Following heavy rain, water quality vigilance urged for swimmers

AUCKLAND: As New Zealanders enjoy summer, many are asking where is it safe to swim.

It is a relevant question after the Auckland Council’s Safeswim website showed a ‘‘high risk’’ of illness from swimming at dozens of beaches in the region last weekend.

Heavy rain had added significantly to the country’s polluted waterways problem.

Earlier more than 50 beaches had a red alert on the Safeswim website.

Land Air Water Aotearoa senior scientist Anna MadaraszSmith said the national water quality monitoring body’s website had data from hundreds of lakes and rivers across the country, enabling people to make safe choices about whether they should swim in these locations.

She said water quality models also featured on the website and predicted levels of faecal bacteria exceeding national guidelines for swimming.

‘‘We collect all of the environmental monitoring information, which is collected by regional authorities in New Zealand and it’s displayed on our website.’’

The safety outlook for waterways was improving as rainfall receded.

‘‘It’s looking good at the moment, but we have to remember we’ve had a lot of rain between Christmas and

New Year period, unfortunately.

‘‘We know when we get a lot of that heavy rain, it rushes through your gutters, it’s coming off the land into the water system, flowing into your lakes and rivers and ocean and that carries everything with it — anything on the roads and that can be litter, it can be faecal material from animals.

‘‘So that’s why we say to stay out of the water for two or three days following heavy rain.’’

Water discoloration and thick algae were other signs of water contamination, and signals to stay out. Other bacteria hotspots included lagoons, which in general were not ideal places to swim and usually posed a risk due to current flow and catchment area.

‘‘These are areas where rivers come in and it becomes more slowflowing. It gets a bit warmer and you may have a lot of ducks, birds, geese. They can be more susceptible to these higher levels of faecalindicator bacteria.’’

The website’s colourcoded scheme is based on the New Zealand Guidelines for Recreational Water Quality, green meaning the risk is acceptable, amber denoting higher risk, and red that the site is unsuitable for swimming. Black signifies there has been a sewage overflow and the area is out of bounds.

www.lawa.org.nz/exploredata/swimming.