What are Algal Blooms?

In the warm summer months lakes may suddenly appear to have a lumpy material on the Algal Bloomsurface which is blue-green, bright blue, grey or tan in colour, this is evidence of algal growth. When conditions are favourable algae can grow rapidly forming a large, soupy mass called a bloom.
Blue-green algae (or Cyanobacteria) are among the most common types of bloom producing algae. They form in shallow, warm, slow-moving or still water.

Why Do Algal Blooms Occur?

Blooms can occur naturally. However, they can occur when water bodies become enriched with nutrients due to storm water runoff, industrial effluent, agricultural runoff and effluent from waste management systems including faulty septic systems. Eutrophication is the process where a water body becomes enriched with nutrients, causing accelerated growth of algal blooms and plants to form. Increased quantities of algal blooms and plants deplete oxygen making it difficult for fish and other organisms which depend on oxygen to survive.

Why are Algal Blooms A Concern?

Most varieties of blue-green algae are relatively safe, however some produce toxins or poisons that can be harmful to humans and wildlife. The most common toxins are called microcystins. They are contained in the algae cells; as the algae break down naturally, through the human contact or introduction of corrosive chemicals, the toxins are released into the water.

Potential human health effects include:

• Itchy, irritated eyes and skin, due to external contact with the toxins.Algal Blooms Warning
• Headaches, fever, diarrhea, abdominal pain, nausea and vomiting, may result if the toxins are swallowed.

Symptoms seldom persist for more than two or three days.

Children and animals may be more intensely affected as they have lower tolerances than adults to the toxins. Children are likely to spend more time in the water, increasing their chance of accidentally ingesting contaminated water.

Occasionally, domestic animals such as cattle or dogs may be poisoned if they have no other source of drinking water. Animals that are old, very young, sick or weak may have lower tolerance levels and will be poisoned with much smaller amounts of toxin.

Effects Of Algal Blooms On The Health Of The Environment:

• The decomposition of algae uses up the oxygen dissolved in the water, this may deplete the oxygen to the extent that fish suffocate and die.
• The toxins can poison and kill waterfowl and other wildlife.

What Can I Do About Algal Blooms?

If the algal bloom has already grown in a water body you should take steps to protect your family and pets.

1) Prevent Negative Health Effects:

Recreational lake users should take special care during blooms and should treat any intense bloom with caution.

• Do not drink water from bloom-infested lakes and reservoirs.
• Avoid swimming and other water-related activities in areas with dense blooms until the water has been tested and declared safe.
• Supervise children and pets closely. Phosphate Free Detergent
• Provide alternative water sources for domestic animals and pets.
• Even after the bloom is gone, it is a good idea to wait until health authorities declare the water safe before swimming in it.

Treatment of algal blooms with chemicals such as, algaecides is not recommended as these can cause more toxins to be released into the water. For this reason it is better to prevent the algal blooms from occurring in the first place.

2) Prevent Algal Blooms from Forming

The best way to prevent algal blooms from forming is to reduce the amount of nutrients entering lakes. The main nutrient sources that can be controlled are sewage effluents, agricultural runoff, and industrial effluents. Cottage owners and recreational users of lakes can help reduce the nutrient inputs into lakes through awareness and individual action.

• Use phosphate-free detergents.
• Do not use fertilizers and maintain a naturalized shoreline on lakefront properties.
• Take steps to reduce agricultural run-off, such as planting on shoreline set backs.
• Ensure that septic systems do not leak into the water source by having sufficient distance between the septic system and water to prevent nutrients from the septic from reaching the water.