Agricultural Run-off

Run-off from agricultural land is the largest source of pollutants impacting the Great Barrier Reef.

Different land uses are associated with different water quality issues:

  • Rangeland grazing generates high levels of sediment, and nutrients that are attached to sediment.
  • Dryland cropping can generate large amounts of sediment (but occurs over a smaller area).
  • Urban areas and mining also generate large amounts of sediment.
  • Agricultural use of fertilisers is linked to levels of dissolved nutrients in waterways.
  • Most of the pesticides of greatest concern in the Great Barrier Reef are linked to sugar cane cultivation in coastal catchments, but the herbicide tebuthiuron, also of concern, comes from rangeland grazing areas.

Therefore, the water quality issues in any region will be a reflection of the land use and land management practices of that area.

As a large catchment dominated by grazing, the Fitzroy Basin delivers large amounts of sediment, and nutrients that are attached to the sediment, to the Reef. The amount of sediment coming from the Fitzroy Basin is estimated to be about seven times natural levels. Because of its size, the Fitzroy Basin delivers much larger amounts of pollutants than the smaller, coastal catchments such as the Boyne and Calliope. Tebuthiuron is the main herbicide of concern in this region.

Select the different pollutants from the list on the upper left to discover more about why they are a threat to the Reef.

Click on the thumbnails below for a larger image