What’s in Our Water: Concentrations of Toxins at 1,921 meters

Last summer two environmental scientists arrived in Mount Revelstoke National Park to test four alpine lakes for DDT levels.

DDT (dichlorodiphenyltrichloroethane) is synthetic chemical pesticide that was heavily used in the mid 1900s for agriculture. The 1962 publication of Rachel Carson’s book Silent Spring generated controversy over the impacts of DDT on the environment, particularly wildlife and birds.

Locally, scientists are interested in how this persistent chemical can impact our water, particularly fish. Fish living in high alpine lakes tend to grow slower, and can live longer than those inhabiting lower elevation lakes and rivers. At higher elevations, trout can live up to 20 years, allowing more time for toxins to accumulate in their bodies.

Though now banned in Canada and the US, DDT is still used today in Asia. Scientists arriving at Eva Lake, one of the four lakes studied last summer, were hoping to find out whether the DDT concentrations in trout in Mount Revelstoke National Park were a result of the historical uses of the chemical, or current uses across the Pacific Ocean.

Fish that had been tested were found to have 16 times higher concentrations of DDT than Health Canada consumption safety guidelines report. There is now a catch and release only policy in place for these high altitude lakes.

How do chemical pesticides threaten a relatively pristine lake, like those protected by our National Park system? Just how far can these chemicals travel, and how long do they remain in our environment?

Healthy Rivers, Living Lakes is this year’s theme for Canada Water Week.

Healthy Rivers and Living Lakes require a balance of nutrients, oxygen, organic material, and natural chemical compounds to sustain life. High concentrations of toxins such as DDT can upset this balance.

Living Lakes Network Canada facilitates collaboration in education, monitoring, rehabilitation and policy development initiatives for the long-term protection of Canada’s lakes, wetlands and watersheds. Our vision is for watersheds that provide life support systems that ensure they remain balanced and healthy for future generations.




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