The use of salt on local roads is having a dramatic effect on the chloride levels of local waterways, according to the latest findings of the Friends of the Muskoka Watershed.
The group has been monitoring levels at 12 streams and waterways in the Gravenhurst area and their results are concerning.
In October of 2020 the Friends of the Muskoka Watershed published The Road Salt Threat to Muskoka Lakes, which revealed a correlation between chloride levels in some of Muskoka Lakes and their relative location with respect to major highways.
Their latest study was another step down the road toward understanding how road salt enters and moves through local waterways.
The group is collecting samples from the Gravenhurst sites roughly every three weeks and they have also installed a recording conductivity logger to measure conductivity every 15 seconds in the inflow stream to Jevin’s Lake just downstream of the big bend in Highway 11 at Gravenhurst. Jevin’s Lake has the highest chloride level of all lakes in Muskoka.
According to the Friends of the Muskoka Watershed:
“Conductivity Loggers provide ongoing measurements of the total dissolved solids (ions) in water, which lets us see how chloride levels rise and fall. Testing is in the early stages, but we are already seeing some interesting results.”
“The bar graph of conductivity measurements (above) made upstream (US) and downstream (DS) of Hwy 169, adjacent to the Muskoka Steamship and Discovery Centre, between December 6, 2021 and February 17, 2022. The upstream site includes general urban runoff from residential areas. The downstream site includes the addition of runoff from the highway showing an increase in conductivity by around 70%. By contrast, conductivity in a stream draining a nearby forested area (“Reference”) is approximately 10% of that form the urban and highway-affected areas.”
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