Summer swim spot testing starts

Horizons Regional Council has begun its summer swim spot monitoring programme so everyone in the region can check the water quality of their favourite site before they head out.

Every year from November 1 to April 30 Horizons visits about 80 sites across the region to collect samples that go to an independent laboratory for testing. Results are uploaded to lawa.org.nz weekly for the public to check before hopping in.

Environmental monitoring scientist Kelly Le Quesne says the team monitors the levels of faecal indicator bacteria and potentially toxic algae (cyanobacteria) in the water.

“Faecal contamination in water is measured by testing for E. coli at freshwater sites and Enterococci at coastal sites,” she says.

“The presence of these bacteria in waterways suggests that other pathogens, that are harmful to humans, may also be present. E. coli and Enterococci are not visible to the human eye so the team take samples and send them to an independent lab for processing.

“Potentially toxic algae includes cyanobacteria which appears as black mats on rocks in rivers and as green scum in and above water in lakes. This algae can be toxic to dogs, as well as humans.

“Staff observe these algae onsite using a bathyscope (underwater viewer) in rivers. In lakes a sample of the water is taken and examined under a microscope.”

Coming into contact with water where these organisms are present in sufficient quantities can lead to conditions such as gastroenteritis, respiratory illness, and ear and skin infections, Le Quesne says.

“Once we get the results we update Land Air Water Aotearoa so people know which sites are suitable for swimming.”

While the public should always check Lawa's website for water quality results, there are other things swimmers should be aware of, particularly around rivers.

“If it has been raining heavily within the last 72 hours please stay out of the water,” she says.

“The flow is often faster than usual and there can be high levels of faecal contamination which could make swimmers unwell. Once you're back at your local swim spot it is also important to remember that things may have changed beneath the surface since you last swam there.

“New Zealand rivers and beaches can be unpredictable and deceptively powerful, so don't enter the water alone, actively supervise children, and if you aren't a confident swimmer stay out. We also recommend checking the water is clear and there's no large debris around.

“Finally, don't swim close to cliff faces and in an emergency call 111. Last summer our region experienced water related tragedies, so it is important that we all remember this key safety information.”

Horizons is updating signs at regional swim spots to highlight safe water practices.

Land Air Water Aotearoa holds water quality information for swim spots around the country. Interactive maps show each of the swim spots tagged by a red, amber or green location marker to indicate that week's results and whether the water quality is appropriate for swimming based on the Ministry of Health's guidelines.

“This means that even if someone is heading away, they can still use the website to check results or find swim spots.” Le Quesne says.

Sites tested tend to be the most popular in an area.

“However, this summer we will also be asking people to provide feedback on the sites we monitor and whether we should consider alternatives.” Keep an eye on freshwater. horizons.govt.nz