Safe to swim? Confusion over swim safety messages

BLOOM PLUME: Waterskier Ethan McKenzie was carving up Lake Wiritoa yesterday. Algae levels are steady but local authorities are urging lake users to be cautious. PHOTO/LEWIS GARDNER

Is it safe to swim in our lakes?

One agency says yes, another says maybe.

New readings of algea counts have come in at Lake Wiritoa just south of Whanganui city and Duddings Lake north of Bulls. Horizons Regional Council say the counts are acceptable, while quasi-government agency LAWA (Land, Air,Water Aotearoa) urges caution.

Nicole Taber, communications lead for LAWA, said it wasn't that the organisations were saying different things; rather it was a matter of words.

"Horizon's message gives the lakes an amber status while LAWA gives them a caution status, but both are based on similar sampling and both mean the same," Ms Taber said.

"The public need to know that both LAWA and the regional council are aligned on this. We are nation-wide and use one word but local councils have their own language. But the overall message is the same - we're urging caution," she said.

Both organisations say while the lakes are usually suitable for swimming younger children and older people may be at increased risk at times. And if potentially toxic algae blooms are present people should avoid contact with the water.

Horizons spokesman Barry Gilliland said latest samplings indicate that recreational use should be "okay" even though lake edge temperatures were "very warm".

But Mr Gilliland said algae density can change quickly, so people heading to either lake needed to be watchful.

"If you see green particles forming a surface scum on the lake, avoid contact with it. Our standard precautionary advice is to mix the lake around using a motor boat, if that option's available, before getting into the water."

Levels of blue-green algae - its scientific name is cyanobacteria - can change rapidly and if you see a light green coloured scum forming on the lake avoid contact with the lake water and keep animals out.

Symptoms from drinking water that contain blue-green algae can be nasty and include headaches, nausea, fever, sore throat, dizziness, stomach cramps, diarrhoea, abdominal pain, vomiting, muscle aches, mouth ulcers, and blistering of the lips.