A raft of "high risk" swimming warnings have hit dozens of Auckland beaches.
Auckland Council has issued a red warning for over 50 Auckland beaches after water quality measuring systems indicated high levels of faecal contamination.
The red warning is triggered when there's a greater than 2 percent chance of getting sick from swimming at a beach.
St Heliers, Herne Bay, Browns Bay, Cockle Bay and Beach Haven are all on a short-term high-risk warning.
Further south, Glenbrook Beach and southern Manukau's Sandspit have also been labelled high-risk.
The warnings come after wastewater systems were overwhelmed by heavy rain during the weekend. The Council's Safeswim website has issued 12 beaches with a heightened long-term warning, advising people: "Do not swim."
Long-term high-risk areas
- North Piha Lagoon
- Piha South Lagoon
- Bethells Lagoon
- Fosters Bay
- Titirangi Beach
- Wood Bay
- Green Bay
- Oakley Creek
- Meola Reef
- Cox's Bay
- Little Oneroa Lagoon
When contaminated by human or animal faeces, the water can contain disease-causing bacteria, viruses and protozoa, which can cause illnesses and infections.
Safeswim's water quality forecasts take rainfall, wind, tide, sunlight and beach type into account.
There are no beaches currently at a black alert or "very high risk" of illness from swimming, which occurs when water is directly contaminated by human faeces.
According to the Safeswim website, their water forecasts are built using high-frequency targeted sampling on top of historical monitoring results, and are underpinned by the best available meteorological data.
Safeswim's forecasts are automatically overridden if sensors detect unpredicted events - like a wastewater overflow in dry weather - that are likely to cause a public health risk.