Overview of the BBB catchment

THIS is an overview of the characteristics of the BBB catchment relevant to the design of the Burdekin MIP (BMIP). A Synthesis Report (refer Volume V) provides more detailed information on the BBB catchment. In summary:

  • The BBB catchment covers an area of 11,718 km2, which is 8.3 per cent of the Burdekin River Basin.
  • The dominant land use is grazing (92%). Designated conservation areas, including national park and state forest, exist in the southern ridges of the Broken sub-catchment (8% of total Catchment area). There is significant open-cut mining (coal) operating in the region, particularly around the town of Collinsville.
  • There are 71 grazing properties (either located partially or fully) in the BBB catchment, of which 63 grazing enterprises are more than 2000ha, and of these, five are owned by mining companies (300,000ha) and one by the Indigenous Land Council. Two properties are owned by government (100,000ha).
  • Tenure in the catchment is dominated by leasehold land (73%), with around 16 per cent freehold land.
  • The BBB catchment sits across four regional council areas. A majority of the catchment is within the Whitsunday Regional Council area, with a small proportion of the Bogie sub-catchment in the Burdekin Shire Council area, a small area of the Little Bowen River sub-catchment within the Isaac Regional Council area, and small parts of the Broken River sub-catchment in the Mackay Regional Council area.
  • The BBB catchment includes parts of the Bowen Broken Bogie Geological basin. As at December 2015, there were four operating coal mines in the Pelican Creek and Rosella Creek sub-catchments, and one operating gold mine in the Bogie sub-catchment. There are also seven unidentified operating mines Department of Natural Resources and Mines (DNRM), ‘Mines on line’ accessed, 2015; business.qld.gov.au/industry/mining/mining-online-services/mines-online) and 119 abandoned mines in the catchment.
  • The major population centre is Collinsville/Scottville, with an estimated population of 1,830 people (Queensland Government Statisticians Office, 2016). A sewage treatment plant (<5,000 equivalent persons) services the centre, discharging ~0.33 ML per day of treated wastewater to Pelican Creek. The public water supply is from the Bowen River Weir.
  • The BBB catchment can be divided into seven major sub-catchments including the Bogie River, Bowen River, Broken River, Glenmore Creek, Little Bowen River, Pelican Creek and Rosella Creek. Waterways vary between largely sandy, dry ephemeral creek systems to permanently flowing clearwater rivers and creeks that originate in mountain rainforest.
  • Among the BBB sub-catchments, the modelling indicates that the rate of erosion is particularly high in the Bowen River, Little Bowen, Bogie and Pelican Creek sub-catchments. The estimates for the Broken River sub-catchment are considered to be an overestimate in the model due to limitations in estimating the cover factor in forested areas (C. Dougall, pers. comm.) and should not be ranked as a priority sub-catchment for sediment management.

Scientist Andrew Brooks (left) and Department of Agriculture and Fisheries extension officer bob Shepherd during the design phase of the project

Sub-catchments in the Bowen, Bogie, Broken catchment, the area in which the Landholders Driving Change project operates

Pictured at the Cairns launch of the two Major Integrated Projects are (from left) Exevale Station graziers Darcy and Buster O’Loughlin, then Minister for the Environment Dr Steven Miles, and CEO NQ Dry Tropics Dr Scott Crawford

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Figure 1. Total fine sediment reduction by project type and erosion source. Inset shows the proportion of the total project area for each project type.

These estimates have been calculated using two methods: 

1) The pollutant reduction component of the Alluvium/Great Barrier Reef Foundation (GBRF) investment tool for hillslope and streambank erosion management projects; 

2) The Reef Trust Gully Toolbox method for gully erosion management projects. The LDC Water Quality Report 2020 (Waterhouse et al., 2020) highlights that a number of assumptions underlay these calculations, therefore these figures should be treated as the best available estimate of sediment reductions to date.

Preventing sediment from reaching the Great Barrier Reef

Each wet season sediment is washed into local waterways and out to the Great Barrier Reef (GBR). 

Most sediment is very fine, and can stay suspended for a long time and can travel great distances. Valuable topsoil is lost from production, and increased concentrations on the reef can be harmful to seagrasses and corals. 

Landholders in the BBB have completed 69 on-ground water quality practice changes, and it is estimated that these have contributed a fine sediment reduction of 6,154 tonnes per year from reaching the GBR. 

Of this, approximately half of the sediment savings are attributable to grazing land management changes on hillslopes and streambanks, and the other half as a result of gully remediation treatments across a broad range of scales, as shown in the graphs above. 

The table below also highlights the relatively small area of intervention in the gully management projects compared to the large sediment savings that these can achieve - 60 per cent of the sediment savings over only 4 per cent of the project area.

Table 1. Estimated sediment reductions (tonnes) from projects completed in the LDC Project to date.

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*GLMWW = Grazing Land Management Wire and Water

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*The Exploring New Incentives activity area has provided an opportunity for graziers to adopt improved land management practices through a range of activities. For some of these properties, it was the first time they signed contracts for on-ground works.

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The LDC project monitors four gully sites (represented in this table) with gold standard equipment and analysis, carried out by CSIRO.

Results have been compiled in a preliminary report from Bartley et al (2020), with the final report expected to be released by the end of 2020. The preliminary report shows all four sites have indicators of improvements, notably the Strathbogie and Mt Wickham sites.

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Reef regulations - grazing, standard conditions

  1. For land in good or fair condition (more than 50 per cent ground cover at 30 September), continue using measures to maintain land condition.
  2. For land in poor condition (less than 50 per cent ground cover at 30 September), steps must be taken to improve land condition.
  3. For land in degraded condition (less than 20 per cent ground cover at 30 September), steps must be taken to improve land condition OR prevent areas from further degrading or expanding.
  4. Keep records of measures taken and also of agricultural chemicals, fertiliser and mill mud or mill ash applied to land.