Large investments have been made to clean up acid drainage into streams and rivers polluted by toxic metals from abandoned mining sites. A new study published in Freshwater Science based on long-term monitoring data from four U.S. Environmental Protection Agency Superfund sites in California, Colorado, Idaho and Montana shows that cleanup efforts can allow affected streams to recover to near natural conditions within 10 to 15 years after abatement work begins.

David Herbst, a research scientist at UC Santa Cruz and co-author of the paper, says, “The good news from them all is that Superfund investments can restore the water quality and ecological health of the streams.” Researchers combined data from long-term monitoring during periods of 20 years or more using aquatic insects and other diverse invertebrate life such as flatworms and snails as indicators of the restoration of ecological health, with nearby unpolluted streams as standards for comparison. Much of the recovery occurred within the first few years of treatment. Herbst says that the promising results suggest that even daunting environmental problems can be remedied.