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Catchment loads

Modelling of pollutant load reductions is based on reported improvement in management practice systems. Results are an estimate of the annual average reduction in human-caused (anthropogenic) pollutant loads at the end of catchments.

About the indicators

Confidence in catchment loads condition grade - 3 out of 5

The catchment loads modelling program estimates average annual loads of key pollutants (sediment, nutrients and pesticides) for each of the 35 catchments draining to the Great Barrier Reef. It models the anthropogenic baseline load and the change in loads for each subsequent year due to the adoption of improved land management practices. For more information, refer to Why use modelling to measure catchment loads?

Scoring system

A standardised scoring system was developed for each key indicator in the report card. The scoring system is used to access and communicate progress towards the catchment targets using the following categories

Results—colour coding
Very goodGoodModerate
PoorVery poorNo data

Further details on the scoring system (PDF, 596K) for each indicator are outlined in the supporting technical information.

Dissolved inorganic nitrogen

Reduction in annual average dissolved inorganic nitrogen load between 2009 and 2014. Target: 50% by 2018.

Great Barrier Reef 17.0% Poor
Wet Tropics 14.5% Very poor
Burdekin 16.0% Poor
Mackay Whitsunday 24.0% Moderate
Burnett Mary 31.5% Very good

Particulate nitrogen

Reduction in annual average particulate nitrogen load between 2009 and 2014. Target: 20% by 2018.

Great Barrier Reef 11.5% Good
Cape York 8.0% Poor
Wet Tropics 11.5% Good
Burdekin 15.0% Very good
Mackay Whitsunday 11.0% Good
Fitzroy 3.0% Very poor
Burnett Mary 6.0% Very poor

Particulate phosphorus

Reduction in annual average particulate phosphorus load between 2009 and 2014. Target: 20% by 2018.

Great Barrier Reef 14.5% Very good
Cape York 12.0% Very good
Wet Tropics 20.5% Very good
Burdekin 15.5% Very good
Mackay Whitsunday 13.0% Very good
Fitzroy 6.5% Very poor
Burnett Mary 12.0% Very good

Sediment

Reduction in annual average sediment load between 2009 and 2014. Target: 20% by 2018.

Great Barrier Reef 12.0% Very good
Cape York 8.0% Poor
Wet Tropics 13.5% Very good
Burdekin 17.0% Very good
Mackay Whitsunday 9.0% Moderate
Fitzroy 4.5% Very poor
Burnett Mary 3.0% Very poor

Pesticides

Reduction in annual average toxic pesticide load between 2009 and 2014. Target: 60% by 2018.

Great Barrier Reef 30.5% Good
Wet Tropics 28.5% Moderate
Burdekin 20.0% Poor
Mackay Whitsunday 41.0% Very good
Fitzroy 4.0% Very poor
Burnett Mary 33.0% Good

Read the detailed Catchment pollutant loads results (PDF, 800 KB).

Why use modelling to measure pollutant load reductions?

Monitored pollutant loads leaving catchments vary significantly from year-to-year, mainly due to differences in annual rainfall and runoff. Therefore, catchment modelling is used to estimate the long-term annual pollutant load reductions due to the adoption of improved land management practices. This removes the impact of factors such as climate variability. Research suggests time lags to monitor the improvements from land management practice change could range from years for pesticides up to decades for nutrients and sediments, due to the high level of climate variability. The models use measured changes in on ground management and well-documented and accepted methods and assumptions. Long-term water quality monitoring data is used to validate and improve the models, continuously improving confidence in the estimates of water quality over time.

Example of modelled loads for natural (pre-development), human caused (anthropogenic) and the load reduction following investment in improved practices. The pollutant loads targets aim to reduce the anthropogenic load leaving catchments.

Last updated:
17 December, 2015

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