Habitation - Trucs et conseils - Algues bleues : des pistes claires pour les eaux troubles

Blue-green algae have been around for some 3 billion years, and for most of that time they haven’t caused any problems. But in recent years these tiny organisms – whose scientific name is cyanobacteria –, which are the basis of the food chain in aquatic ecosystems, have surfaced (pun intended) in many of our lakes, giving waterfront residents the blues (pun again intended) and prompting many Quebec municipalities to express serious concern about their proliferation. It is possible to take action to curtail the phenomenon, and there is a pressing need to do so. This article paints a portrait of a crucial battle for the survival of our lakes and rivers.

A blue-green bloom
Cyanobacteria are usually invisible to the naked eye, but when they proliferate rapidly, they form a green or turquoise mass on the surface of a body of water, called a bloom. A cyanobacterial bloom looks something like spilled paint or pureed vegetables. Sometimes a slimy, foul-smelling layer of scum forms on the shore of the lake.

Our aging waterways: A fertile medium for proliferation
Cyanobacterial blooms form when a lake contains too much nitrogen or phosphorus. And because they thrive in calm, shallow, warm water, they proliferate very quickly in eutrophied – i.e., aging – bodies of water. At the end of their life cycles, some types of cyanobacteria release toxins into the water that are potentially dangerous to the health of humans and animals.

The risks to your health
Exposure to or ingestion of water contaminated by cyanobacteria poses risks to your health and that of your pets. If swallowed, contaminated water may result in abdominal distress, headaches and fever, while direct contact may cause irritations of the skin, eyes and nose, as well as a sore throat.

A fragile equilibrium destabilized by human activity
Phosphorus is a chemical element that is essential to life, and which nature wisely produces in small quantities. Human actions, however, upset this fragile balance by releasing large amounts of phosphorus into natural habitats. There are many culprits, from multiple sources:

  • Forestry operations, baring of soils, and environmental destabilization;
  • Farming operations, spreading of fertilizers;
  • Depletion of “riparian buffer strips”;
  • Aging septic systems, poor control of wastewater effluents;
  • Use of detergents and cleaning products with strong phosphate concentrations.

All of these harmful actions, repeated every day, are endangering our waterways.

Lakeside and riverside residents on the front lines
Research has shown that on average, every human living within 100 metres of a lake is responsible for producing as much phosphorus as is released naturally by one hectare of forest. Clearly, there is a pressing need for these residents to take to the front lines of any counter-attack. But where do we start?

  • Organize waterfront property owners – Creating an association of waterfront property owners is a great way to raise people’s awareness of the problem and incite them to work together to safeguard a lake and its shorelines.
  • Let nature reclaim shorelines – Stop mowing grass, clearing brush and spreading fertilizer within a 10- to 15-metre wide band (called a riparian buffer strip) around the lake.
  • Re-establish natural vegetation – Help regenerate shorelines by sowing herbaceous plants specially designed for shoreline re-naturalization or stabilization, and planting shrubs that are suited to riparian zones. Their roots will stabilize the soil, filter out pollutants and retain nutrients that will otherwise flow into waterways. Also, the shade that they create helps keep the water from heating up, which contributes to algae proliferation.
  • Check your septic system and pump it out – Make sure your septic tank meets standards. Maintain it and pump it out in compliance with provincial regulations (must be pumped out every two years if you are a permanent resident, and every four years if you are a seasonal resident). Toilets or showers that back up or that take an abnormally long time to drain are signs of a defective system. Outside, symptoms include ground that is continually soggy or spongy, a noticeable sewage odour after it rains, or fecal coliform bacteria (E. coli) detected in a nearly well or ditch.

    Better control of wastewater discharge will reduce the amount of phosphorus that reaches the groundwater and, in turn, flows into aquatic environment.
  • Don’t use high-powered motorized watercraft – Their wakes cause shoreline erosion, and the churning of the water by their powerful engines frees up phosphorus that has accumulated in large quantities in the sediment at the bottom of the lake.
  • Practise lawn-care techniques that respect the aquatic environment – Do not spread fertilizer within the riparian buffer strip, and stop using pesticides. For more details, see the website of the Coalition for Alternatives to Pesticides and click on “lawns.”
  • Use organic or phosphate-free detergents and cleaning products – This is a must for everyone, especially waterfront residents. Organic, phosphate-free clothing and dishwater detergents that can replace the products you might normally use are now available. The CAA-Quebec website includes a detailed list of “green” cleaning products for the home. And in March 2008, Protégez-vous magazine published the results of a study of certain phosphate-free detergents, along with a list of detergents that shows their respective phosphorus concentrations.

What to do if you suspect a problem with blue-green algae?

  • First, make sure it actually is a cyanobacterial bloom – There is another aquatic phenomenon, which carries no health risks, that can easily be mistaken for algae caused by cyanobacteria. The Quebec Ministry of Sustainable Development, Environment and Parks (MDDEP) has produced an identification guide that will help you be sure your suspicions are correct.
  • If you have checked and are sure – You must immediately notify the authorities of the situation. During regular business hours, contact your regional MDDEP office and ask for the person in charge of the blue-green algae file. Outside regular hours, contact Urgence-Environnement at 1 866 694-5454.
  • Stop using the water – Don’t drink the water, make ice cubes with it or use it to wash or prepare food. Boiling contaminated water will not eliminate the toxins.
  • Avoid all direct contact – Don’t swim in contaminated water, and stop any recreational or other activity on the water that might cause accidental ingestion.
  • Don’t eat any fish or aquatic plants from the contaminated waterway.
  • Don’t pour an algicide into the lake water – An algicide will kill the cyanobacteria cells, which is what releases the dangerous toxins.

Public notices: The Quebec government’s new position
As of 2008, in order to avoid unduly alarming the public, the Quebec government will no longer automatically issue a warning every time cyanobacteria are detected in a body of water. Notices will be limited to publication by the MDDEP of the list of bodies of water affected by a ban on swimming or water consumption.

Other sources of information
Quebec Portal www.gouv.qc.ca

Quebec Services:
Quebec City region 418 644-4545
Montreal region 514 644-4545
Elsewhere in Quebec 1 877 644-4545 (toll-free)