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Stricter regulations on sewage discharge from vessels have been imposed by several regional councils to protect specific areas including ports, sheltered waters and fisheries resources within their regions. If vessels wish to discharge sewage within 500 metres of land or within sheltered waters, they must first contact local regional council to ensure they meet the local guidelines.
Under Part 160 of the Marine Protection Rules the discharge of sewage from ships greater than 200 tonnes or carrying more than 10 people is restricted in the Antarctica Treaty Area.
Given the large volume of sewage that may be produced on large vessels, it is considered that even after treatment discharge of this waste may cause environmental impacts in shallow or confined waters. Operators of large vessels are therefore strongly encouraged not to discharge any sewage within 500 metres of the nearest land, marine reserve or marine farm.
To further minimise any impacts, sewage from holding tanks should only be discharged at a moderate rate while the vessel is underway.
It is important that on-board sewage treatment systems are operated and maintained so that they function well. This will ensure that the resulting effluent is of a suitable quality for discharge without causing unacceptable environmental harm.
High levels of residual chlorine or other chemicals used to reduce bacterial numbers in effluent can also negatively impact on marine species, and dosing levels should be managed carefully.
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