Gold Rush: Environmental Damage
The Gold Rush caused California to develop in many ways, but it also had a devastating impact on the environment. A large amount of lumber was needed to fuel boilers at the mines and to build the rapidly developing towns and cities springing up across the state. This demand led to large scale logging and contributed to deforestation. Mining requires water, so dams were built that changed the course of rivers. Hydraulic mining washed sediment into riverbeds and lakes, threatening agriculture development. Mercury was used in the gold mining processes, and this led to mercury contamination in water and fish that is still impacting California today.
California Gold Mining
This image is a reproduction of an original lettersheet published in 1855. The illustrations show the different methods and technologies used to mine gold, from the large flumes and dams to hydraulic mining. At the bottom is an illustration of a large quartz mill (stamp mill) powered by water. Quartz mills crushed the quartz rock and other ore, freeing the gold inside. Mercury would have been added to the mortar box during the grinding process to help improve gold recovery.
Map of Gold, Silver, and Quicksilver Regions
This reproduction of a map originally published in 1849, shows the gold, silver, and quicksilver mining regions in central California. Quicksilver (mercury) mining was done to obtain mercury for gold and silver mining. Mercury adheres to gold and silver making them easier to extract.
Quicksilver Mine Entrance
The photo from 1879, shows the entrance to a quicksilver (mercury) mine owned by the Great Western Quicksilver Mining Company. Mercury is extracted from cinnabar ore. The ore is ground up and heated to vaporize the mercury, then the vapor is condensed into liquid mercury. Traces of mercury remain in the waste rocks, and in the early days of mining, this waste rock was rarely disposed of properly, creating long term contamination.
Interior of Quicksilver Mine
Reproduction of a pencil drawing of the interior of Tunnel No. 2, owned by the Quicksilver Mining Company. Quicksilver (mercury) mining was a major industry in California and the first quicksilver mine was opened in 1846. Mercury produced in California also had a high trade value and was sold throughout the world.
Hydraulic Water Cannon
This image shows a hydraulic mining water cannon. Water cannons, such as this one, were used to wash away earth and mountains to access gold. In the early days of the gold rush, these cannons were small with canvas hoses, but more force was eventually needed. By the 1870s these cannons were anywhere from 13 to 18 feet long and could blast water 500 feet.
Hydraulic Mining of Mountainside
This image shows the environmental impacts of hydraulic mining on a mountainside. Several water cannons have blasted the mountain away. The loose gravel was washed into the flume and sluice boxes, where the heavier gold would settle. The rest of the dirt from the mountainside was directed into streams and rivers.
Old Hilltop Mine, Michigan Bar
This image shows the effects of hydraulic mining on a hillside at Michigan Bar in Sacramento County. Michigan Bar was a mining town originally founded in 1849. Hydraulic mining eventually destroyed the original site of the town.