There isn’t just gold in them there mountains in California, there’s mercury too thanks to those hopeful miners looking to strike it rich. Back in the Gold Rush days of the mid-1800s, gold miners used mercury to separate gold from sediment. They sprayed it via large hoses onto the mountainside to wash the sediment downstream. A group of researchers from the University of California Santa Barbara recently found that this mercury is still a big problem for central California as heavy floods every ten years or so carry the mercury down from the Sierra Nevadas to the lowlands which ends up in the fish which humans consume. The researchers believe there is still enough mercury to continue the contamination for the next 10,000 years.