Cyanobacteria are photosynthetic bacteria that are naturally present in the earth’s fresh water and salt water ecosystems; they are not algae despite the fact that they are referred to as blue-green algae. For millions of years, these micro-organisms have been intimately associated with the development of life on the planet, since they helped enrich the earth’s atmosphere with oxygen. Through biosynthesis, they also produce several groups of substances including cyanotoxins. From an evolutionary viewpoint, cyanotoxins are believed to increase the competitive advantage of cyanobacteria, allowing them to dominate the aquatic environment in which they grow. The particular environmental problem created by cyanobacteria since the 1990s is the result of excessive proliferation in surface waters (ponds, lakes and streams), caused primarily by surpluses of nutrients such as nitrogen and especially phosphorus. In this context, drinking water facilities that are supplied with surface water could be vulnerable to cyanobacterial blooms, allowing whole cyanobacteria cells or their toxins to pass into the water distribution system.
Climate change is one of the factors that need to be considered in connection with the proliferation of toxic cyanobacteria1. However, there is little data on changes in the abundance of cyanobacteria in Québec, and more importantly, there is no summary of the removal capacity of Québec’s drinking water treatment plants. The purpose of this study was to review the state of knowledge regarding the elimination of cyanobacteria or their toxins during the production of drinking water in Québec.