Auckland mayor Len Brown says he would swim in some parts of Manukau Harbour despite a new study showing there are high risks of getting sick.
Auckland Council's first State of the Environment report since 2009 points to a gradual decline in the quality of marine and freshwater.
It says people who swim at more than a quarter of monitored swimming spots in the city face a moderate to high risk of becoming sick.
Mr Brown told Morning Report parts of Manukau Harbour are safe for swimming but the council was keeping a close watch on areas near industrial zones.
Listen to Len Brown