The algal bloom which lent Shuswap Lake a greenish hue over part of the summer has now completely dissipated according to the Shuswap Watershed Council (SWC).
The bloom, first observed in June, was easily visible in the water of the lake near Salmon Arm, Tappen, Canoe and Sunnybrae.
SWC program manager Erin Vieira said a few different SWC partner organizations were monitoring the bloom up until the end of September.
The City of Salmon Arm was monitoring the bloom from Canoe daily. Water samples taken by Interior Health and the First Nations Health Authority were analyzed for microcystin toxin, which can sometimes be associated with a blue-green cyanobacteria bloom.
The Columbia Shuswap Regional District (CSRD) and the provincial government were doing their own monitoring, analyzing water samples for algae species and density.
Vieira said the last of the monitoring results came in last week, and markers indicating how much plant life there is in the water have returned to normal. The water is also measurably clearer than it was earlier this year. Vieira added microcystin results have been negative for several weeks.
“Although the bloom was unsightly, at no point did monitoring indicate the water was unsafe for swimming or drinking for those with intakes on the lake,” Vieira said.
Possible causes for the bloom include heavy spring rains leading to high water levels in the Salmon River and nearby creeks, saturated soils adjacent to the river and a flush of nutrients from these soils into Salmon Arm Bay.
In the aftermath of the bloom, which experts called unprecedented in size, the watershed council is offering virtual presentations to community organizations this fall. It is hoped the presentations, which will also deal with other watershed impacts such as invasive species, will foster information sharing and good discussions of water quality and related issues. Groups interested in booking a presentation can email Vieira at email@example.com.