Total suspended solids, nutrient and pesticide loads (2013–2014) for rivers that discharge to the Great Barrier Reef

A Garzon-Garcia, Rohan Wallace, Rae Huggins, Ryan DR Turner, Rachael Smith, David Orr, Ben Ferguson, Richard Gardiner, Belinda Thomson, Michael Warne

Research output: Book/ReportOther report

27 Downloads (Pure)

Abstract

Poor water quality caused by diffuse pollutants being exported from catchments to the Great Barrier Reef lagoon is an important threat to the health and resilience of the Reef. Sediment, nutrient and pesticides leaving agricultural land have been identified as the most significant cause of poor water quality entering the Reef lagoon (Brodie et al. 2013a). The Reef Water Quality Protection Plan 2013 (Reef Plan 2013), which this report relates to, has the long term goal of ‘ensuring that by 2020 the quality of water entering the reef from broad scale land use has no detrimental effect on the health and resilience of the Great Barrier Reef’ (DPC 2013a).
Reef Plan 2013 established new land and catchment management targets and water quality targets that are measured against baseline conditions outlined in the preceding Reef Water Quality Protection Plan 2009. These reduction targets, to be achieved in 2018, are: at least a 20 per cent reduction in anthropogenic end-of-catchment loads of sediment and particulate nutrients; at least a 50 per cent reduction in anthropogenic end-of-catchment dissolved inorganic nitrogen loads; and at least a 60 per cent reduction in end-of-catchment pesticide loads.
Progress towards the Reef Plan 2013 water quality targets is measured based on modelled values (Waters et al. 2014) through the Paddock to Reef Integrated Monitoring, Modelling and Reporting Program (Paddock to Reef Program). The Paddock to Reef Program includes catchment scale water quality monitoring of pollutant loads entering the Great Barrier Reef lagoon which is implemented through the Great Barrier Reef Catchment Loads Monitoring Program.
Under Reef Plan 2013, pollutant loads are calculated annually by the Great Barrier Reef Catchment Loads Monitoring Program in the following natural resource management regions and priority catchments:
 Cape York region – Normanby catchment
 Wet Tropics region – Barron, Mulgrave-Russell, Johnstone, Tully and Herbert catchments
 Burdekin region – Burdekin and Haughton catchments
 Mackay Whitsunday region – O’Connell, Pioneer and Plane catchments
 Fitzroy region – Fitzroy catchment
 Burnett Mary region – Burnett and Mary catchments.
This report presents annual loads calculated using monitoring data (monitored annual loads) and yields of pollutants based on monitoring data from the 2013–2014 monitoring year (i.e. 1 July 2013 to 30 June 2014). The data made available through the Great Barrier Reef Catchment Loads Monitoring Program provides a foundation to validate the catchment models used to monitor progress against Reef Plan 2013 water quality targets and thus assist in the effective management of Queensland and Australian natural resources.
During the 2013–2014 monitoring year, 12 end-of-system sites and 13 sub-catchment sites were monitored for total suspended solids and nutrients. Pesticides were monitored at 10 end-of-system sites and five sub-catchment sites. This is the first year that monitored annual loads have been reported for the Haughton, O’Connell and Mary rivers and Tinana Creek in the Mary catchment, and that event loads have been reported for the Mulgrave-Russell catchment. For the first time three tidally influenced sites on the Russell, Mulgrave and O’Connell rivers were monitored.
Total annual rainfall was generally above average in the monitored catchment in the Cape York region and average in all monitored catchments of the Wet Tropics region. In the Burdekin region, all monitored catchments received average to very much below average rainfall, and average rainfall was received across monitored catchments in the Mackay Whitsunday region. Rainfall across the monitored catchments of the Fitzroy region was generally below average to very much below average, and very much below average across most of the Burnett Mary region.
Reflecting the below average rainfall in the central and southern regions, annual discharge was below the long term mean in the majority of monitored rivers, and considerably below the long term mean discharge in the Burdekin, O’Connell, Fitzroy, Burnett and Mary rivers and Sandy Creek in the Plane catchment. Discharge in the Burdekin and Fitzroy rivers during the 2013–2014 monitoring year was the lowest monitored since commencement of the Great Barrier Reef Catchment Loads Monitoring Program in 2006. River discharge in the Mulgrave, Russell, North and South Johnstone, Tully and Herbert rivers was above their long term mean. Rainfall associated with severe Tropical Cyclone Ita resulted in moderate to major flooding in the Normanby, Barron, Mulgrave, Herbert and Haughton rivers and contributed a significant portion of the total annual discharge in the 2013–2014 monitoring year.
The monitored catchments generated approximately 1.4 million tonnes of total suspended solids, 12,000 tonnes of nitrogen and 1800 tonnes of phosphorus. Three catchments generated approximately 50 per cent of the combined load of total suspended solids and nutrients. The Herbert catchment generated the largest total suspended solids and nutrient loads, with the exception of dissolved organic nitrogen and dissolved inorganic phosphorus in which the Normanby and Fitzroy catchments generated the largest loads respectively, and the Johnstone (North and South Johnstone together) catchment which generated the largest loads of total phosphorus and particulate phosphorus. The Tully catchment made substantial contributions of most nitrogen fractions, the Burdekin catchment of total suspended solids and dissolved inorganic phosphorus, and the Fitzroy catchment of ammonium nitrogen and dissolved organic nitrogen.
The Burdekin and Fitzroy catchments typically contribute the largest annual loads of total suspended solids and nutrients, however in the 2013–2014 monitoring year the loads generated by these catchments was the lowest reported by this Program since 2006 and consistent with the record low discharge during this period.
A measure of the supply of pollutants from catchments is the yield (the load divided by the monitored surface area of the catchment). This metric allows a comparison of the rate of pollutant delivery between catchments standardised by area. The highest monitored yields of total suspended solids, total nitrogen, particulate nitrogen, total phosphorus and particulate phosphours occurred in the Johnstone (North and South Johnstone, together) catchment. The Tully catchment produced high yields of total suspended solids and all nutrient analytes, the O’Connell catchment produced high yields of ammonium nitrogen and Sandy Creek in the Plane catchment produced high yields of dissolved inorganic phosphorus. The lowest monitored yields of all total suspended solids and nutrient analytes generally occurred in the larger catchments of the Burnett, Burdekin and Fitzroy rivers.
The total monitored annual load of photosystem II inhibiting herbicides1 exported past the monitoring sites were (from largest to smallest): 930 kg of total atrazine; 890 kg of total diuron; 230 kg of hexazinone; 160 kg of tebuthiuron; and 11 kg of ametryn. The combined toxicity-based load (toxic load2) of all monitored sites was 980 kg TEqdiuron, with total diuron accounting for 890 kg TEqdiuron. Five catchments (the Tully, Pioneer and Herbert catchments, Sandy Creek in the Plane catchment and Barratta Creek in the Haughton catchment) accounted for 90 per cent of the combined annual toxic load.
The largest monitored land use yield (the load divided by the total surface area of land uses where the pesticide is registered for use) of ametryn was in Sandy Creek in the Plane catchment; total diuron, total atrazine and hexazinone in the Tully catchment, and tebuthiuron in the O’Connell catchment.
This is the fifth technical report to be released by the Great Barrier Reef Catchment Loads Monitoring Program and the first under Reef Plan 2013. The Paddock to Reef Integrated Monitoring, Modelling and Reporting Program was reviewed in 2013. This review resulted in decommissioning several sub-catchment sites and establishment of new end-of-system sites to provide data for previously unmonitored catchments and improve spatial alignment of the Great Barrier Reef Catchment Loads Monitoring Program and the Marine Monitoring Program. The underlying methods of the Great Barrier Catchment Loads Monitoring Program have not had major changes over the years to maintain consistency in the reported data. During the 2013–2014 monitoring year, a key improvement to the analysis of the water quality data was the introduction of the toxic load concept to report pesticide loads. The calculation of total diuron from its metabolites was also introduced.
Original languageEnglish
Place of PublicationBrisbane, Australia
PublisherDepartment of Science, Information Technology and Innovation
Number of pages108
Publication statusPublished - 2016

Keywords

  • Loads
  • Great Barrier Reef
  • Pollutant Loads
  • Suspended Sediment
  • Nutrients
  • Pesticides

Fingerprint Dive into the research topics of 'Total suspended solids, nutrient and pesticide loads (2013–2014) for rivers that discharge to the Great Barrier Reef'. Together they form a unique fingerprint.

  • Cite this

    Garzon-Garcia, A., Wallace, R., Huggins, R., Turner, R. DR., Smith, R., Orr, D., ... Warne, M. (2016). Total suspended solids, nutrient and pesticide loads (2013–2014) for rivers that discharge to the Great Barrier Reef. Brisbane, Australia: Department of Science, Information Technology and Innovation.