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The Problem With Blue-Green Algae

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At Lac Gauvreau, sightings of blue-green algae blooms were first reported in 2000, and almost every year since then, indicating the presence of high nutrient levels in the lake water. (See photos below)

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Blue-Green Algae: A concern for Lac Gauvreau residents
In 2020-21, Enviro Lac Gauvreau received several grants through the La Pêche Municipality Green Fund to mitigate the lake’s high nutrient level through measures such as shoreline restoration.

According to the Lac Gauvreau News - August 2010, Published by the Gauvreau Lake Environmental Protection Association, “Phosphate levels in the Lake remain elevated, a state which continues to foster the possibility of the appearance of algae.”

The Lac Gauvreau News - June 2009 wrote this warning: “Lac Gauvreau Still At Risk!… The appearance of an algal bloom (cyanobacteria or blue-green algae) early last November confirms that our lake remains vulnerable to this kind of pollution [caused by nutrients such as phosphorous].”

High nutrient and algae levels have been of great concern for years. This story in The Low Down to Hull and Back News, June 18 - 24, 2008 reminded readers of this fact: “The health of the lake [Gauvreau] was called into question in 2000, when a blue-green algae bloom devastated cottagers by causing the [temporary] closure of the lake… After 2000, with the help of the mayor, the lake’s volunteer environmental group put together an action plan to clean up the lake…”

    kayaking Blue-Green Algae
    Blue-Green Algae (Cyanobacteria) and their Toxins
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    As far back as 2000, a blue-green algae bloom (a familiar name for a class of bacteria called cyanobacteria) devastated cottagers by causing the temporary closure of Lac Gauvreau. After 2000, with the help of the mayor, the lake’s volunteer environmental group put together an action plan to clean up the lake. We learned that cyanobacteria are naturally occurring, and lodge in the sediment on the muddy lake bottom. The bacteria are generally fed by nutrients in the water. The right combination of temperature, light and calm water can cause the bacteria to bloom into a blue-green scum on the lake surface. The result is very unpleasant and can produce toxins that are harmful; all use of the water in the area of a bloom should be avoided.

    Despite continued efforts, localized blue-green algae blooms have appeared virtually every year, indicating the continued presence of high nutrient levels. Measures to minimize this occurrence have been concentrated on preventing more nutrients from entering the lake (restriction on fertilizers, shoreline restoration and phosphate-free cleaning materials). Since the wake from motorboats stirs up the sediment in shallow areas—thus freeing the bacteria to rise to the surface—our Guidelines For Responsible Boating will help reduce blooms.

    Click on the tabs below to learn more…

    What are cyanobacteria?

    Cyanobacteria form in shallow, warm, slow-moving or still water. They are made up of cells, which can house poisons called cyanobacterial toxins.

    What are cyanobacterial toxins?

    Cyanobacterial toxins are the naturally produced poisons stored in the cells of certain species of cyanobacteria. These toxins are usually released into water when the cells rupture or die.

    Does the presence of a cyanobacterial bloom always mean the water is contaminated?

    No. Researchers generally agree that between 30 and 50 per cent of cyanobacterial blooms are harmless because they contain only non-toxic species of freshwater cyanobacteria. Because there's no obvious way to tell if a particular bloom is toxic, samples have to be analysed in a laboratory before a body of water can be declared safe.

    How will I know if I've accidentally come into contact with cyanobacterial toxins?

    If you ingest water, fish or blue-green algal products containing elevated levels of toxins, you may experience headaches, fever, diarrhea, abdominal pain, nausea and vomiting. If you swim in contaminated water, you may get itchy and irritated eyes and skin, as well as other hay fever-like allergic reactions. If you suspect you might have come into contact with cyanobacterial toxins and are experiencing any of these symptoms, rinse any scum off your body and consult your physician immediately.

    Can water containing cyanobacterial blooms be used for recreational activities?

    Blooms in recreational bodies of water are usually associated with unpleasant odours and offensive appearance on shorelines as the scum accumulates and decays. Individuals should avoid swimming and other water-related activities in areas with dense blooms.

    What should I do if I suspect water has been contaminated by toxic cyanobacteria?

    Because all cyanobacterial blooms are potentially toxic, it's always best to stay away from contaminated areas. If you see a blue-green algae bloom in Lac Gauvreau, please contact Enviro Lac Gauvreau immediately at to report the sighting.
    pool What can we do?
    What you can do to prevent blue-green algae blooms?
    Do let tall grass and bushes grow along the shoreline; keep your land well treed; replant indigenous bushes and trees.
    Don’t mow the lawn right to the water’s edge, but leave a buffer zone of at least 3-5 metres.
    Do use phosphate free products for cleaning and washing.
    Do have your septic tank emptied every two-three years.
    Do go slowly. Take care that the wake from your motorboat does not cause shoreline erosion or stir up sediments in the shallow parts of the lake.
    Don’t bathe or shampoo or use any soap directly in the lake.
    Do seek authority from the Municipality for all clearing, excavating and filling work within the 15m shoreline setback from the lake
    Do put this list on your fridge door to alert your visitors or renters too.
    cabin Blue-green algae & home value
    Impact of blue-green algae on home value
    The worst lakes in Quebec: financial nightmares near lakes in poor condition
    Better to find out about the quality of the water before spending a fortune on a cottage

    Journal de Montréal
    2 July 2022

    Owners have seen their residence lose up to 25% of its value because it is located around a lake in very poor health.

    No swimming, hard-to-sell residences, court battles, loss of revenue for cities; blue-green algae (cyanobacteria) or invasive alien plants like Eurasian watermilfoil not only poison water quality. They also poison the lives of local residents.

    For the time being, the pandemic has caused a spike in cottage prices. But some may have bad surprises in a few years.

    > Read Google translation

    > Lire l'article original en français dans le Journal de Montréal

    Whether or not blue-green algae affects lakefront properties is controversial.
    According to an article published April 18, 2021 on the website Water Today, S. Blais and Associates Inc., Home Evaluators in the Outaouais region, believe that the detection of blue-green algae is not yet an issue that waterfront cottage owners in the area need to worry about. However, if the problem were to get worse, it could have major impacts on the eventual sales of the affected properties, they explain.

    “In our private expertise for the Outaouais region, we do not consider the blue algae problems in the evaluation of properties ... Not at this time because the problem is too young to see a pattern emerge. However, if a massive and recurring proliferation settles, we may see a major impact in the eventual sale prices of waterfront properties to polluted water bodies by blue-green algae. Everything is played with us in a matter of PERCEPTION. Indeed, for the problem to have an impact, it must be persistent, real and perceived...”

    Stéphane Godard, Real Estate Broker for MULTI-IMMO LAURENTIDES Real Estate Agency, in the Mont-Tremblant region, has a different point of view: "Blue-green algae in a lake dramatically affects the value of the home. Exactly how dramatically it affects the value of course depends on the history of the lake, how many times it has happened and the treatment of it.”

    “If it only happened once, several years ago, it may not affect the price of homes on that lake, but if it was only a couple years ago, for example, it would still impact the price of the home.”

    “Of course, if the lake has a recurring problem with blue-green algae this will dramatically affect what they can sell their home for and even the likelihood of people being interested in their property whatsoever.”
    >Read the article
    water Parent Creek projects
    Characterization and revitalization project of Parent Creek, 2008
    Aware of the necessity of action for the protection of the water resource and aquatic habitats, the Gauvreau Lake Environmental Protection Association (GLEPA) decided to establish a drainage basin enhancement plan, starting with its main affluent.

    The dredging of the Parent creek in the 1960s resulted in the disappearance of habitat diversity. The Association thought that it was possible to implement corrective measures to revitalize the creek, increasing the quality of fish habitats and their productivity. The aquatic habitats of the creek were not known at the time. Acquiring this knowledge was an essential first step in establishing priorities for its revitalization.

    The following were the specific objectives of the project:
    • Characterize the aquatic habitats of Parent and Gibson Creeks (18 Km),
    • Characterize the conditions of the creeks shorelines and erosive areas,
    • Establish a five-year plan for the revitalization of aquatic ecosystems.
    Several studies had already established the Parent Creek as the main source of nutrients, such as phosphorus and nitrogen, which favour the anarchic growth of plants, algae and cyanobacteria in the lake. The expected by-product of the creek revitalization project was the substantial reduction of nutrients inflow to the lake and the slowing of its aging process.

    The GLEPA mandated a private consultant’s firm to conduct the characterization of the Parent creek. Read more and see the report below.

    Due to a GLEPA initiative, the environmental consulting firm PRO FAUNE published a ‘Development Plan for the Aquatic Habitats and the Banks of Parent Creek’. This study report identified a number of concerns that affect the quality of the aquatic habitats of the creek – and as a consequence, the water quality of Lac Gauvreau – including the condition of the creek banks along the farm fields, the electric fencing, and the access by cattle for drinking water.

    Information already available was combined with data collected on the ground in September 2007, allowing an evaluation of the problems of Parent Creek and the formulation of recommendations for the development of the potential for fauna and of water quality. With this information, the Association and its local and governmental partners were able to compose a plan for intervention and protection of the sensitive habitats for fauna and the creek banks in order to preserve the biodiversity of the principal inflow to Lac Gauvreau.

    In summary, to improve the quality of the Parent Creek ecosystem and to optimize its potential for fauna, the report deemed it essential to keep livestock at a distance from the Creek, to establish adequate watering sites, to stabilize the creek bed and banks, and to ensure the effectiveness of individual septic systems of residences in the drainage basin in order to reduce the runoff of suspended material, total phosphorus and fecal coliform.

    > Read the Parent Creek revitalization study; key findings published June 28, 2008

    > Read the full report: 2008 Bolduc Ruisseau Parent

    > Read the Executive Summary Parent Report

    > Read article in Gauvreau Lake News, June, 2008

    In 2007, Lac Gauvreau received $14,000 to study the impact of pollutants flowing into Lac Gauvreau from Parent Creek. According to The Low Down to Hull and Back News August 29 - September 4, 2007, “…The aim of the study… is to… pinpoint the sources of any deterioration [of Parent Creek], such as high levels of nutrients. High levels of nutrients, like phosphates, can lead to higher chances of algae bloom…” [and of promoting the growth of Eurasian water-milfoil].

    > Read Association press release

Click on images to enlarge

Double-tap on images to enlarge

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Described as millions of "flecks" suspended in the lake water, a suspected blue-green algae bloom led to a call for action.
(Lac Gauvreau, August 25 2021)

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Blue-green algae bloom. No airborne or surface pollen was present when this photo was taken.
(Lac Gauvreau, fall 2019)

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A blue-green algae bloom can sometimes be mistaken for a "pollen dump." This bloom is characterized by a deep green hue.
(Lac Gauvreau, fall, date unknown)

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Not to be confused with an algae bloom, a typical "pollen dump" is characterized by its bright yellow colour, and is accompanied by airborne pollen dust.
(Lac Gauvreau, June 2021)


Blue-Green Algae: A serious problem everywhere — not only at Lac Gauvreau

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The worst lakes in Quebec: financial nightmares near lakes in poor condition

July 2, 2022 — (Google Translate) Better to find out about the quality of the water before spending a fortune on a cottage

Owners have seen their residence lose up to 25% of its value because it is located around a lake in very poor health.

No swimming, hard-to-sell residences, court battles, loss of revenue for cities; blue-green algae (cyanobacteria) or invasive alien plants like Eurasian watermilfoil not only poison water quality. They also poison the lives of local residents.

For the time being, the pandemic has caused a spike in cottage prices. But some may have bad surprises in a few years.

> Read a Google Translation of the original article

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Suspected late summer blue-green algae bloom inspires action

August 25, 2021 — In the midst of an unusually hot summer, the growth of what is believed to be cyanobacteria in Lac Gauvreau has led to a call for action. Enviro Lac Gauvreau has asked the municipality to assess the problem and help fix it, but as of this date, the Municipality has not responded. Residents are asked to help make their concerns heard by writing letters to the Mayor and the Administration regarding their concerns about this latest outbreak. A letter has been drafted that residents can send to select officials.
Stay tuned for updates.

> Draft letter (PDF)
> Draft letter (Word)

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Governments sign new agreement to protect Lake Winnipeg

Aug 12, 2021—Federal government announces more than $500K for projects focused on water quality, ecological health of lake

The federal and Manitoba governments inked a new 10-year agreement on Thursday committing to work together in support of the ecosystem health and water quality of Lake Winnipeg.

The memorandum of understanding between the two governments aims to find ways to collaborate on solutions to the various challenges facing Canada's sixth-largest freshwater basin, including ways of cutting down on nutrient loading that contributes to toxic blue-green algal blooms most summers.
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NCC closes 2 beaches at Lac Philippe over toxic blue-green algae observed near Parent and Breton beaches

Aug 5, 2021—Toxic algae observed near Parent and Breton beaches

The National Capital Commission (NCC) has closed two public beaches at Lac Philippe in Gatineau Park after cyanobacteria was found in the water.

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Deadly algae toxins claim life of puppy, seriously injure another dog near Renfrew

Jun 7, 2021Manager of Healthy Environments at the Renfrew County And District Health Unit said, unfortunately, hot conditions are ideal for blue-green algae to appear and to thrive in.
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Blue-green algae: Clear solutions for troubled waters

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…
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Quebec's blue-green algae problem bad and getting worse: researcher

July 30, 2019Quebec’s blue-green algae problem is as bad as it’s ever been and bound to get worse, according to researchers.