Algae Warning January 2009

Fri 16 Jan 2009

A nasty surprise could be waiting for people hoping to make the most of summer by heading for many of the region’s rivers and streams

Horizons Regional Council scientists warned yesterday that outbreaks of potentially harmful blue-green algae were widespread in the upper Manawatu River and its tributaries upstream of the Ashhurst Domain, though there were some clear swimming spots on the Pohangina River.

The algae, which can kill dogs and harm humans, has also been confirmed in Palmerston North at the end of Albert St and in the Oroua River at Awahuri.

Horizons environmental scientist Kate McArthur said the lack of rain and continuing warm weather were creating ideal conditions for the slimy black Phormidium growths to take hold in shallow reaches of the region’s rivers and streams.

“While we have been able to confirm the algae is present in a significant number of popular swimming spots, people should keep themselves and their pets safe by assuming that all waterways may have Phormidium present and they should check for obvious signs before swimming,” said Ms McArthur.

“Young children and babies are at greater risk, and dogs should be kept away from any river with obvious signs of growth.

“Fishing in areas with signs of the algae is probably okay but fish might taste muddy and should be thoroughly washed with clean water. Don’t eat the kidneys and liver.”

Ms McArthur said rivers with better water quality were generally likely to have less algal growth and be safer for swimming.

“Anyone wondering if they have found a safe place to swim should check upstream for shallow areas where the water is broken, such as riffles or rapids. If there’s any slimy black growth in the water, or dried material on the river’s edge, swimming is probably not advisable.”

She said checks yesterday showed no growths on the Pohangina River at Piripiri, Mais Reach and the Totara Reserve, though anyone visiting those areas should check for themselves.

“While these areas were clear and fine for swimming when we checked them, people should remain vigilant as growths and blooms can develop rapidly at any time.”

Ms McArthur said algae had been confirmed in the Waikawa Stream downstream of SH1.

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