Monitoring of the Waipoua River at Colombo Rd in Masterton by the regional council shows that toxic algae levels are now high.

Clumps of the algal mats, which are brown or black, are also washing up on the river's edge. Toxic algae can kill livestock and dogs -- if your dog eats toxic algae, it can die very quickly. In humans, contact with toxic algae can cause vomiting, diarrhoea, skin irritations and other allergy-type symptoms.

"It's more than a month since there's been decent rainfall in the Waipoua River catchment, and this, combined with warm weather, has resulted in rapid toxic algae growth. The amount of toxic algae in the river is likely to remain high until there's a significant amount of rainfall," Greater Wellington senior environmental scientist Summer Greenfield said.

Masterton District Council has posted information signs at key access points along the river. Monitoring of Wellington waterways and coastal areas is carried out by Greater Wellington Regional Council and local authorities on a weekly basis over the summer months. Results of the monitoring and latest warnings are posted on


Other information about toxic algae, including a guide of what to look for and what to do if you are worried about possible contact with toxic algae, can be found at .

Nearby Henley Lake also has high levels of toxic algae and last week it was closed by Masterton District Council for all water activities.

More information on Henley Lake can be found at www.mstn. .

What to look for and what to do:
HOW TO SPOT TOXIC ALGAE: Toxic algae forms brown and black clumps at the river's edge or in parts of the river where rocks are exposed or it's shallow
IF YOU THINK YOU SEE TOXIC ALGAE: Avoid touching and swimming near toxic algae. Put your dog on a lead and move away from the river's edge
IF YOU THINK YOUR DOG HAS EATEN TOXIC ALGAE: Take your pet to a vet immediately
IF YOU ARE CONCERNED ABOUT SYMPTOMS FOLLOWING CONTACT WITH TOXIC ALGAE: Contact your family doctor River users, particularly those with dogs, should avoid parts of the Waipoua River because of increased growth of toxic algae, says Greater Wellington Regional Council, Masterton District Council and Regional Public Health.