Water quality at nine Wellington beaches will be tested again today after rising bacteria levels led to them being declared unsafe for swimming yesterday.
Unsafe levels of enterococci bacteria - 280-plus bacteria per 100ml of water - were recorded at Owhiro Bay, Island Bay, Seatoun Beach, Worser Bay, Scorching Bay, Mahanga Bay, Shark Bay, Hataitai Beach and Plimmerton Beach.
The Hutt River also had unsafe levels of the bacteria at the testing site near the Melling Bridge, though test sites at the river north of Silverstream came back clear, from tests taken on Monday.
A total of 15 recreational bathing sites monitored by the Greater Wellington regional council were unsafe for swimming at 5pm yesterday.
Greater Wellington senior environmental scientist Summer Greenfield said the many unsafe sites were the result of this week's downpour.
"In heavy rain, there's a much- increased chance of a sewer overflow. We were notified, in Wellington city, Porirua and the Hutt, there were a number that occurred over that Monday and Tuesday period . . . plus whatever has accumulated on the streets over [the preceding] dry period."
Ms Greenfield said enterococci indicated the presence of other bacteria that posed a risk to human health, such as campylobacter and salmonella, which were too expensive to monitor.
The elderly and young children are more at risk of being affected by such bugs, which can cause stomach upsets.
The council's general warning was to not swim anywhere for 48 hours after heavy rain, she said.
"After particularly heavy rain like we had . . . I would maybe be a bit cautious about swimming today too." She said most sites were expected to return to normal when results from the retests were made available today.
Though some sites - Owhiro Bay, Island Bay, Worser Bay, and Mahanga Bay - had quite high levels of enterococci, these were expected to return to safe levels today. But if unsafe readings were found again, local councils would investigate.
- © Fairfax NZ News
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