Toxic algae at Henley Lake

Tests carried out by Masterton District Council have shown concentrations of cyanobacteria (toxic algae) have increased at Henley Lake, and it is recommended that visitors avoid contact with the water, in particular children, pregnant women and older people.

Cyanobacteria produce toxins that are harmful to humans and animals if swallowed or through contact with skin (such as may occur when swimming or rowing). Exposure to cyanobacteria may cause symptoms such as skin rashes, nausea, tummy upset, and tingling or numbness around the mouth or tips of fingers. Pregnant women, children and the elderly are more likely to be affected. If you experience health symptoms after contact with the Lake, consult a doctor. Your doctor will let the Public Health Unit know.

Dogs may also be at risk. Throughout New Zealand a number of dogs are known to have died after eating cyanobacteria at the edges of water bodies. Keep dogs out of the water, and away from the edge. If you believe your dog has eaten contaminated material, contact your vet immediately.

Cyanobacteria occur naturally but can increase rapidly during summer months. If the water is cloudy, discoloured or has small globules suspended in it, avoid all contact. Not all cyanobacterial blooms are visible to the naked eye and toxins can persist after the bloom has disappeared. Cyanobacterial concentrations can change quickly with changing environmental conditions (eg wind). If a health warning is in place, avoid contact with the water.

Masterton District Council monitors cyanobacteria weekly at Henley Lake during the summer and the public will be advised of any changes in water quality that could represent a health risk. Visitors are advised to look at the signs around the Lake or the check the Council’s website for the most up to date information.

For further information visit the Masterton District Council website https://www.mstn.govt.nz/ or contact the Council on 06 370 6300.