In 2015, in response to visible signs of pollution and odours, Panuku Development Auckland, along with other Auckland Council teams, began to monitor water quality in the bay and found that it suffered from increased concentrations of bacteria, and heavy metal contamination.
In 2016 a working group was established enabling Auckland Council’s Healthy Waters team, and the CCOs Watercare, Panuku Development Auckland and Auckland Transport, to bring about improvements in water quality more quickly.
Causes of pollution
Following a period of investigation and water testing, the primary cause of water quality issues in St Marys Bay was identified as the combined stormwater and wastewater network used by properties in the adjacent suburb. This type of network dates back to the early twentieth century, and carries both wastewater and stormwater in the same pipes and it regularly overflows and releases stormwater and sewage into the bay.
Other contributors are likely to be:
- Vessels discharging waste illegally: While Westhaven Marina is a no discharge zone and this is actively enforced, it’s possible that boats do from time to time discharge untreated sewage into the marina even though sewage removal facilities are available.
- Antifouling paint: More environmentally friendly antifoul products and alternatives to antifoul are being developed and coming onto the market, and improved facilities for applying and removing antifoul are also available.
- Stormwater run off from roads and other surfaces contains heavy metals, sediment and solids, and the marina’s carparks are now fitted with a number of devices to clean and filter this water.
- The large bird population living within Westhaven that may slightly elevate bacterial levels, as will dogs using St Marys Bay Beach, and even polluted water entering the marina from other locations in the harbour.
Health & Safety
If you are using St Marys Bay for watersports, please check the SwimSafe website through summer, and be cautious about coming into contact with water for 48 hours after heavy rain.
Short, medium and long term solutions
While planned solutions are on the long term horizon, the project team are seeking to bring forwards improved water quality outcomes for St Marys Bay.
Solutions that were immediately implemented included:
- the introduction of SafeSwim monitoring in the bay to better inform users of the bay about water quality
- the installation of 100 TetraTraps in the adjacent residential area
- installation of and an automatic sensor to enable operations staff to quickly resolve any dry weather overflows from the network
- Panuku Development Auckland as managers of Westhaven Marina took a hard line on any boats found to have illegally discharged sewage into the bay, along with a range of ongoing environmental initiatives.