Mission Bay and St Heliers are among two dozen beaches that have been issued a high risk swimming alert for contracting illness.
The alerts are being issued from Auckland Council's Safeswim programme, which monitors water quality and swimming conditions around the city.
This morning Mission Bay, St Heliers, Point England and Milford South beaches were coded "black", signalling a very high risk of illness from swimming.
More than a dozen other popular swimming spots in West Auckland and on the North Shore were coded "red" for a high risk of illness from swimming.
According to the Auckland Council, the city's ageing storm water infrastructure often overflows after heavy rain, leading to contamination at some beaches.
That contamination can come from a variety of sources including birds, dogs, livestock, onsite wastewater systems or wastewater overflows.
Those packing their beach bags in Auckland this morning are advised to check the council's website for more details.
rnz.co.nz
