Hydraulic mining was a large-scale form of placer mining. Placer mining, or surface mining, was the earliest form of gold mining in the foothills of the Sierra Nevada Mountains in northern California.
Placer mining generally entailed searching for gold in the top layer of soil, usually in streambeds. The classic image of the old prospector squatting next to a stream, swirling dirt and gravel around in a large pan to separate the gold from the soil, is the simplest form of placer mining.
Miners quickly discovered that the more earth they could process, the more gold they were likely to find. Instead of working with one pan of soil at a time, they built sluice boxes, long toms, and rockers that could handle several shovelfuls continuously.
The sluice box was a simple wooden box with a sloping bottom and two sides. Narrow slats were placed across the bottom, making ridges down the length of the sluice.
Dirt and gravel were shoveled into the upper end of the sluice. Water was channeled through, washing the material down the sluice and over the ridges. The relatively heavy gold flakes would settle behind the ridges while the dirt washed away. The miner could then collect his meager earnings and start the process again.
Innovations rapidly followed as miners collaborated to find ways to process larger quantities of earth more rapidly. Hydraulic mining became the largest-scale, and most devastating, form of placer mining.
Water was redirected into an ever-narrowing channel, through a large canvas hose, and out a giant iron nozzle, or monitor. The extremely high pressure stream was used to wash entire hillsides through enormous sluices.
While generating millions of dollars in tax revenues for the state, the other side of the double-edged sword of hydraulic mining was its devastating effect on the California eco-structure. While mountains were being washed away, millions of tons of earth and water were being run off into the high mountain streams that fed the rivers which flowed down into the valley.
The rapid flow of the rivers down the western slopes of the mountains allowed the earthen material to remain suspended in the water. However, once the rivers reached the valley floor, the water slowed, the rivers widened, and the sediment settled into the riverbeds. As the riverbeds were raised by the ever-increasing sediment, the water would naturally seek out new channels and frequently overflowed the river banks, causing major flooding, especially during the periods of Spring runoff.
Cities and towns in the Sacramento Valley were continually wary of devastating floods, while the rising riverbeds made navigation on the rivers increasingly difficult.
Perhaps no other city experienced the boon and the bane of gold mining, as did Marysville. Situated at the confluence of the Yuba and Feather rivers, Marysville was the final "jumping off" point for miners heading to the foothills seeking their fortune. Steamboats from San Francisco, carrying miners and supplies, navigated up the Sacramento River, then the Feather River to Marysville where they would unload their passengers and cargo.
Marysville, named after a surviving member of the ill-fated Donner Party, quickly grew into a major supply center for the mines and the third-largest city in California, behind San Francisco and Sacramento. Mule trains continually carried food staples, tools, and building materials up into the foothills and a booming service industry erupted.
The city also became a small manufacturing center for many of the tools needed by the miners, including, eventually, the giant iron monitors used by the hydraulic mining companies.
Because of its location on two rivers, Marysville had frequent problems with flooding and eventually constructed a complex levee system to keep the rivers in their banks and out of the city. Hydraulic mining greatly excerbated the problem of flooding in Marysville. It also made the waters of the Feather River shallow enough that most steamboats could no longer navigate all the way to the Marysville docks.
By the early 1850's, while hydraulic mining was at its height, small-scale placer mining was a thing of the past. The vast majority of lone prospectors could not sustain themselves, and the mining industry was taken over by large companies, most of which found hard rock gold mining (or quartz mining) more profitable.
California settlers soon discovered what Mexican "Californios" had known for years, that the real gold was the valley's fertile soil, and agriculture quickly became the state's predominant industry, as it still is today.
By the latter part of the century, while the city remained reasonably protected from flooding by the levees, the same was not true for the surrounding farmlands. Frequently devastated by flood waters, farmers demanded an end to hydraulic mining. In the most renown legal fight of farmers against miners, one farmer sued the largest hydraulic mining operation and the landmark case of Edwards Woodruff v. North Bloomfield Gravel Mining Company made its way to the United States Supreme Court. In 1884, the court proclaimed hydraulic mining to be “a public and private nuisance” and decided in favor of the plaintiff.
North Bloomfield, and the several other hydraulic mining companies, soon folded, leaving a permanent legacy of scarred landscapes, sediment dams, and innavigable waterways.
