When you think about threats to the Great Barrier Reef, coral bleaching due to climate change would likely be first.

But the world’s largest reef system faces many threats. One surprisingly large threat is poor water quality. When sediment is washed off farms, cities and bushland into rivers, it can be transported kilometres offshore. If there’s too much, it can smother corals and seagrass meadows. Fertiliser and pesticide residue can make things worse.

Unlike the global problem of climate change, water quality is a threat Australia can directly address. The issue has been repeatedly flagged by UNESCO, the United Nations body responsible for World Heritage areas such as the reef. In its latest draft decision – the fourth since 2023 – water quality remains a major issue, alongside climate change.

The draft decision notes “with utmost concern, the continuing negative impacts on hard coral cover across the Reef” and asks the Australian government to report on the damage done by coral bleaching in 2024–25 as well as poor water quality, unsustainable fishing practices and poorly managed uses of coastal land. The draft decision also requests an assessment of the impacts caused by dumping sediments from dredging in coastal waters.

In April, the Queensland and federal governments released a revised strategy to improve water quality. Previous plans have talked the talk but failed to deliver.

The new strategy is also likely to disappoint. It relies on broad vision statements without clear responsibilities, an adequate budget or realistic actions.

Water pollution is the biggest local threat

For years, one of the biggest local threats........

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