Gold Rush Legacy

Environmental impacts, 150 years later

• Hannah Schardt
• Apr 01, 2006

THE MID-19TH CENTURY California Gold Rush extracted more than 700 tons of gold from the hills of the Golden State. Unfortunately, it also pumped 10 times that much mercury--used to separate gold from surrounding rubble--into the state's lakes and rivers. Over the next several decades, much of that mercury made its way into the San Francisco Bay, where it persists today. A new study indicates that it could take decades for the bay to rid itself of that mercury--and that's under the best possible circumstances. Researchers at the state's Lawrence Berkeley Laboratory, using a novel method of modeling the bay's mercury content, found that even if no more of the heavy metal enters the bay, the level of mercury in San Francisco Bay fish will remain dangerously high for human consumption for another half century.

Researcher Tom McKone says that the persistence of the mercury should teach us a lesson: Consider the consequences of what we introduce into nature. "What these people did in 1850--their failure to think about the implications of using all this mercury--we're still paying for today," says McKone. "Then you think about all the [chemicals] we're putting out now. What if we suddenly find that we don't want those out there in the environment either?"