Malakoff Diggins State Historic Park in Nevada County was the site of one of the largest hydraulic mines in California . PHOTO BY CARLY CORNEJO
“( We ) can tell where the mercury is , and we can ensure that the sediment we remove is free of mercury and is actually just as good and can go out in your backyard garden ,” Jones says . NID ’ s project is helping establish best practices for other water purveyors .
In terms of how humans are exposed to mercury , contaminated fish is the main way this can happen . Mercury settled in dirt isn ’ t very dangerous — “ you can grow tomatoes in it ,” Martin says — but upon entering water , it gets into the bottom of the food chain and biomagnifies . “ So , 10,000 little sulfur-reducing bacteria get eaten by one bug , and that one bug gets eaten by a bigger bug , by bigger fish , and pretty soon you get to a … bass or a rainbow trout , there ’ s so much methylmercury in that fish ’ s body that it ’ s actually dangerous for humans to consume ,” Martin says . “ That ’ s the situation we ’ re in here in the gold country .”
On one side , Martin says , people argued that “ nobody in the Sierra fishes . Those are just a bunch of catch-andrelease Sierra Clubbers .” But between 2009 and 2016 , her organization surveyed 374 anglers at 14 mercuryimpaired water bodies and found that 43 percent planned to eat their catch and of those , 68 percent planned to also feed it to their families , says Alexandria Keeble-Toll , administrative director of The Sierra Fund .
In 2015 , the organization launched an annual volunteer Post It Day event to post fish consumption advisories . They have posted advisory flyers at more than 125 locations at 25 water bodies in five watersheds . Keeble-Toll says sharing information about safe fish consumption has become even more critical during the pandemic . “ We have noticed , and heard anecdotal reports from others working on this issue , that there has been an uptick in subsistence fishing since last March ( 2020 ). … As COVID has encouraged outdoor recreation as a safe diversion , there just seem to be more families interested in fishing .”
Besides eating fish , dust exposure to toxins is another concern . During the gold rush , gold may have been king , but miners also dug up silver , zinc , chromite , clay and stone , and brought up giant rocks loaded with naturally occurring lead , arsenic and asbestos that had been safely buried beneath the surface . Utilizing these materials for mining resulted in leftover waste later repurposed for things such as trail material , road base or rock base for play yards .
The Sierra Fund has tested trails on public lands built from abandoned mine materials — some had good systems and others were very dangerous . Martin gives the example of popular bike trails in Foresthill laden with asbestos fibers ; while walking on these trails doesn ’ t pose a significant
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