by Anita Moran anita.moran@dailypost.co.nz
Residents and visitors swarm to Rotorua's lakes during summer but some swimming spots are safer than others.
The regional council, Environment Bay of Plenty, warns the state of the lakes can change quickly - and often.
"When high nutrient levels occur, algal blooms
can appear making the water harmful for swimming," Environment Bay of Plenty scientist Paul Scholes said.
"Last year the water quality of Rotorua's lakes was generally good, but that did not mean it would be the same this summer," he said. Lake Rotorua could vary a lot, with different areas being safer to swim in than others.
The Lakefront and Ngongotaha were two of the worst areas, with high levels of nutrients. Holdens Bay and Hamurana were two of the better areas.
Mr Scholes said people should always keep an eye out for health warnings around the lakes.
"We will be undertaking regular bacterial monitoring. Generally the results are very good, but it pays to be cautious."
Lakes Tarawera, Okareka, Tikitapu (Blue Lake), Rotoma and Okataina had consistently good water quality.
"These are our pristine lakes, which we can swim in all year round," Mr Scholes said.
Lakes Okaro, Rotoehu, Rotorua and Rotoiti were susceptible to high nutrient levels which caused algal blooms and it could be dangerous to swim in lakes when there were blooms.
Different people could react differently, Mr Scholes said.
"If someone has asthma they could experience respiratory problems. If they suffer from allergies, they could develop a rash."
He said if high amounts of water were swallowed during algal blooms, internal organs could be damaged.
However, water with a high nutrient content was more dangerous to dogs than people.
Rotorua locals who regularly swam in the lakes were likely to have developed a level of immunity, Mr Scholes said.
If Rotorua experienced heavy rainfall, people should avoid areas where streams flowed into the lakes as the rain could wash in bacteria from surrounding scrub.
