Water water everywhere, and not a place to swim

Auckland beaches spent 25 percent of last summer in a non-swimmable state, as record levels of rain fell on the region.

The unprecedented amount overloaded the capacity of the stormwater and wastewater networks, leading to widespread water quality warnings at the city’s beaches.

It represented a low point for the city since the current regime of recording began in 2017, when new emergency protocols for managing public health were developed.

Black water quality alerts – indicating a spillover of wastewater – were removed only after stringent water testing results.

A new regime of stricter water testing was followed before the black alerts were lifted.

Guidelines for recreational water quality require at least two ‘clear samples’ before Auckland Council can confirm a water contamination event is over.

Following the storm event however, it was decided three clear samples would be needed before water quality could be reported as normal once more.

A spokesperson for Auckland Council said while in recent years Aucklanders had seen more frequent ‘black water quality pins’ on the Safeswim website indicating a confirmed discharge of wastewater, it didn’t necessarily indicate a worsening of water quality.

Instead it could reflect the increase in the number and reliability of real-time sensors on the wastewater network close to beaches, and improved communication and teamwork between staff within and across Watercare and Auckland Council.

But events like the Ōrākei main sewer collapse last September temporarily returned the plague of black alerts to the Waitematā Harbour.

There are a handful of beaches where Auckland Council says it’s still not safe to go back in the water, with long-term warnings in place due to evidence of very poor water quality.

The no-go spots are centred on the inner Waitematā and the northern shore of Manukau Harbour – Coxs Bay and Meola Reef in Westmere, Fosters Bay near Huia, Green Bay and Lynfield Cove in Whau and Wood Bay near Titirangi.

Lynfield Cove received its long-term alert at the end of 2022.

Sixty-one samples were taken from the site after the local board identified it as a popular swimming spot in 2019. 

But 34 of these samples exceeded government safety guidelines, which require councils to notify the public when levels of faecal bacteria indicate more than one in 50 people would likely become ill after putting their head under water.

This failure of 56 percent was well above the commonly accepted 10 percent frequency frequently used internationally as a threshold for poor water quality alerts.

Faeces from humans, dogs and birds were found in investigations at the cove, likely due to streams and stormwater outlets discharging nearby.

Other beaches spent much of last summer in an unsafe state due to a raft of reasons – proximity to wastewater outlets, currents and harbour location – but have no long-term warning in place.

The lowest scoring, still-swimmable beach was Home Bay (near Herne Bay), which was unsafe to swim for 54.7 percent of last summer.

Joining it at the bottom of the list of swimmable beaches is the highly-popular Herne Bay, which was unsafe 54.5 percent of the time.

Meanwhile, open ocean-facing beaches further from the city tended to fare better.

The top spot is occupied by three out-of-town spots, all within or near to marine reserves: Anchor Bay, Goat Island and Tawharanui.

More surprising is the fact that the centrally-situated Devonport got one of the cleanest bills of health in the region, with compliance 93.8 percent of the time.

For the most part, however, the trend seems to be that the closer to Auckland’s central isthmus, the more likely that a beach spent a significant length of time in a polluted and unsafe state last summer.

The figures show the unsafest swimming conditions the region has seen since data has been formally recorded – coinciding with record levels of rainfall:

Water testing conducted through the Safeswim programme is used to guide where new infrastructure should go. However, in a workshop with Auckland’s councillors last year, Safeswim staff stressed there is often a large time lag between identifying water quality issues and resolving them.

According to Safeswim there is a higher risk of poor water quality at beaches:

• after rain – especially heavy rain
• in or near stormwater outlets and urban streams feeding onto beaches,
• near ageing network infrastructure in the city centre
• in areas where residential growth has put infrastructure under stress
• in areas serviced by ageing onsite septic systems.