MEDIA RELEASE

Short-lived algal blooms on Lake Rotoiti

For immediate release: Tuesday 9 December 2003

Lake Rotoiti has started to develop its first algal blooms of the summer but so far they are sporadic, localised and do not last long, says Environment Bay of Plenty.

The latest tests show harmful blue-green algae are beginning to build up in the lake, which was shut down by algae-prompted health warnings in late January this year.

Paul Dell, the regional council’s group manager of regulation and resource management, says it is too soon to tell whether blooms will be as intense as last summer. A lot will depend on the weather, he says.

Recent hot, still conditions encourage algal growth and “have not helped the situation at all”. But windy conditions are predicted before Christmas, which may help stall the development of any future blooms, he adds.

Environmental scientist Matthew Bloxham, who runs Environment Bay of Plenty’s blue-green algae sampling programme, says the start of the summer has been an uncertain period. “Blue-green algae numbers are beginning to build and there have been intermittent, localised blooms. But they have not lasted long.”

Last week’s monitoring shows a general rise in algae counts in Lake Rotoehu, no significant change in Lake Rotorua and notable increases, followed by falls, at a handful of sites around Lake Rotoiti. Okawa Bay continues to build slowly, while Te Weta Bay and Okere Arm are fairly static.

Environment Bay of Plenty will be sampling blue-green algae from five different lakes over summer, most of them weekly. Lakes Okataina and Tarawera are included this year. More lakes and sites within some of these lakes will be tested more frequently, Mr Bloxham adds.

However, he warns, people still need to check the water to see if it’s safe before using it for recreation. “Wind can sweep large amounts of algae into a bay over a matter of hours, causing it to build up to dangerous levels. People should assess lake conditions carefully before getting into the water, even if there are no warnings in place.”

Generally, if the water looks milky green or is a dirty brown colour, or has globules floating in it, play it safe.

Lake users can check the current status of blue-green algae warnings in a lake or bay on www.envbop.govt.nz.

ENDS

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