This method used high-pressure jets or cannons to shoot a powerful stream of water to dislodge rock material and remove trees , rocks , turf and dirt , anything that stood in the way of the gold ; the soil , sand and gravel washed down a series of sluices , which caught the heavier materials that contained the gold ( the muddy waste tailings were washed into waterways ). Hydraulic mining required lots of water . Trees were cut down , rivers dammed , streams and creeks rerouted to mining sites to feed the hydraulic-mining beast . This method was “ incredibly disturbing to the landscape ,” Martin says .
Hydraulic gold mining also required mercury , then commonly known as quicksilver , and there was plenty of it to be found not too far away , because before the discovery of gold came another important discovery : mercury mines in the Santa Cruz Mountains . California ’ s Coast Ranges had massive deposits of the heavy metal , an area the U . S . Geological Survey describes as “ among the most productive mercury districts in the world .”
Mercury was used in the separation of gold from rock : Gold dissolves in mercury , and then the solution is boiled , vaporizing the mercury and leaving the gold behind . Mercury was especially prevalent with hydraulic mining . According to the USGS , “ Mercury was used to enhance gold recovery in all the various types of mining operations ; historical records indicate that more mercury was used and lost at hydraulic mines than at other types of mines .” Court injunctions began restricting hydraulic mining in 1884 , with North Bloomfield Gravel Mining Company at the center of lawsuits against excessive debris and damage to farmland . ( The site of North Bloomfield ’ s largest mine , Malakoff Diggins , is now a state historic park .)
By 1852 , the gold rush had peaked , although mining continued . These operations had become highly industrialized , the majority of individual miners lived in squatter conditions and failed to strike it rich , and the price of gold had dropped significantly . “ When the price of gold , which had been fixed by our government at a very low level , was just too low , the miners basically walked away from their haul without doing anything to reclaim them , leaving behind these mines-scarred lands ,” Martin says . In addition to the physical hazards of old mines , contaminants like mercury seep out of these sites and wash down hillsides and in waterways .
The dangers of mercury exposure weren ’ t really understood until a century after the gold rush , when in 1956 , a 5-year-old girl in Minamata , a coastal city in Japan , had trouble walking and speaking and suffered convulsions . This girl became the first official case of Minamata disease , a neurological syndrome caused by severe mercury poisoning .
The Chisso Corporation ’ s chemical factory had been releasing methylmercury in its industrial wastewater , which emptied into Minamata Bay . The discharged toxin accumulated in the fish and shellfish consumed by villagers . The poisoning affected children most , but fetuses exposed in utero had horrific birth defects . “ I remember seeing pictures as a child and believing that they were victims of the nuclear bomb in Hiroshima ,” Martin says of the sick children . Mercury is now understood to be one of the most toxic metals found in the environment and linked to “ toxic ef-
May 2021 | comstocksmag . com 35