“Finding these bacteria in waterways suggests other pathogens, which are harmful to human health, may also be present,” Hurst said.
“As E. coli and enterococci are not visible to the human eye, taking samples ... is a key way we can help people to make informed choices about where to swim this summer.”
Samples are taken once a week and sent to an independent laboratory for analysis, with results posted on the Land, Air, Water Aotearoa (LAWA) website.
Horizons does not close the swim areas when contamination levels breach recommended safety standards. Instead, it provides swimmers with the information so individuals can make informed choices on their own.
“The decision to swim always remains with individuals,” Hurst said.
“However, test results can help to inform people about where and when to swim.”
He said people could view alternative spots on the LAWA website if their go-to was deemed unsuitable for swimming at the time.
“While not being able to go to a usual spot is not ideal, it does give the opportunity to explore other swim spots across the region.”
As a general rule, swimmers should stay away from waterways, especially rivers, for 72 hours after heavy rain.
Heavy rainfall can increase levels of faecal contamination through faster-flowing water and there may be new hidden debris underneath the surface.
“Be sure to check for large objects in areas where you may be swimming – this is very important if you are planning to dive, do bombs or pop a manu," Hurst said.
Cyanobacteria is another common toxin that affects animals and people that often found around freshwater. It may appear as green scum in or above lake water, or as black mats on rocks in rivers, Hurst said.
For humans, contact with cyanobacteria can cause gastroenteritis, respiratory illness, and ear and skin infections.
The risks are much higher and more harmful for pets such as dogs, and ingestion can be serious.
“Cyanobacteria gives off a musty smell that dogs seem to love,” Hurst said.
“Be sure to keep an eye on your pets around waterways, especially if cyanobacteria is present in the area.”
Hurst urged caution around any waterway or beach this summer.
“Rivers and beaches across Aotearoa New Zealand can be unpredictable and their power easy to underestimate.
“Do not enter the water alone, actively supervise children and stay out if you are not a confident swimmer.”
Swimming close to cliff faces should be avoided, as slips may happen at any time. People should call 111 if any water emergency arises.
More information on how to stay safe in the water is available on the Water Safety New Zealand website.
