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Catchment pollutant loads

The pollutant loads at the end of the catchment come from modelling, validated by monitoring, to remove the effect of a variable climate from year to year.

The pollutant loads leaving catchments and entering the reef vary significantly from year to year, mainly due to differences in annual rainfall. Catchment modelling has been used to correct the annual pollutant loads for climate variability and estimate the long term annual load reductions due to the adoption of improved management practices. Progress towards load reduction targets is modelled using well documented methods and assumptions, and long term water quality monitoring is used to validate these modelled results. Progress is measured in terms of the reduction in loads due to agriculture (termed ‘anthropogenic load' in this context).

The catchment loads targets are ambitious measures designed to be met in 2013 for nutrients and pesticides and 2020 for sediment. The bar indicators below show the one-year reduction in load as at June 2010. This period covers only the first year of Reef Plan implementation. More progress will be evident in the third and subsequent Report Cards. This result is a very good outcome as it demonstrates the program is arresting and reversing the loads into the reef.

The load reductions do not include all activities undertaken during the reporting period and are, therefore, considered an underestimate of total progress. For example, land management changes in the horticulture and dairy industries and parts of the grains industry have not been modelled at this time. Changes in riparian management also could not be modelled due to the lack of data.

Great Barrier Reef

Nitrogen

Target: A minimum 50% reduction in nitrogen load at the end-of-catchments by 2013.

Result: Moderate progress

Graph showing Great Barrier Reef nitrogen load.

  • The estimated annual average total nitrogen load leaving catchments reduced by 4% (641t).
  • The greatest per cent load reduction (6%) was in the Burdekin and Burnett Mary regions with 346t and 91t, respectively.
  • The total nitrogen load leaving the Great Barrier Reef catchments was an estimated 36,843t per year, double the pre-development load.

Phosphorus

Target: A minimum 50% reduction in phosphorus load at the end-of-catchments by 2013.

Result: Moderate progress

Graph showing Great Barrier Reef phosphorus load.

  • The estimated annual average total phosphorus load leaving catchments reduced by 2% (83t).
  • The greatest per cent load reduction was from the Burdekin region with 3% (35t), the majority being particulate phosphorus.
  • The total phosphorus load leaving the Great Barrier Reef catchments was an estimated 6312t per year, which is two and half times greater than the pre-development load.

Sediment

Target: A minimum 20% reduction in sediment load at the end-of-catchments by 2020.

Result: Good progress

Graph showing Great Barrier Reef sediment load

  • The estimated annual average suspended sediment load leaving catchments reduced by 2% (105,000t).
  • The greatest per cent load reduction was in the Mackay Whitsunday region.
  • The average annual total suspended sediment load leaving the Great Barrier Reef catchments was an estimated 8,850,000t per year, a threefold increase on the pre-development load. The regions contributing the highest total suspended sediment loads were the two largest catchments which are dominated by grazing - the Burdekin (4,104,000t per year) and the Fitzroy (2,034,000t per year).

Pesticides

Target: A minimum 50% reduction in pesticide load at the end-of-catchments by 2013

Result: Good progress

Graph showing Great Barrier Reef pesticide load.

  • The estimated annual average pesticide load leaving catchments reduced by 8% (1254kg).
  • The greatest per cent load reductions were from the Mackay Whitsunday and Burnett Mary regions with 18% (376kg) and 14% (219kg), respectively.
  • Agricultural lands are a key source of pesticide runoff, particularly cane lands. The total load of photosystem II pesticides leaving the Great Barrier Reef catchments was 16,692kg

Graph data (.csv, 1 KB)

Cape York

The pollutant loads at the end of the catchment come from modelling, validated by monitoring, to remove the effect of a variable climate from year to year.

Changes in riparian management could not be modelled due to the lack of data. Load reductions are estimated for the Normanby catchment only.

Nitrogen

Graph showing Cape York nitrogen load.

The estimated annual average total nitrogen load leaving the Normanby catchment reduced by 2% (7t).

Phosphorus

Graph showing Cape York phosphorus load.

The estimated annual average total phosphorus load leaving the Normanby catchment reduced by 2% (3t).

Pesticides

Graph showing Cape York pesticide load

There were no load reductions for pesticides in the Normanby catchment.

 Sediment

Graph showing Cape York sediment load.

The estimated annual average suspended sediment load leaving the Normanby catchment reduced by 1% (3000t).

Graph data (.csv, 1 KB)

Wet Tropics

The pollutant loads at the end of the catchment come from modelling, validated by monitoring, to remove the effect of a variable climate from year to year.

Land management changes in the horticulture and dairy industries have not been modelled. Changes in riparian management also could not be modelled due to the lack of data.

Nitrogen

Graph showing Wet Tropics nitrogen load

The estimated annual average total nitrogen load leaving catchments reduced by 2% (111t).

Phosphorus

Graph showing Wet Tropics phosphorus load

The estimated annual average total phosphorus load leaving catchments reduced by 2% (20t).

Pesticides

Graph showing Wet Tropics pesticide load

The estimated annual average pesticide load leaving catchments reduced by 4% (434kg).

Sediment

Graph showing Wet Tropics sediment load.

The estimated annual average suspended sediment load leaving catchments reduced by 1% (10,000t).

Graph data (.csv, 1 KB)

Burdekin

The pollutant loads at the end of the catchment come from modelling, validated by monitoring, to remove the effect of a variable climate from year to year.

Land management changes in the horticulture industry have not been modelled. Changes in riparian management also could not be modelled due to the lack of data.

Nitrogen

Burdekin nitrogen load

The estimated annual average total nitrogen load leaving catchments reduced by 6% (346t).

Phosphorus

Graph showing Burdekin phosphorus load

The estimated annual average total phosphorus load leaving catchments reduced by 3% (35t).

Pesticides

Graph showing Burdekin pesticide load

The estimated annual average pesticide load leaving catchments reduced by 10% (225kg).

Sediment

Graph showing Burdekin sediment load

The estimated annual average suspended sediment load leaving catchments reduced by 2% (61,000t).

Graph data (.csv, 1 KB)

Mackay Whitsunday

The pollutant loads at the end of the catchment come from modelling, validated by monitoring, to remove the effect of a variable climate from year to year.

Land management changes in the horticulture industry have not been modelled. Changes in riparian management also could not be modelled due to the lack of data.

Nitrogen

The estimated annual average total nitrogen load leaving catchments reduced by 4% (76t).

Phosphorus

The estimated annual average total phosphorus load leaving catchments reduced by 1% (5t).

Pesticides

The estimated annual average pesticide load, largely from sugarcane cultivation, leaving catchments reduced by 18% (376kg).

Sediment

The estimated annual average suspended sediment load leaving catchments reduced by 3% (11,000t).

Graph data (.csv, 1 KB)

Fitzroy

The pollutant loads at the end of the catchment come from modelling, validated by monitoring, to remove the effect of a variable climate from year to year.

Land management changes in the horticulture and grains industries have not been modelled. Changes in riparian management also could not be modelled due to the lack of data.

Nitrogen

Fitroy nitrogen load

The estimated annual average total nitrogen load leaving catchments reduced by 0.4% (9t). This does not include nitrogen reductions from improved cropping practices.

Phosphorus

Fitzroy phosphorus load

The estimated annual average total phosphorus load leaving catchments reduced by 1% (11t).

Pesticides

Fitroy pesticide load

There were no load reductions for pesticides in the Fitzroy region. This does not include pesticide reductions from improved grazing practices.

Sediment

Fitroy sediment load

The estimated annual average suspended sediment load leaving catchments reduced by 1% (17,000t).

Graph data (.csv, 1 KB)

Burnett Mary

The pollutant loads at the end of the catchment come from modelling, validated by monitoring, to remove the effect of a variable climate from year to year.

Land management changes in the horticulture industry have not been modelled. Changes in riparian management also could not be modelled due to the lack of data.

Nitrogen

Graph showing Burnett Mary nitrogen load.

The estimated annual average total nitrogen load leaving catchments reduced by 6% (91t).

Phosphorus

Graph showing Burnett Mary phosphorus load.

The estimated annual average total phosphorus load leaving catchments reduced by 3% (9t).

Pesticides

Graph showing Burnett Mary pesticide load.

The estimated annual average pesticide load leaving catchments reduced by 14% (219kg).

Sediment

Burnett Mary sediment load

The estimated annual average suspended sediment load leaving catchments reduced by 1% (4000t).

Graph data (.csv, 1 KB)

Last updated:
27 August, 2014
Last reviewed:
8 July, 2013

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