An iconic Auckland ocean swim is moving locations for the first time in 14 years due to water quality issues at beaches on the city's North Shore.

Organisers of the "King of the Bays" event have moved the swimming races from Milford beach to Devonport.

The shift follows frequent "red readings" on Auckland Council's Safeswim website relating to Milford and Takapuna beaches.

The original location of the event had featured a 2.8km swim from Milford to Takapuna beach and also included multiple shorter swims out from the Takapuna shoreline.


King of the Bays event director Scott Rice said he refused to compromise swimmer safety.

"It's really disappointing to have to move after 14 years, but it's something we felt we had to do," he said.

"Our decision is aligned with the fact that we are passionate about creating a safe, fun, sustainable environment for our participants."

The water quality safety readings typically follow periods of heavy rain, which often causes wastewater to overflow.

Safeswim provides water-quality forecasts and up-to-date information on health and safety risks at 84 beaches and eight freshwater spots in Auckland.

It has three levels: green - meaning low risk and safe to swim, orange - low to moderate risk but still safe, and red - high risk and unsafe for swimming.

Warnings have been issued at dozens of Auckland beaches over start of this year following a handful of extreme weather events.

Last week changes to Safeswim indicators at Takapuna beach caused at least one of the weekly swimming races held at the beach to be cancelled.

Takapuna resident Ian Gunthorp said on Tuesday during swimming races at Takapuna beach that Safeswim indicators showed orange for the afternoon and red for the evening.

"At 5.50pm juniors were allowed to swim but at 6.30pm a larger body of swimmers and paddlers were not allowed to race.

"Neither in the intervening period nor immediately prior was there any rainfall or toxic spill and no perceptible change in tide or wind and yet a computer dictated that the surf club support, and therefore the races, had to be cancelled."

Rice said Devonport and Cheltenham had shown 100 per cent "green reading" results over the past three months, making the revised location safer for participants.

The event was the last of a series of seven events around the country, held each summer.