If you spend time at the lake, you very likely have seen Blue
Green Algae (Cyanobacteria). While it is a pretty turquoise
blue colour, it poses a serious health risk when present, and
unfortunately, it’s becoming more frequent. For example,
last fall a large bloom was seen choking the lake in Fort
Qu’Appelle, and in March people ice fishing on Pasqua and
Echo Lakes noticed the water in their ice holes was a blue /
purple colour, something never seen before.
So why is this happening? If you recall, in our previous articles, we learned that our lakes are green because of algae, that algal blooms are caused by excess phosphorus and nitrogen, and that we have a nutrient problem because we are sending too many nutrients into our lakes. While some cities are a major source of nutrients, surprisingly they are not the largest source. On average 91% of the phosphorus and 51% of the nitrogen is from non-point sources like agricultural runoff.
So given we have a nutrient problem it is no surprise our lakes have algae. But to make matters worse, blue-green algae is producing toxins, and when toxic blooms die and decay, those toxic chemicals can be released into the water. While most toxins are degraded within a couple weeks they can be in the water at low levels for many months after a bloom forms. Some blooms don’t contain toxins, but you can’t tell simply by how it looks. If you see a bloom, always take precautions and assume it is toxic.
According to the Water Security Agency the freeze and thawing cycles over the winter caused the Cyanobacteria outbreak from the fall to release a bright blue pigment called phycocyanin, as well as microcystin, a related toxin. While toxin levels were found to be well below the acceptable risk level for recreational activity and for the Canadian Treated Drinking Water Guidelines, citizens were advised to ensure pets do not drink the water. Dr. Leavitt with the University of Regina was quoted as saying “What we’re seeing is these blooms are becoming more toxic,” because of global warming and increased nutrient run-off (phosphorus and nitrogen) from farmers’ fields. Dr. Leavitt’s research using lake bottom core samples has confirmed that the lakes are much greener now than when Treaty 4 was signed in the late 1800s.
How can we prevent algae growth?
The best way to help prevent algae growth is good watershed management. By limiting and reducing nutrients that go in the lakes and by retaining and restoring
wetlands – we can do this. Storing water on the land in wetlands
prevents the nutrient rich farmland runoff from flowing
downstream into our lakes. Draining wetlands not only removes
these mini water treatment plants from the land, it also creates
more pathways for more nutrients and contaminants to flow off
the land and downstream. It’s simple, draining wetlands mean
more nutrients in our lakes and rivers, and that means more algae. Saskatchewan is the only Province without a Wetland Conservation Policy so having one would reduce nutrients and algae blooms.
Thanks to the research that Lower Qu’Appelle Watershed Stewards undertook, we now know where the nutrients are coming from so now it’s time for everyone to do their part and reduce the large amounts of nutrients that are getting into the Qu’Appelle River system. Reducing nutrient sources can make our lakes less green and less toxic to find out more and how you can help. Visit www.lqws.ca