Every summer, the same scene repeats itself on hundreds of North American lakes: greenish water, no-swimming signs, and worried residents.
Cyanobacteria, commonly known as blue-green algae, have become one of the most concerning issues for the health of our water bodies. Although naturally present, they can spread and bloom so much that they degrade water quality, disrupt recreational uses and, in some cases, produce toxins that are dangerous to human and animal health. They also reduce the oxygen available in water, creating dead zones that threaten fish and aquatic life.
But these blooms are more of a symptom than the problem themselves.
These blooms occur when several conditions combine: too many nutrients in the water, such as phosphorus and nitrogen, warmer temperatures and growing pressures on watersheds.
The Evolution of Cyanobacteria
A look at the numbers show the need to act is urgent.
Since the 1960s, cyanobacteria levels have increased in the majority of Canadian lakes at a rate seven times faster than before. In 2014, a major bloom led to a three-day ban on drinking tap water, affecting nearly 500,000 residents of Toledo, Ohio. The economic losses were estimated at 65 million dollars.
In the case of Lake Erie, associated costs could reach 5.3 billion dollars in Canada over the next 30 years. In Lac Saint-Charles, the City of Quebec’s main drinking water reservoir, the problem is becoming more visible: between 2020 and 2025, the lake experienced four times more days affected by algal blooms.
The solutions are often found upstream, in the way we manage agricultural land, urban runoff and healthy vegetation along on waterfronts.
This is where AquaAction's innovators come in.
Predicting before it's too late: WaterShed Monitoring
WaterShed Monitoring has developed Nerthus, an artificial intelligence solution that predicts conditions favourable to blooms one to three days in advance. By knowing when a water bloom is likely to occur, managers can activate their action plan before toxins reach swimmers or drinking water intakes. Rather than traditional solutions, this proactive approach prevents the exposure of humans and animals to cyanobacteria toxins.
Acting on nutrients at the source: FloteXa
By targeting excess nutrients and contaminants directly in water bodies, FloteXa's vegetated floating islands improve water quality, strengthen ecosystem resilience, and enhance riparian environments. From phosphorus and nitrogen to heavy metals, pesticides and hydrocarbons, FloteXa captures all sorts of contaminants.
Seeing what cannot be seen: EXO Tactik
EXO Tactik uses drones to map watersheds experiencing algae blooms. They then identify the risk areas and measure the thickness of sediment, which is a key factor in the release of phosphorus. All that data is then integrated into a geospatial platform that gives municipalities and managers a precise, spatial view of conditions that favour blooms, well before they occur.
Cleaning up what is already there: Biocene
When a bloom has already occurred, Biocene intervenes with non-invasive mechanical processes to directly remove excess algal biomass without disturbing the ecosystem. What sets its approach apart is that they turn the collected waste into something valuable, like bioplastics or fertilizers. An environmental waste becomes a resource: a circular approach complementary to prevention solutions.
Cutting propagation at the source: Ozero Solutions
Invasive aquatic species play an indirect but documented role in the spread of cyanobacteria. The zebra mussel, for example, filters micro-organisms present in the water but can leave behind certain cyanobacteria rather than consuming them. Ozero Solutions designs boat washing and decontamination stations installed at water access points, preventing the transport of these species from one body of water to another before they become established and difficult to control.
Monitoring, documenting, informing: Agiro
Managing cyanobacteria also relies on rigorous field knowledge. Agiro, a non-profit organization based in Quebec City with over forty years of experience protecting Lac and Rivière Saint-Charles, has developed a rigorous and reproducible bloom monitoring protocol: daily visual inspection, sample collection and real-time reporting. All of this data gives municipalities, watershed organizations and lake associations the information they need to intervene and ensure people can safely use the water.
Filtering nutrients where they enter: Capture Tech
Capture Tech restores water and soil systems by turning pollution and biomass residues into measurable ecological gains. Its deployable biofiltration tools enable communities to capture contaminants, track improvements, and convert recovered materials into circular soil-restoration products. The result is waste reduction and stronger watershed resilience.
Extracting phosphorus at the source: Lakewater Nutrient Capture
Lakewater Nutrient Capture (LWNC) has developed a barge-mounted mobile system that captures and attaches a recoverable value to the phosphorus taken directly in contaminated lakes. Using nano-iron oxyhydroxide filters, the technology eliminates harmful algae at the source and recovers the captured phosphorus as calcium phosphate, a usable agricultural product.
From Reaction to Action
Cyanobacteria are often the visible symptom of deeper imbalances in our aquatic environments. However, they are also a clear call to better protect our watersheds, invest in prevention and accelerate the adoption of concrete solutions.
The good news is that tools are increasingly available: better monitoring, more accessible data, entrepreneurial innovation, scientific expertise and local mobilization.
Together, these approaches allow us to move from a reactive to an anticipatory logic.
The challenges are real, but so are the solutions helping solve them.
Thank you to all of the AquaNation collaborators that helped write this story: Sonja Behmel, Stéphane Bouvier, Sarah Goubet, Christophe Langevin, Olivier Liberge, Karine Mailhot-Sarrasin, Carole Riopel, Manon Sayag, Kimia Shafighi, Matys Tessier, Maxime Wauthy