8.2.4.Algal blooms

Algal blooms may vary in colour from green to blue, red, brown, dark green and black. Some will be easily seen as a scum, while others will be spread evenly through the water or possibly concentrated at depth.
Blue-green algal blooms can cause unpleasant smells and tastes in the water and produce a variety of toxins, including liver toxins, neurotoxins and endotoxins which cause skin irritations. The toxins can persist for weeks, and are a potential health risk to both humans and livestock. However, blue-green algal blooms are not always toxic, and those that are may change their toxicity slowly over a period of weeks to months.
There are reported livestock deaths due to the toxic effects of blue-green algae. As not all toxic algae produce blooms that are readily recognisable, stock deaths and illness should be reported to your local Livestock Health and Pest Authority (LHPA).
Dogs are very susceptible to blue-green toxins, especially if they swim in an algal bloom.
In humans, the toxins produced by blue-green algal blooms can cause nausea, headaches, vomiting, abdominal pain, diarrhoea, gastroenteritis and even paralysis. Boiling affected water will kill the algae but will NOT destroy the toxins and in some cases will cause more to be released in to the water. Some have even been known to become more dangerous as a result of boiling.