Water Quality Issues

What is Blue-Green Algae?
Blue Green Algae in LakeThey are microscopic, plant-like organisms that occur naturally in ponds, rivers, lakes and streams. Although often blue-green, they can also be olive-green or red. Blue-green algae are not normally visible in the water, but populations can rapidly increase to form a large mass or scum called a bloom when conditions are favourable. Blooms most commonly occur in late summer and early fall. They thrive in areas where the water is shallow, slow moving and warm, but they may be present in deeper, cooler water.

Bloom Characteristics

  • Dense blue-green algae blooms may make the water look bluish-green
  • Like green pea soup or turquoise paint
  • Very dense blooms may form solid-looking clumps
  • Fresh blooms often smell like newly mown grass, while older blooms may smell like rotting garbage
Causes of the Algae
  1. Available nutrients such as phosphorus and nitrogen.
  2. Agricultural and storm water runoff
  3. Leaching from septic systems.
  4. In Ontario, phosphorus tends to be the nutrient that influences the growth of algae.

If you Suspect a Blue-Green Algal Bloom
  1. Assume toxins are present
  2. Avoid using, drinking, bathing or swimming in the water
  3. Restrict pet and livestock access to the water
  4. Contact your local health unit for information on health risks associated with blue-green algal blooms.
Bloom Near Your Water Supply?
  • Home treatment systems may not remove toxins and can get easily overwhelmed or clogged
  • Do not boil the water as it can increase toxin levels
  • Do not manually treat the water with chlorine or other disinfectants, as this could increase the toxin levels
Take these simple steps to prevent the growth of blue-green algae:
  1. Use phosphate-free detergents, personal care and household cleaning products
  2. Avoid using fertilizers on lawns, especially fertilizers that contain phosphorus
  3. Maintain a natural shoreline on lake and riverfront properties
  4. Reduce agricultural runoff by planting or maintaining vegetation along waterways and minimizing fertilizer use
  5. Check septic systems to ensure they do not leak into the water source