The health of Tasmania’s coastal marine environment is impacted by land-based activities including agriculture run-off, ageing septic systems, sewage outfalls, heavy industry, boatyards, cruise ships and other pollution from coastal industry and development.
Hobart’s waste water from both the city and heavy industry went largely untreated until the 1980’s, and often contained pathogens, nutrients, arsenic, PCB’s (polychlorinated biphenyls), heavy metals, acids and other compounds. Heavy metals still persist in the sediment of the Derwent Estuary and PCB’s in the flesh of both filter feeders and fish. The Derwent Estuary Program has made tremendous progress in improving the health of the waterway. Unfortunately, the expansion of salmon farming within Storm Bay comes with the risk of re-mobilising these heavy metals.
Boat slipways, boatyards and marinas are a source of hazardous liquid and solid waste, oils and paint chips which often contain toxic heavy metals.
In early 2023, Rights to Information documents showed that the ageing Macquarie Point sewage treatment plant had been in regular breach of its EPA commitments and leaking chemicals into the Derwent Estuary, creating a “high risk” of toxicity. The debate over whether this plant will be moved further up-river to a newer facility at Self’s Point has not been resolved.