The Manukau has been treated as the backside of Auckland for decades. Power pylons were routed around the edges of the growing suburbs until they were finally pushed out into the harbour itself. Then housing expanded under the terrestrial pylons.
Onehunga was Auckland’s main port until ships became too large to cross the bar. Auckland has finally started to interact well with the Waitemata Harbour edge. Similar development at Onehunga is still in the planning stages.
The Mangere Waste Water Treatment Plant is the biggest insult, though. Swimming has been banned at Laingholm and Wood Bay with permanent signs erected. Auckland Council has ceased routine monitoring of water quality at these beaches.
Green Bay registered 24,200 enterococci per 100ml of water – 173 times the maximum safe level for swimming of 140. That was back on 16 November 2016. Up until January 2017 it had exceeded safe levels 4 weeks out of 10.
The Mangere Waste Water Treatment Plant reached capacity, and semi-treated effluent bypassed full treatment 20-22 times each year after heavy rain over the last decade. “On June 29-30 last year about 124 Olympic-sized swimming pools of partially-treated waste water was discharged into the Manukau just across the harbour from the beaches at Laingholm, Wood Bay and Green Bay,” said waste water biologist Gemma Tolich Allen.*
After publicity about low water quality in both harbours, Phil Goff called for advancing the construction of the huge 5m diameter “Central Interceptor” pipe across Auckland to the Mangere Plant. This $1 billion project has been shuffled backwards over the last decade as councillors scramble to find money for other projects.
With Auckland’s growing population, the Central Interceptor will be able to divert sewage from spills into the Waitemata and deliver more waste faster to the Mangere Plant.
Will the Mangere Waste Water Treatment Plant be expanded fast enough to cope with this increase? And why is “treated” waste still discharged into our Manukau Harbour instead of the Tasman Sea?
*NZ Herald, February 2017