Eye in sky on water quality
No-one likes to think they're swimming in polluted waters.
Thankfully there is a team of people making sure that doesn't happen in Auckland.
The water quality monitoring programme Safeswim was set up in 1999 and runs for 21 weeks annually from the first week of November till the end of March.
More than 95 per cent of water samples collected in the region comply with Ministry for Environment guidelines, Auckland Council environmental health specialist Sharon Tang says.
"Most of our beaches, including the eastern beaches, are quite safe to swim. But we do have some rare occasions where there is a failed result."
Every Tuesday samples are taken from 63 Auckland beaches and six freshwater sites, mostly by helicopter.
That makes sense in terms of consistency and timeliness because it means everything can be done on one day, Ms Tang says.
The samples are analysed at Watercare and results sent back to Safeswim within 24 hours.
What they're looking for is the level of enterococci bacteria.
The Environment Ministry defines the alert level as 140 enterococci per 100ml of water. If a test shows a reading between 140 and 280 enterococci further testing is carried out until the results return to normal.
When two consecutive levels are over 280, signs are put up at the beach telling people not to swim.
But if the initial reading is above 1000, signs are put up straightaway, she says.
There have been a couple of incidents last month.
Signs went up at Judges Bay for a few days when testing revealed a reading of 1800 enterococci. Swimming was not advised at Mission Bay on January 8 after a reading of 3000 enterococci was recorded.
The levels were back to normal within a couple of days.
Regional and environmental control manager Marcus Herrmann says there are various potential causes of contamination.
"There can be overflows that occur from the wastewater system into the stormwater system, there can be illegal discharges from boats and you can also get animal effluent from pets, birds and ducks."
Advice to swimmers is generally not to swim 24 to 48 hours after heavy rain, take care not to swim too close to outfalls and check the Safeswim website for updates.
Go to aucklandcouncil.govt.nz and search Safeswim for information.