Land-based run-off pressure on the Great Barrier Reef World Heritage Area

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Key finding

Although declining marine water quality is one of the most significant threats to the Great Barrier Reef, agricultural practices are improving resulting in reductions in land-based run-off entering the region and the resulting impact on the Reef's outstanding universal value (OUV).

Great Barrier Reef (information applies statewide, map locations are for reference only)

There are a range of land uses within reef catchments and on islands. Catchment land management practices influence the quality and amount of freshwater that flows into the reef lagoon, including components known to affect the reef's ecosystem—nutrients, sediments, pesticides and other pollutants such as heavy metals and marine debris.

Inshore areas are particularly at risk from poor water quality especially in central and southern areas.

Sediments and nutrients continue to enter the Great Barrier Reef ecosystem at greatly enhanced levels compared to those prior to European settlement, resulting in increased exposure in inshore areas, as well as further offshore. Modelling conducted in 2013 estimates at 12,114kg of herbicides are introduced into the Great Barrier Reef Region each year from diffuse source agricultural run-off.

Declining marine water quality, influenced by land-based run-off, is one of the most significant threats to the long-term health and resilience of the Great Barrier Reef.

Marine debris, from onshore and offshore sources, continues to affect the ecosystem and is of particular concern for species of conservation concern. Many of the region’s heritage values, including its outstanding universal value, are vulnerable through the ecosystem effects of land-based run-off, especially in central and southern inshore areas. Water quality declines and marine debris are likely to be diminishing Reef’s natural beauty.

More information:

Indicator: Land-based run-off

Direct use pressure on the Great Barrier Reef World Heritage Area as reported in the Great Barrier Reef Outlook Report 2014.

Condition dial — grade 2 (Poor) on a 1–4 scale

See also: World assessment summary.