Around 11 billion litres of part-treated sewage is dumped in Darwin Harbour each year. This is disgraceful.
Plus dozens of stormwater drains dump pollutants into the Harbour, such as dog fertiliser from lawns and golf courses, human and animal waste, and litter.
This unacceptable pollution puts risks our beautiful harbour and the marine wildlife that live there, the health of swimmers and yachties, and the fish and mud crabs many Territorians and visitors love to eat.
Regarding sewage pollution, the Environment Centre NT has spent many years exposing the stupidity of dumping so much poorly treated sewage in the harbour. We’ve been pushing Power and Water Corporation and Territory politicians to commit the hundreds of millions of dollars required to upgrade the sewage plants to at least tertiary treatments standards and commence large scale wastewater reuse.
For too many years, the harbour has been used in essence as a communal toilet for greater Darwin.
In 2010 and 2011, high bacterial levels caused by pollution in the harbour closed several beaches to swimmers for weeks at a time. While poor catchment management and other factors are likely to be key drivers of the bacterial contamination, lessons from other harbours around the world indicates a strong likelihood that the year-round sewage pollution by Power and Water Corporation to be a key contributor as well.
Most of the sewage treatment plants are owned by the taxpayer and operated by Power and Water Corporation, which is owned by the Territory Government.
Water quality monitoring by the Environment Department identifies the worst harbour pollution occurs in Buffalo Creek, which receives poorly treated sewage from the Leanyer Waste Water Treatment Plant.
While the Larrakeyah Outfall (the infamous ‘poo-shooter’) is being shut down and the sewage piped to the Ludmilla Waste Water Treatment Plant, it will only receive ‘enhanced primary’ treatment. This means the harbour will be polluted with around one-and-a-half billion litres of poorly treated sewage each year. During very heavy rainfall, almost raw sewage flows directly into Ludmilla Creek.
Power and Water Corporation have no plans to upgrade Ludmilla sewage plant for at least 20 years. Given the plant has no room for building large settling ponds, and that it at risk of increasing inundation from rising sea levels and storm surges due to climate change, the best option is probably to shot down the plant and pipe the sewage to another sewage plant that does provide treatment to at least tertiary standards and large scale reuse.
For too many years the Environment Department simply issued pollution licences to Power and Water Corporation that allowed them to pollute the harbour. They should impose extremely tough water quality standards on all new pollution licences that they issue to the utility, and take court action for breaches.
The solution is simple, if costly. The half dozen sewage plants owned by Power and Water Corporation should be brought up to tertiary treatment standards, or shut down. Instead of treating the sewage as waste water, it should be seen as a resource that should be treated to high standards and reused around Darwin to water parks and gardens, in industry, and to irrigate horticulture.
Options for increasing the funds and staff available to Power and Water Corporation include allowing them to raise sewage rates to fully recover the costs of the upgrade and reuse systems within the next decade (including by allowing sewage and water rates to be set by the independent Utilities Commissioner), seeking infrastructure grants from the Australian Government, and supporting new markets for selling treated wastewater for reuse.