Toxic Algae

KCDC Declares Algae Danger

Along Waikanae River

January 29. 2010
Te Arawai Bridge

The Kapiti Coast District Council has warned the public about the risk of toxic algae in the Waikanae River

The toxins produced by the blue-green algae can be fatal to dogs, which are particularly susceptible to exposure because they like to scavenge near water.

And the Council says contact with the blue-green algae toxins may also cause vomiting, diarrhoea and skin irritations in humans.

KCDC Environmental Health  are advising the public to take particular care around the Jim Cooke Park/Greenaway Road area of the Waikanae River, as the blue-green algae may be present in some places.

Warning Signs Posted

Medium-risk warning signs have been posted at key access points along nearby river reaches — including the Jim Cooke Park and Greenaway Road entrances to the river, and Te Arawai Bridge.

Continuing warm and dry weather, combined with lowering river flows, means the risk of a toxic algal bloom is increasing.

A two-tier warning sign system tells river users about the risk from toxic algae.

The medium-risk sign means users can still swim or walk their dogs but should keep an eye out for algal mats.

A high-risk sign means people should avoid contact with the river water during recreation and dog walking in that part of the river.

‘Dark Brown or Black’ colours

The Council says blue-green algal mats are actually a dark brown or black colour and grow as a thick layer on rocks in the riverbed.

Algal mats can come loose from the riverbed and wash up on banks or form floating ‘rafts’ in shallow water.  They should not be confused with the harmless bright green algae which grow in fluffy patches or long strands.

“Still Only a Potential Risk”

Currently, the Council says, the algal mat evident in the Jim Cooke Park area of the river is thick and sticking to the rocks, but not breaking off and dying which means it is still only a potential risk.

.The KCDC also says river users – particularly those with dogs, those who go swimming, or those who draw water from the river for stock or human consumption – should look out for exposed or easily accessible algal mats and should avoid any contact with them or water in the area.

If you see any exposed or easily accessible algal mats, contact Greater Wellington, (04 384 5708) or an environmental health officer at your local council.