Water Quality

Monitoring of water quality in the Great Barrier Reef (GBR) region is important because of the changes to land use over the last 150 years. There has been extensive land modification for urban infrastructure, agricultural production, tourism and mining on the land adjacent to the GBR. These changes have led to significant increases in pollutant loads in the rivers since the beginning of European settlement. The major sources of pollutants entering the Reef are agricultural activities on the catchments; urban waste, stormwater discharges and discharges of aquaculture waste are locally important sources of pollution to estuarine and marine waters.

Run-off of freshwater from developed catchment during floods carries a complex mix of pollutants such as nutrients, suspended fine sediments and toxic substances including pesticides, herbicides and other artificial chemicals. Recent research has shown that the biodiversity of reefs exposed to land runoff is reduced compared with reefs adjacent to undeveloped catchments.

Habitats on the GBRWHA are frequently disturbed by natural events such as cyclones, coral bleaching, floods and outbreaks of crown-of-thorns starfish. Reefs usually recover from these acute events. One of the greatest concerns is that coastal reefs may be stressed by declining water quality to a point where they cannot recover from a major disturbance.

Although most reefs in the GBR are more than 20 km from the coast and unlikely to be directly influenced by runoff, approximately 750 reefs are within 10 km of the coast in the zone strongly affected by run-off. Coastal reefs at risk are between Port Douglas and Gladstone.

More information about GBR water quality:

• Water Quality
• CRC Reef land use brochure
• Great Barrier Reef Marine Park Authority’s State of the Reef Report (Water quality)

The Queensland Department of Natural Resources, Mines and Energy (NRM&E) continues to monitor stream flow and water quality at about 220 stations in streams along the GBR coast using automatic recorders, with some additional manual water quality sampling three times a year. Suspended sediments transported in streams during floods is monitored in 10 priority rivers.

The Queensland Environment Protection Agency (EPA) maintained a water quality and nutrient monitoring project in rivers and estuaries for several years, but the north Queensland component of the project was completed in 1999-2000. Data currently available from the NRM&E and EPA monitoring programs have only limited use for estimating river exports of suspended solids and nutrients to the Reef.

The Australian Institute of Marine Science (AIMS) in Townsville has monitored turbidity and nutrient concentrations in north Queensland rivers (Normanby, Barron, Johnston, Tully, Burdekin and Fitzroy rivers) . The program was largely completed in 2000. Data from this program, together with stream flow data from the NRM&E gauging stations have been used to estimate river export rates of suspended sediments and nutrients to the Reef, which have been summarized in the Great Barrier Reef Marine Park Authority’s Water Quality Action Plan.

A major water quality program, not covered in this review, is the National Land and Water Resource Audit. This program has assessed surface water quality nationwide using monitoring data collected by State and Territory agencies. As part of the Audit, sediment exports to the Reef have been estimated. These estimates largely correspond with export estimates derived from the monitoring of river water quality by AIMS

Since 1989, AIMS has also monitored water quality in the Great Barrier Reef offshore from Cairns and Tully .

In 2003, the only broad-scale ongoing project on water quality in the GBR region is the long-term chlorophyll a monitoring program, established in 1992 by the Great Barrier Reef Marine Park Authority (GBRMPA) and currently managed by AIMS and the CRC Reef Research Centre. This project includes sampling of water along transects that run from inshore to offshore waters. These transects are strategically placed along the length of the GBR .

Other water quality monitoring projects include analysis by City Councils, Port Authorities and local industries (e.g. Queensland Nickel) of local water quality issues. Volunteer organisations are also monitoring water quality in Queensland rivers e.g. the Waterwatch program coordinated by NRM and in coastal waters of the Woongarra Marine Park .

Despite the concern about inshore water quality in the GBR region in recent years, there are few ongoing long-term studies to collect data that could be used to determine whether water quality is deteriorating or improving in the GBR lagoon in the future.

Improved future water quality monitoring on the GBR catchment as well as in the GBR lagoon are components of the Reef Water Quality Protection Plan, an initiative of the Commonwealth Government and the Queensland State Government to halt and reverse the decline in water quality entering the GBR.

Click Here to explore detailed information about water quality monitoring programs in the monitoring database.