page_title: Mercury contamination in California waterways
section_title: History of California mining
hierarchical_section_title: Mercury contamination in California waterways / History of California mining
caption_attribution_description: English: monitors breaking down sediment for mining.
context_page_description: Mercury contamination in California waterways posed a threat to both the environment and human health. The roots of the problem are in gold mining; since the California Gold Rush, mercury has been used for gold extraction. Historically, 10-30% of mercury was lost in the mining process, resulting in widespread contamination of river and lake sediments. Many water bodies in the state of California bear fish consumption advisories due to mercury content.
context_section_description: The California Gold Rush can be traced to James Marshall's January 24, 1848 discovery of gold on John Sutter's property. Marshall was building a saw mill right next to the river for Sutter, and the night before the iconic gold discovery Marshall diverted water from the American River through the lumber mill he was constructing tailrace to wash away loose gravel and dirt. The next morning (January 24, 1848) he discovered metallic flecks where the river water was flowing through the saw mill. He thought it was gold immediately, but didn't pursue it until the Sutter sawmill was completed.
  By the time of the following spring Marshall's gold discovery, the largest gold rush in American history began. In this short year the non-Native American population raised from 14,000 to 100,000. The population increased again to 250,000 by the year of 1892.
  Gold was easily extracted from the rivers, by scooping and silling the river soil and gravel. The bottom trawler method was also developed to extract more gold at once. This was the pulling of metal baskets and rakes across the river beds to stir up gold, and scoop out gravel that was rich in gold. It was later, when the gold in the river bed wasn't as plentiful, that new mining techniques were being developed to extract gold more efficiently from the ground. One of the main, and also most destructive methods was that of hydraulic mining. This involved the redirecting of water from the river into a narrow channel, into a large canvas hose, and iron nozzle. Then these water canons which were called monitors it would shoot a very high pressure stream that would break apart hillsides. The water, slurry, and debris, mostly gravel would flow over large sluices and drainage tunnels. This was also when mercury was beginning to be used to help extract the gold from the masses of ore and silt.
caption: Monitors (water canons) in the placer mines used to break down sediment for gold exposure.
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