Masterton District Council has closed Henley Lake for recreational purposes and issued a health warning after tests show concentrations of cyanobacteria (toxic algae) to be at high levels.

Toxic algae (cyanobacteria) is found in the majority of lakes and rivers in New Zealand. Under certain conditions, including warm temperatures, prolonged periods of sunshine and low water flow through the lake, the algae can proliferate to very high numbers.

Community Facilities and Activities Manager Andrea Jackson said the most recent testing at Henley Lake has confirmed very high concentrations of cyanobacteria (toxic algae).

“We are advising people to avoid all contact with water in Henley Lake in particular children, pregnant women and the elderly. People are still free to use the greenspace but should keep to the paths and away from the waters edge,” Ms Jackson said.

“Dogs may also be at risk; keep your dogs out of the water and away from the edge. Anyone who believes their dog may have eaten algae or ingested water should contact their vet immediately,” Ms Jackson said.

“Cyanobacteria produce toxins that are harmful to humans and animals if swallowed or through contact with skin such as during 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 notify the Public Health Unit.

Masterton District Council monitors cyanobacteria weekly at Henley Lake during the summer and the public will be advised of any other changes in water quality that could represent a health risk.