Scientists lowered Ontario lake pH for 17 years; trout still haven't recovered
A long-term scientific study in Ontario found that Lake 223, which was subjected to artificial acidification for 17 years, has failed to fully recover its trout population despite water chemistry returning to normal. The experiment highlights the lasting, multi-generational damage acid rain can inflict on freshwater ecosystems.
Why it matters
It demonstrates that environmental recovery is not always immediate or guaranteed even after the primary pollutant is removed.
A lake in northwestern Ontario became the setting for a landmark experiment on the effects of acid rain. For 17 years, scientists deliberately added sulfuric acid to Lake 223 every week, gradually changing the water's chemistry to mimic the effects of acid rain that was damaging lakes across North America and Europe. Between 1976 and 1993, the lake's pH fell from 6.8 to 5.2 as researchers watched how the changing conditions affected its ecosystem. The experiment ended decades ago, and the lake's water chemistry has since returned to conditions similar to those that existed before the experiment. But the ecosystem has not recovered at the same pace.
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