Getting to know blue-green algae
By Sue Tiffin
Published Oct. 23, 2018
Though cyanobacteria have been around for over 2.5 billion years, we’re still learning about how best to deal with accumulations of the photosynthetic bacteria, groupings known as blue-green algae blooms.
Richard Ovcharovich, manager of environmental health for the HKPR District Health Unit, presented about blooms, a seasonal phenomenon, at the board of health meeting on Oct. 18.
Cyanobacteria occur in freshwater, marine environments, Antarctic lakes, hot springs and in damp soil around the world, including in Haliburton County.
The blue-green algae is not actually algae, but rather photosynthetic bacteria that can be found throughout the water column, and can in favourable conditions – a lot of sunlight, warm temperatures, no wind, calm water – pose a threat to human safety.
Blooms can cause reduced water clarity, loss of deep water oxygen, a foul taste, a strong odour of either newly mowed grass or rotting garbage and may produce toxins.
“As the conditions improve for their survival, they’ll start proliferating,” said Ovcharovich.
As water becomes cloudy, it’s necessary to take precautions when swimming, as clarity becomes an issue. At this stage of a bloom, considered category one, drinking precautions don’t generally need to be taken, but anyone using water from lakes, rivers or shoreline wells needs to have a proper water treatment system, or in fact a treatment train, in place: filtration, disinfection and some type of polishing device or polishing film.
Category two brings greater concern.
“This is where the water kind of turns pea-soup green,” said Ovcharovich.
It’s not recommended for people to swim in affected water, because it’s difficult to see anyone under the water, and also some individuals might have symptoms if toxins are present. Symptoms of exposure to toxins might include headache, fever, diarrhea, abdominal pain, nausea, vomiting, itchy, irritated eyes and mild rash.
“When this happens, it’s recommended they don’t use the water,” said Ovcharovich
As cells begin to die off, a category three bloom is created.
“As they die, and float to the top, they create this crust of scum over top,” he said. “Sometimes it looks like paint spilled all over the top of the water column.”
Fish caught from the area of an algae bloom are not recommended to be consumed, especially their internal organs.
At this point, surface water should always be treated for bacteria and parasites, and water should not be used for drinking, cooking, rinsing fruits or vegetables or washing dishes, and should not be deemed safe if boiled – instead this process evaporates the water, stabilizes the toxin and can actually concentrate it. Dissolved cyanobacteria toxin may affect shoreline wells. Municipal drinking water, however, can be consumed.
Blooms should be reported to the Ministry of Environment, Conservation and Parks, which recommends sending photos along to quicken the assessment and identification.
The agency will confirm, after initial notification, whether or not blue-green algae is present. If so, samples are collected and sent to a lab – but lab identification can take up to three days, while toxicology results can take up to five days – days in which the public might be exposed, or the bloom might relocate or dissipate. Because of this lag time, Ovcharovich said visual observation can be most beneficial.
Factors contributing to cyanobacterial blooms include storm water runoff, over fertilized and manicured lawns, malfunctioning or faulty septic systems, and accumulation of organic materials from aquatic and land plants.
Education and awareness campaigns in Haliburton County have urged lakefront property owners to help by using phosphate free detergents, maintaining naturally vegetated buffer strips along shorelines, and ensuring that septic systems are in good working order.
Ovcharovich noted in his presentation that more research is required to determine the effectiveness of private water treatment systems, understand toxin residual in the area after a bloom is gone and determine the size of a bloom that is of concern.
“We got into a situation back in 2011, when we had the big bloom in Sturgeon Lake,” he said. “We identified it, and issued a water use advisory, because the bloom was present, and then the rescinding of that advisory was very difficult to do. Because the bloom pops up in one area, dissipates from that area, and you don’t know where it’s going to pop up again.
“That had a significant effect on the recreational industry in the City of Kawartha Lakes. It scared a lot of people and it wasn’t as worth it as we thought it would be. At that time we were trying to do the right thing and protect everybody from everything, and in retrospect we learned that there were better ways to do this. It’s got to be a practical approach to protecting public health.”
The public can report potential bloom occurrences to the MECP Spills Action Centre at 1-866-663-8477. Further information can be found at www.hkpr.on.ca.