Sewage discharges into the ocean only happen during heavy rainfalls when sometimes the amount of sewage coming to the plant exceeds the capacity for the secondary stage of the treatment process. Discharges occur approximately 1.8km from shore.
Map of sewage discharges from Moa Point (45KB PDF)
Environmental effects
In 2003, Wellington City Council commissioned the Cawthron Institute to investigate the potential environmental effects of these occasional mixed discharges. The study concluded that these discharges posed minimal risk to public health, shellfish gathering and recreational activities.
In general, Regional Public Health has the following recommendations:
- Do not swim near urban areas for 48 hours after heavy rains, due to the potential health effects of contaminated urban stormwater.
- Do not gather shellfish for consumption at any time from coastal locations near urban areas.
Resource consents
On 11 May 2009, Wellington City Council received consent under the Resource Management Act for these occasional discharges.
Consent only applies when the quantity of wastewater arriving at the Moa Point Treatment Plant exceeds 3,000 litres per second (that is, the plant's capacity for the secondary stage of treatment).
The consent expires on 11 May 2034 when the overall resource consent for discharges from the ocean outfall pipe will expire. At that time, all aspects of the ocean outfall pipe discharges will be reviewed and a new consent sought.
Summary of investigations for Moa Point interim consent application (69KB PDF)
Reporting and monitoring
Under the terms of the consent, the Council must monitor and record the details of any mixed discharge from the Moa Point plant and make these available to the public.
As well as making the information available online, the Council also posts notification signs - one at the Dorrie Leslie boat ramp, four along Lyall Bay beach and one at Tarakena Bay. These signs explain the location and nature of the discharge and the potential risk to public health from bathing or collecting shellfish in the vicinity. These signs remain in place for at least 48 hours after the discharge ends.