A sample confirmed the presence of the toxic blue-green
algae. Photo by ORC
Warnings have been issued to swimmers and other water
users following the appearance of a toxic algal bloom in Lake
Waihola and Tomahawk Lagoon.
A sample taken from the lake had confirmed the presence of
the toxic blue-green algae, ORC director of environmental
information and science John Threlfall said.
The algae occurs naturally in a variety of water quality
The water in Waihola looked very green at the moment, owing
to the algae, which had the potential to produce a series of
toxins which were then passed to the water; this could cause
illness in people and animals, Dr Threlfall said.
The degree of toxicity was impossible to accurately predict:
however, the algal samples would be tested for toxicity early
next week, he said.
Southern District Health Board Medical Officer of Health Dr
Marion Poore said people swimming in water with increased
levels of algal bloom had been known to develop allergic
reactions: asthma, eye irritations, rashes, blistering around
the mouth and nose, and gastro-intestinal disorders,
including abdominal pain, cramps, and diarrhoea.
People should not swim in areas affected by the algae, and
other water users, including fishermen and boat users, should
exercise caution, she Poore said.
People could safely walk their dogs on the lakefront,
provided they kept them well away from the water.
"In the case of illness or suspected illness after swallowing
water containing algal bloom, seek advice from your doctor.
If your animals become sick, contact your veterinarian
immediately," Dr Poore said.
Dr Threlfall said: "We appreciate that a holiday weekend is
upon us, and that swimming in the lake is a popular pastime,
but we consider the safety and health of people and their
animals to be paramount."
The council has put up warning signs at the locations where
the algae has been found, and will continue to monitor the
situation, along with Public Health South.
Dr Threlfall said people should be wary of the possible
presence of toxic algae in rivers and lakes throughout the
region this summer. ORC and PHS will continue to monitor the