Blue-Green Algae

Environmental Health

Recreational Water - Blue-Green Algae

As of July 1, 2015 the inspection, compliance and enforcement functions from several provincial government departments came together under Nova Scotia Environment.

Blue-green algae are primitive, microscopic aquatic plants, which live in fresh water, such as ponds and lakes. In the late summer and early fall, when the weather is warmest, blue-green algae may multiply rapidly causing visible discoloration often referred to as blooms.

Blue-green algae blooms may occur in fresh water ponds, lakes, bays and inlets. In recent years, these blooms have occurred in several locations throughout Nova Scotia.

Algae blooms can be recognized because the bloom may form strings, flakes, or globules and may look like fine grass clippings in the water or a soupy mass. The blooms may also have a distinct odour. A fresh bloom can smell like newly mown grass; older blooms may smell like garbage.

During an algae bloom, you should refrain from swimming, bathing or drinking the water. Although many forms of blue-green algae are relatively harmless, toxins, if present, can cause skin irritation which may be harmful to the health of both humans and animals. When contact is made with water containing toxins, the following health effects may occur:

  • Itchy, irritated eyes and skin, if you swim or bathe in contaminated water; and
  • If swallowed, symptoms such as headaches, fever, diarrhea, abdominal pain, nausea and vomiting may occur.

Since children are likely to accidentally swallow more water, spend more time in the water than adults, and due to their lower body weight, they are at a greater risk of developing symptoms due to blue-green algae. Pets are also at risk and should not be allowed to drink or swim in the water.

In the event of an algae bloom, avoid the following activities:

  •  Do not drink, swim, bathe, shower or brush your teeth with the water.
  •  Do not allow children, pets and livestock to drink or swim in the water.
  •  Do not boil the water. Boiling water may release more toxins into the water.
  •  Do not cook with the water. Food may absorb toxins from the water.
  • You may wash dishes or other objects, as long as you rinse them with uncontaminated water and dry them thoroughly.
  • Do not water your vegetable garden with the water. If this is unavoidable, water the base of plants rather than the stem or leaves.
  • Do not treat the water with a disinfectant like chlorine (bleach). This may break open algae cells and release toxins into the water.
  • Do not rely on jug or pitcher-type filtration systems, as they do not fully protect against toxin poisoning.
  • Use alternative water sources, including bottled water, carted or tanked water, or call a water treatment specialist for help.