In 1997, California officials poisoned Lake Davis to kill invasive northern pike; the fish returned within two years

In October 1997, California wildlife officials dumped enough fish poison into a Sierra Nevada reservoir to kill every living fish in it, all in an effort to wipe out a single invasive species. According to the U.S. Environmental Protection Agency (EPA), California wildlife officials treated the entire Lake Davis reservoir with rotenone in October 1997 to eradicate invasive northern pike. The operation appeared to work initially. Within about two years, the fish it was designed to eliminate was back.

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