Water quality in the Great Barrier Reef

Good water quality is the reason why the Great Barrier Reef is one of the most beautiful, diverse and complex ecosystems in the world. Reefs grow best in waters that have naturally low concentrations of nutrients (nitrogen and phosphorus) and sediments.

Increased use of nutrients, pesticides and other pollutants on the land result in more of these entering waterways and the Great Barrier Reef. The resulting decline in water quality can affect corals, seagrass and other important habitats as well as the marine animals they support, while also having a detrimental affect on tourism and fishing industries.

Land and water connections

The Great Barrier Reef receives the run-off from 35 basins which drain 424,000km2 of coastal Queensland. River discharges are the single biggest source of nutrients to the inshore areas of the Great Barrier Reef World Heritage Area.

Over the past 150 years sediment inflow into the Great Barrier Reef has increased four to five times, and five to ten fold for some catchments.

Catchment run-off and associated water quality is identified as the second most significant pressure on the Great Barrier Reef and is expected to have significant compounding effects with climate change.

Coastal areas

Coastal ecosystems play a vital role for the Great Barrier Reef. Not only do they contribute to the quality of water entering the Reef, they are a vital link between the land, freshwater and marine environments.

Extensive areas of habitats that support the Great Barrier Reef ecosystem have been infilled, modified or cleared. This loss of coastal habitats is concerning as they are important feeding and breeding grounds for marine species and sediments traps and nutrient filters for water entering the Great Barrier Reef.

Coastal development is affecting coastal habitats that support the Great Barrier Reef. Human population increases within the Great Barrier Reef catchment are projected to be nearly two per cent per annum. This will place greater pressure on the ecosystem and increase the use of the Great Barrier Reef Region.

Improving water quality

The Great Barrier Reef Marine Park Authority (GBRMPA) is a partner in the Australian and Queensland government's commitment to the Reef Water Quality Protection Plan (Reef Plan). This joint plan of action aims to halt and reverse the decline in the quality of water flowing into the Great Barrier Reef.

Part of the GBRMPA's commitment to Reef Plan is the management of the Reef Rescue Marine Monitoring Program which monitors the long-term health of key marine ecosystems and the condition of water quality in the inshore Reef lagoon.

The GBRMPA has prepared Water Quality Guidelines for the Great Barrier Reef Marine Park. The guidelines identify 'trigger' levels for managers to take action if conditions exceed them.

Reef Guardians,an initiative of the GBRMPA, is a voluntary stewardship program made up of schools, councils, fishers and farmers, and is proving that by working together today we can all contribute to a healthier Reef for tomorrow.

The community-based initiative showcases the environmental actions being undertaken within coastal communities and industries both in the Great Barrier Reef catchment and in the Marine Park.

Check out this video to hear how local farmers are helping to reduce run off and improve water quality flowing into the Great Barrier Reef catchment.

  • Free zoning app

    Zoning maps

    If you're heading out on the water, download and use the free zoning app so you know where you can go and what you can do.

  • Important milestone

    40 years anniversary

    We're delighted to celebrate the 40 years of the managing the Great Barrier Reef.

  • Visit the Reef

    fish on reef

    Visit our Great Barrier Reef and discover its amazing animals, plants, and habitats.

  • What you can do

    purple coral

    Everyone has a role to play in protecting our Great Barrier Reef. Find out what you can do to help protect this great Australian icon.

  • Report marine strandings


    If you see sick, dead or stranded marine animals please call RSPCA QLD 1300 ANIMAL (1300 264 625)

  • Climate Change and the Great Barrier Reef

    Climate Change and the Great Barrier Reef vulnerability assessment cover image

    A Vulnerability Assessment: of the issues that could have far-reaching consequences for the Great Barrier Reef.

  • Current Conditions

    Current Conditions logo promo image

    Current Conditions: Environmental and climatic forecasts for the Great Barrier Reef

  • Reef Guardians Improving the outlook

    reef guardians

    The Great Barrier Reef is under pressure. Many people, including Reef Guardians, are making a difference.