The Otago Regional Council investigated the possibility stormwater runoff was the source of the cyanobacteria algae bloom, after concerns were raised by residents.
The council's environmental monitoring and operations director Scott MacLean said no link had been found between stormwater runoff and the algal bloom.
Warnings were placed alongside the lake by the regional council last week after high levels of the potentially toxic algae were found.
It was the first time the algae had been found in the lagoon.
What caused the bloom was still not known but it could appear naturally and warm weather could exacerbate its growth.
It would be at least two weeks before the warnings were dropped.
ORC resource science manager Dean Olsen said water samples were collected from the lagoon on Tuesday and tests were carried out yesterday.
Results from the tests were expected today but the warning would stay in place no matter what level of the algae was found.
''The levels observed last week were very high and warning will likely stay in place for another two weeks.''
It would take at least two samples with low levels of the algae present for the warning to be downgraded, Dr Olsen said.
Toxins produced by the algae could be harmful to humans and animals if swallowed or through contact with skin.
Dog owners are warned to be especially vigilant as the algae was particularly toxic to canines.
The regional council would continue to monitor the lagoon and update the public as new information became available.
Albert Town Residents Association president Bruce Hebbard said speculation about what caused the bloom was pointless.
''Until we have the facts and know exactly what has caused the algae to appear, there is no point in blaming it on anything.''
There was a possibility a bloom had occurred in the past but had not been noticed as the area around the lagoon was not as accessible as it was now, Mr Hebbard said.
People in Albert Town were proud of the lagoon and were rightly concerned about its health, he said.
