Water samples taken from the lagoon by the Otago Regional Council last week and tested by the Cawthron Institute in Nelson, showed no signs of any of the toxins which can be produced by the cynaobacteria algae. Other tests showed there were still extremely high levels of algae present in the lagoon.
In a statement to the Otago Daily Times, the council's resource science manager, Dr Dean Olsen, said the toxicity tests looked for the presence of seven toxins in the lagoon.
Although the negative tests were good news, the health warnings would remain, Dr Olsen said.
The warnings have been in place for about two weeks.
Cyanobacteria caused skin irritation and respiratory reactions in some people, even in the absence of toxins.
Until the algae levels subsided, people and animals should avoid contact with the water in the lagoon.
It was the first time the specific algae had been found in the lagoon.
Residents raised concerns about stormwater run-off from neighbouring properties causing the algae, but the regional council found no evidence linking the two.
Cyanobacteria occurred naturally but could increase rapidly during summer months.
