Toxic algae in Lake Ngā Roto

Lake Ngā Roto. Photo / Dean Taylor

Dog owners have been advised to be vigilant after algal bloom (cyanobacteria) was found in the northwestern area of Lake Ngā Roto.

Waipā District Council's customer and community services group manager, Sally Sheedy, said although there was no public health warning in place for the lake, the council was being extra vigilant.

"This is a very localised algal bloom that is not expected to get as bad as it could be in the summer months. But we still want to ensure people are well aware of the issue.

"We're advising people and their dogs to avoid water that has a green colour or scum when enjoying windsurfing, kayaking, or other activities at the lake."

Lake Ngā Roto boasts leafy boardwalks, and visitors can also learn about nearby historic pa sites. Photo / Outdoor Kid

The algae look like dark brown to black mats and can produce toxins harmful to people and animals.

Dogs are especially susceptible to the toxins produced by the algae which if ingested, could cause significant illness and could even be fatal.

Signs that a dog might have consumed toxic algae include lethargy, muscle tremors, fast breathing, twitching, paralysis, and convulsion.

"Dog owners, especially as duck hunting is in full swing, should be careful and not allow their dogs to swim in the water," Sally said.

"Animals that show signs of illness after coming into contact with algal mats should be taken to a vet immediately."

In people, exposure to cyanobacteria could cause skin rashes, nausea, stomach cramps, tingling and numbness around the mouth and fingertips.

Sally also urged people not to handle fish in areas of the lake where algal bloom is present.