A rapid response has been initiated by Bay of Plenty Regional Council to try and avert an algal bloom in Okawa Bay, Lake Rotoiti.
Bay of Plenty Regional Council general manager natural resources Warwick Murray said the recent hot, still conditions had encouraged algal growth in the sheltered bay.
"Our standard monitoring of cyano-bacteria or blue-green algae has showed increased levels over the past two weeks," he said.
"With the increased levels of harmful blue-green algae we have been monitoring the situation closely," Mr Murray said.
Latest monitoring results today have recorded a bio-volume of 21mm3/L and this is at a level when a health warning can be issued for recreational contact.
"To try and prevent an algal bloom and resultant health warning alum will be applied to the lake surface by boat on Sunday. This will lock up the nutrients so that the algae cannot feed off them and potentially halt an algal bloom," Mr Murray said.
"In 2011 similar levels of cyano-bacteria were recorded and we successfully prevented an algal bloom. We are hopeful for the same result this time," he said.
"In accordance with the resource consent conditions all properties that have bay frontage have received a letter advising them of the alum application and signs have been posted at the boat ramp."
A meeting will be held at the Okawa Bay boat ramp at 10am tomorrow to discuss the spraying.
"Lake Rotoiti has had the best water quality in decades over the last year and overall water quality in the wider lake is good.
"Okawa Bay is quite sheltered and in the right climatic conditions levels of blue green algae can increase and that is what we are seeing at the moment," he said.
It is not safe to enter the water while spraying is occurring.
You should never swim or take part in any activity that may result in accidental consumption or exposure to water affected by algal blooms if a health warning is in place for that area, even if there are no visible signs of a bloom.
For information on health warnings in the lakes visit www.ttophs.govt.nz and click on health warnings or call 0800 221 555 and select option 7 to speak to the on call health protection team.