into the Sierra Nevada foothills, where they blasted gravel hillsides with high-pressure jets of water in a process called hydraulic mining. The gold was captured in long wooden sluices, but the leftover sediment - called slickens - was simply dumped back into the mountain valleys. Rivers carried this flood of debris downstream. Between 326 million and 685 million cubic feet of mining waste poured into the Yuba River alone, raising the riverbed by as much as 100 feet in some places. Farms east of Marysville were buried under gravel and mud contaminated with mercury and arsenic, byproducts of the extraction process. Lawsuits by farmers finally curtailed hydraulic mining in 1883, but the damage was already done. The slickens stayed where the river had deposited them.

What the water cannons left behind, the dredges came to harvest. In 1893, the California Debris Commission began dredging the Yuba River near Marysville to mitigate the environmental wreckage, piling gravel along the banks. Then in 1904, W.B. Hammon saw opportunity in all that relocated earth and introduced the first bucket-line gold dredge to the area. These massive machines floated on their own ponds, scooping sediment from the river bottom with chains of steel buckets, running the material through onboard processing plants, and depositing the waste gravel in neat windrows behind them. By the end of 1904, two dredges were operating. By 1908, fourteen were working simultaneously, making the Hammonton field one of the most active in the state. The dredges operated for six decades, methodically turning the river valley inside out until the last one shut down in 1968.

The dredges did not simply extract gold. They rearranged the earth so completely that the very concept of land ownership became confused. Property boundaries that once followed the Yuba River became meaningless after the dredges shifted the river's course and replaced natural terrain with miles of gravel tailings. Legal disputes over title have plagued the goldfields for decades, with landowners, mining companies, and public agencies all claiming different parcels of a landscape that no longer matches any historical survey. The Goldfields remains the largest aggregate mine in California, and as recently as 1989 it was one of only two operating dredge gold-mining sites in North America. Access disputes have gone to court repeatedly, with a Yuba County judge ruling in 2000 that Hammonton Road through the fields is a public right-of-way.

Nature has its own plans for the Yuba Goldfields, and they are proceeding without human permission. The turquoise pools that fill the ravines between dredge tailings have become habitat for beavers and Northern river otters. Herons stalk the shallows. Bald eagles hunt from the cottonwoods that have colonized the gravel ridges. Wild turkeys pick through the underbrush, deer browse along the margins, and mountain lions have been spotted moving through the more remote sections. Ducks nest in the wetlands that formed where dredge ponds once floated industrial machinery. The goldfields demonstrate something ecologists have observed at damaged sites worldwide: given enough time and enough water, wildlife will move into almost any terrain, regardless of how thoroughly humans have rearranged it. The dredge tailings that were industrial waste a half-century ago are now functioning, if unusual, riparian habitat.

The Yuba Goldfields occupy an uncomfortable space between environmental catastrophe and accidental beauty. The turquoise color of the pools comes from mineral content in the exposed gravels, and in certain light the effect is striking enough to draw photographers and curious visitors despite the rough access roads. NASA's Earth Observatory has published satellite imagery of the site, and the television host Huell Howser visited in 2005 for his California's Golden Parks series. Yet the beauty is a byproduct of destruction. The mercury and arsenic that contaminated downstream farms during the hydraulic mining era remain in the sediment. The property disputes remain unresolved. The landscape, for all its strange allure, is a record of what happens when industrial extraction operates at full scale with minimal regulation. That the goldfields have become wildlife habitat does not redeem the damage. It simply means that the Yuba River valley, like all landscapes, keeps changing whether anyone approves of the direction or not.