Most Wairarapa rivers have been deemed not fit for swimming by Land Air and Water Aotearoa’s [Lawa] predictions.
All Wairarapa rivers are either marked as unsuitable for swimming because of a predicted E.coli status after rainfall in the Tararua Range, or caution has been advised for toxic algae blooms.
Floating mats of toxic algae have been spotted at the popular north-Masterton Double Bridges swimming spot, while more of the toxic algae can be found growing on the side of littered plastic in the river.
Greater Wellington Regional Council [GWRC] had previously extended its concerns about rubbish dumping in rivers across Wairarapa and the wider Wellington Region.
In 2021, GWRC called for a unified community effort to protect Wairarapa’s rivers, which were facing constant pollution, contamination, and desecration from ongoing rubbish dumping.
Various cleanups had included the removal of cars, household waste, concrete rubble, and rotting animal carcasses.
“The mindless rubbish dumping we’ve seen take place, especially along Featherston rivers this summer, is a huge risk to water health, human health and the precious species that live in and around our rivers,” Wairarapa Committee chair Adrienne Staples said.
“Quite simply, this pollution kills wildlife and stops the community from connecting with our rivers – recreationally, through collecting mahinga kai or for general wellbeing.
“The damage to our rivers could be irreversible – they won’t be the same for future generations if people continue to pollute,” she said.
The toxic algae smells vaguely like musty clothing and dirt, and is very attractive to dogs — however, it is highly toxic to animals and children.
Lawa said heavy rain flushed contaminants from urban and rural land into waterways, and it advised people not to swim for two to three days after heavy or prolonged rain – even at sites that generally
have good water quality.
“Check that the water is clean and clear before taking a dip.”
It said potentially toxic algae could rapidly bloom to harmful levels, and not all freshwater sites were monitored for toxic algae.
“Play it safe — if you can see toxic algal blooms in rivers or lakes, avoid contact or choose another site to swim.”
Potentially toxic algae, which is scientifically known as cyanobacteria [and isn’t classed as algae], are naturally occurring but some can produce toxins that are harmful to animals and humans.
Lawa said cyanobacteria played an important role in many land and aquatic ecosystems and could be found in both near-pristine waters and those more impacted by land use.
“In aquatic environments, cyanobacteria can multiply and form blooms suspended in the water [known as planktonic] or dense mats attached to rocks on river beds [known as benthic].
“Planktonic blooms are generally found in slow-moving waterways such as lakes, while benthic blooms usually occur in rivers.”
It said potentially toxic algae differed from harmless bright green algae, which often formed long filaments [thread-like structures].
GWRC said the Hutt River was one of the first places in the Wellington Region to have warning levels of toxic algae.
“Toxic algae is deadly to dogs, and can make people sick.
“Dogs should be kept on leads away from the water, and children should be supervised,” it said.
GWRC said there were detached algal mats on the river’s edge at these sites, making them highly risky for dogs.
It said preventing your dogs from eating toxic algae is better than any known treatment.
“If you have been in contact with toxic algae and are feeling unwell see your doctor or ring Healthline on 0800 611 116.”
GWRC said if you thought your dog had swallowed toxic algae, take them to the nearest vet immediately.
The swim status of popular Wairarapa swim spots, as well as spots all over New Zealand, can be found on Lawa’s website.
