6. Factors influencing the Region’s values

Agriculture

Despite global and local disruptions due to the COVID-19 pandemic ¹⁷³⁷ and a short period of decreased growth, the total value of Queensland’s agriculture has rebounded. It is estimated at $24 billion in the 2023–24 financial year, 6.8 per cent greater than the average for the past 5 years.¹⁷³⁸ Many of the important agricultural industries in the Catchment are at historical highs, particularly beef, bananas and cotton, which have all recorded their highest annual production numbers and land use areas since 2010.¹⁷³⁴ 

The total land area under cropping in the Catchment was 1,086,754 hectares (10,867 square kilometres) in 2021, dominated by grain crops and sugar cane (Figure 6.10). This area is less than it has been in the past, mainly driven by cropping declines in the Fitzroy and Burnett Mary natural resource management (NRM) regions from historical highs in the late 1900s. Other NRM regions have steadily increased in area under cropping and are currently at or around their historical maximums.¹⁷³⁴ 

Between 2018 and 2021, agricultural land uses accounted for the greatest areas of vegetation clearing in the Catchment. The motivations for clearing on agricultural land are to maintain or increase productivity, to maintain or increase the market value of the land, or to harvest fodder.¹⁷³⁹ On grazing lands in the Catchment, 440,829 hectares (4408 square kilometres) of vegetation were fully cleared and 39,946 hectares (399 square kilometres) were partially cleared between 2018 and 2021.¹⁷⁴⁰

Vegetation management laws passed by the Queensland Government in 2018 regulate clearing in order to: conserve remnant vegetation and regrowth along waterways in all catchments; minimise land degradation; maintain ecological processes; and prevent the loss of biodiversity.¹⁷⁴¹ By 2020–21, this change had led to a 24 per cent reduction in overall land clearing rates in the Catchment when compared to 2018–19.^2171,2172 The loss of riparian woody vegetation in the Catchment, often linked to agricultural uses, was 47,519 hectares (475 square kilometres). Most of this loss occurred in the Fitzroy, Burnett Mary and Burdekin regions and the bulk of this clearing was lawful.⁹⁵¹

Ground cover levels in the Catchment are strongly influenced by the timing and amount of rainfall across the Catchment, and they have varied substantially since 2019. In 2020, 35 per cent of grazing lands within the Catchment had insufficient late-dry-season ground cover for effective erosion control, driven in large part by low levels in the Burdekin and Fitzroy regions.¹⁷⁴¹ In 2022, this had dropped to 8 per cent.⁹⁵¹

Trends in agricultural land management practices that affect water quality are examined in the land-based runoff section (Section 6.5). 

Mining and resources

Queensland has rich endowments of mineral and energy resources and is a major global producer of high-quality coal. The Catchment includes the Bowen Basin, which is the most important coal-bearing region in Queensland. The resource sector has been a key contributor to the Queensland economy and was worth more than $74 billion in the 2021–22 financial year,¹⁴⁹⁴ accounting for nearly one-fifth of the Queensland economy. The sector continues to be a key source of employment, with nearly 71,000 people directly employed in the sector on average in 2022–23.¹⁷⁴² 

Queensland’s annual exploration expenditure has increased from $436 million in 2015–16 to $771 million in 2022–23, driven by both coal and mineral exploration.¹⁷⁴³ However, the number of exploration permits for coal declined by 40 per cent over the same period, while the number of mineral development licences for coal increased slightly since 2015–16. In 2022–23, around 85 per cent of coal-related exploration permits for coal and mineral development licences with a granted status were located in the Great Barrier Reef Catchment.¹⁷⁴⁴

Statewide, coal production (coking and thermal net output) has declined from an average of approximately 243 million tonnes per annum between 2015–16 and 2019–20, to approximately 220 million tonnes in 2021–22.¹⁷⁴⁴ The number of operating coal mines has remained roughly stable with between 52 and 55 operational mines in the financial years between 2015–16 and 2021–22. Of the 54 operating coal mines in Queensland in 2021–22, 49 were in the Reef Catchment producing 135.4 million tonnes of metallurgical coal and 68.6 million tonnes of thermal coal.¹⁷⁴⁴

In 2023, the proposed Central Queensland Coal Project was refused under the Environmental Protection and Biodiversity Conservation Act 1999 (Cth) (EPBC Act) due to unacceptable risks from increased sediment loads to the Great Barrier Reef World Heritage Area, Great Barrier Reef National Heritage Place and Great Barrier Reef Marine Park.¹⁷⁴⁵ This is the first rejection of a coal mine in the Catchment under national environmental law. Multiple legal challenges to applications and approvals for coal mines in the Catchment, including since 2019, have been based on direct impacts to the Great Barrier Reef and on the broader contribution of coal mines to the drivers of climate change.^1746,1747

Urban and industrial development

Urban and industrial development occupies a small proportion, 1.1 per cent, of the Catchment.¹⁷³⁵ These highly modified environments create downstream impacts, including the generation of sediment and nutrient inputs that enter the Region through point source releases, and diffuse runoff (Section 6.5). While urban and industrial point source releases are regulated, diffuse runoff remains difficult to quantify and regulate.

Overall, the impact on water quality and Reef condition is considered localised and is generally restricted to major urban centres such as Townsville and Cairns. Diffuse urban runoff is also a lower threat than runoff from other major land uses, such as agriculture, due to its relatively small per cent contribution to total load (Section 6.5.1),^40,1748 and given the established regulatory framework for urban and industrial development (Section 6.5). The increasing impact of land-based marine debris, much of which is derived from urban and industrial areas, is an ongoing concern and considered in Section 6.5. 

Artificial light from coastal urban and industrial infrastructure has impacts on the coastal environment that is directly illuminated (nearfield effects). Artificial light pollution from coastal urban areas, industry, ports and marinas also generates an artificial skyglow that is bright enough to elicit biological responses in surrounding marine habitats kilometres from the actual source (Figure 6.11).¹⁷⁴⁹ Biologically meaningful artificial light pollution may cause impacts at depths greater than 1 metre across approximately 13,000 square kilometres of the Reef, depending on the month. During June, July, August and September, these light impacts tend to penetrate deeper waters due to higher water clarity. In February, March and April, these light impacts are usually confined to shallower depths due to lower water clarity.¹⁷⁵⁰ Trends in the extent and depth of light pollution are currently not available. The near-field effects of artificial light from sources such as ports, marinas and ships in anchorages remain a knowledge gap.

Sewage treatment plants

About 60 gigalitres of treated sewage is released in the Catchment’s coastal waters annually, with yearly volumes fluctuating between 66 and 46 gigalitres.¹⁷⁵¹ Nitrogen and phosphorus are present in treated sewage. Improvements at treatment plants have significantly reduced nitrogen and phosphorus concentrations in treated sewage released into the Catchment. Overall, average concentrations of nitrogen and phosphorus have fallen between 2016 and 2019 (Table 6.1). Between 2010 and 2019, the annual total load of nitrogen released from sewage treatment plants fell from around 330 to 223 tonnes. Total phosphorus load fell from 95 tonnes in 2017 to 60 tonnes in 2019.¹⁷⁵¹ 

Based on the monitoring of discharge locations, 50 per cent of council sewage treatment plants are achieving better than 3.3 milligrams per litre total nitrogen and 0.71 milligrams per litre total phosphorus, suggesting a high level of nutrient treatment is being achieved at these facilities.¹⁷⁵² Overall, the modelled contribution of sewage treatment plants to anthropogenic dissolved inorganic nitrogen loads to the Region is minor (1.8 per cent) compared with other sources.¹⁷⁴⁸ The downstream impacts of sewage treatment plants, such as nutrient loads, are subject to water quality targets set out under the Reef protection regulations, and facilities may adopt offset schemes to meet targets. However, a systematic understanding is lacking about the contribution of septic systems to nutrient loads.

Barriers to flow

Barriers across rivers and channels, such as weirs and dams, change the upstream and downstream hydrology and ecology of systems.¹⁷⁵³ Barriers over land, such as bund walls, levees, roads and rail infrastructure, disconnect large areas of habitat.¹⁷⁵⁴ Structures of all sizes that impede water flow have an influence on waterway condition and function. Almost all estuary–wetland systems, in all but the most northern catchments, have been affected by barriers to flow.¹⁷⁵⁴ 

In 2019, 236,751 hectares (2368 square kilometres) of wetland were in a state modified by barriers in the Catchment and adjacent intertidal areas. More than half (142,735 hectares or 1427 square kilometres) of this wetland area has changed from one wetland type to another as a result of these barriers, including 93,571 hectares (936 square kilometres) of lacustrine systems that were originally riverine systems and 42,826 hectares (428 square kilometres) of freshwater wetlands that were originally intertidal wetlands (saltmarsh, saltflats and mangroves) (Figure 6.12).¹⁷⁵⁵

Limiting fish movement across the landscape, through originally connected systems, is a key impact of barriers to flow. Some instream structures, such as high-velocity pipes and culverts that do not present major barriers to hydrological connectivity, can still present a barrier to fish migration. Fish passage barriers have not been systematically recorded across the Catchment, and this remains a knowledge gap. Detailed mapping has occurred across some regions,¹⁷⁵⁶ and for Ramsar Wetlands.¹⁷⁵⁷ Impacts differ substantially among regions. In the Wet Tropics region, most river basins are relatively free from impoundments; however, substantial lengths of the Barron and Tully rivers are impounded.¹²⁸ In the Mackay Whitsunday region, all basins except for the Don River are in a ‘moderate’ or ‘poor’ state in relation to fish barriers. The impoundment condition of the Proserpine River recently declined to ‘poor’.¹⁷⁵⁸ Recent assessments have found more than one potential fish barrier per square kilometre in both the Murray and Lower Herbert rivers and the Mackay Whitsunday basins.^1759,1760

Works are continuing in the Catchment to restore hydrological and ecological connectivity. Works include removing barriers for large-scale restoration of natural hydrology to wetland ecosystems. Examples include causeway removals to restore the Rodd’s Harbour Fish Habitat Area, Rodds Peninsula,¹⁷⁶¹ and bund wall removals at Mungalla Station.¹⁷⁶² These kinds of barrier removal works can provide long-term benefits. For example, the removal of a bund wall in the Mungalla wetlands in 2013 reinstated tidal connection, leading to major reductions in freshwater weeds, the reappearance of native vegetation, improvements in water quality and a tripling of fish diversity over a period of 4 years.⁹³⁸ In the Catchment, coordinated monitoring and evaluation of wetland restoration projects is lacking despite existing frameworks.¹⁷⁶³

Work has also been carried out to enable fish passage. Fish passage works, such as fishways, do not necessarily ensure historical hydrological connectivity, but they usually make barriers more navigable during periods of flow. At least 127 waterway barriers with fishways existed in the Catchment in 2022.¹⁷⁶⁴  An approvals process is in place to control new barriers to fish passage under the Planning Act 2016 (Qld) and Fisheries Act 1994 (Qld). This process results in new waterway barrier works having design elements that promote fish passage through or over the structure. Between 2018 and 2022, 326 development applications and 3332 accepted development requirement notifications were submitted for waterway barrier works in local government areas of the Great Barrier Reef Catchment.¹⁷⁶⁵

While physical works represent substantial improvements at the scale of particular wetland systems, and legislative arrangements reduce the threat of uncontrolled installation of future barriers, legacy barriers remain a widespread impairment to the Reef ecosystem health.¹⁷⁵⁴ 

Tidal works

While quantifiable extent data are available for some works, comprehensive and systematic data on all tidal works and their cumulative impacts are lacking. In 2015, 9 per cent of the Region’s mainland coastline was estimated to have been modified by engineered structures.¹⁷⁶⁶ Most structures occur in marina and port developments, with 60 per cent located within the lower 3 kilometres of estuaries.¹⁷⁶⁶  Contemporary data since 2015 remain a knowledge gap. Beach nourishment and dune restoration are being actively pursued along parts of the coastline, including the Capricorn Coast, Mackay, Burdekin and the Cassowary Coast.¹⁷⁶⁷ Tidal works, such as seawalls, marinas and port infrastructure, create novel marine habitats in the Region, and these urban–industrial seascapes can contain abundant fish communities,¹⁷⁶⁸ though the effects of these structures at the wider population and community level remain difficult to determine.

Linear infrastructure

Privately and publicly owned roads, rail and tracks are types of linear infrastructure. They are not confined to built-up areas and are present across the Catchment.¹⁷⁶⁹ This infrastructure can create a barrier to flow when they cross waterways, and alter flows overland during periods of flooding. New or upgraded roads make marine and coastal areas more accessible and can increase direct use of the Reef. Erosion from linear infrastructure has been identified as a significant sediment source within particular parts of the Catchment¹⁷⁷⁰ and a vector for pests and weeds into remote coastal ecosystems. As of 2021, there were 87,437 kilometres of roads and 41,899 kilometres of tracks in the Catchment.¹⁷⁶⁹ Unsealed roads can be a source of subsurface erosion, which is not currently accounted for in Reef sediment budgets.¹⁷⁷¹ Comparable data on the number and type of barriers to flow created by linear infrastructure across the Catchment are not available. In remote far northern parts of the Catchment, where a large proportion of roads are unsealed, linear infrastructure is potentially the most significant sediment source of any land use impact.¹⁷⁷² In 2021, there was 454 kilometres of linear infrastructure across tidal waterways, mostly local roads and tracks.^1773,1769 The frequent transit of vehicles across intertidal areas causes physical and ecological damage, removing habitat-forming vegetation and altering animal assemblages.^1774,1775

Aquaculture

Aquaculture can affect the marine ecosystem, particularly through the modification of coastal habitats and the water quality of point source releases, leading to, for instance, deoxygenation impacts.¹⁷⁷⁷ Since 2018, Queensland-wide production value has increased dramatically, by approximately 90 per cent, from $118 million in 2018–19 to $225 million in 2021–22. This growth has occurred alongside an increase in the relative importance of aquaculture to Queensland’s total fisheries production.¹³¹⁸ The bulk of this value is derived from land-based aquaculture operations in central and northern Queensland, particularly in Cairns, Townsville and Mackay.¹³¹⁸ The most valuable sectors of the Queensland aquaculture industry continue to be prawn and barramundi.¹³¹⁸ 

In 2021–22, the total ponded area in the Catchment was 990 hectares (9.9 square kilometres). Where increases in production have been made, in most cases they were achieved by intensification rather than expansion of farm footprint.¹³¹⁸ However, 9022 hectares (90 square kilometres) of land-based marine aquaculture development areas have been identified within the Catchment for the aquaculture industry in Queensland.

Since 2019, there has been an expansion of the Proserpine Prawn Farm in the Mackay Whitsunday region. Proposals to roughly triple the production pond footprint are under assessment under the EPBC Act.^1778,1779 Seaweed production is being trialled in farms across the Catchment, including the Proserpine Prawn Farm¹⁷⁸⁰ to reduce nutrients in wastewater discharge. 

No marine-based aquaculture facilities are currently operating in the Region. Recent developments in black lip oyster hatchery production indicate new potential for oyster farming activities to expand into and adjacent to the Region.¹⁷⁸¹ The downstream impacts of aquaculture, such as nutrient loads, are subject to water quality targets set out under the Reef protection regulations, and facilities may adopt offset schemes to meet targets. 

Port development

Port development undertaken directly in the Region is described and assessed in Section 5.7. Land-based aspects of port activities (above the low water mark, including reclamation) form part of the coastal development assessment. Land reclamation occurs when an area is restricted from tidal influence and converted into land above the high water mark.  Systematic reporting of land reclamation above the low water mark, and of historical land reclamation in the Region since European settlement for port and other purposes, remains a knowledge gap.

Point source pollutants from ports are regulated, and impacts on the Region are largely localised, but port activities continue to present a continued risk of point source pollution. Between 2019 and 2022,¹³⁸ pollution incidents were reported within the port limits of Gladstone, Mackay, Townsville and Cairns.^{1782,1783,1784,1785} Coordinated data on the scale and impact of these incidents are not readily available. 

Marine access infrastructure

Marine access infrastructure and launch facilities, such as boat ramps, pontoons and marinas on islands, in rivers and on the mainland coast support local, recreational and tourism access to the Region. Since 2018, 2 new boat ramps have been installed in the Cairns region, 2 in the Mackay region and 3 in the Gladstone region. A new lane was also added to an existing location in the Cairns region, and upgrades were made to existing facilities in all regions ¹⁷⁸⁶ (regions refer to Maritime Safety Queensland Regions). 

Along the Reef coast, the Whitsundays region has been identified as most in need of additional marine access facilities. In late 2023, the Queensland Government announced investment in marine infrastructure at Hook Island, Long Island and Keswick Island.^1787,1788 While some of these facilities are outside the Region, impacts from installation and operation of these facilities may affect the values of the Region. 

Between 2019 and late 2023, a total of 161,475 cubic metres of material was dredged in activities associated with state-owned marine access infrastructure adjacent to or within the Region, including both capital and maintenance dredging.¹⁷⁸⁹ Local governments and port authorities also own public marine access infrastructure in coastal areas adjacent to or within the Region, and they undertake mechanical maintenance activities of these facilities, though coordinated data are not readily available.

Island development 

Most of the land area of the Region’s islands are natural landscapes. The remaining area is mainly occupied by forestry (147 square kilometres on Curtis Island) and grazing land (70 square kilometres, mostly on the islands of Broad Sound). Commercial and urban development (31 square kilometres) on some of the Region’s islands supports tourism resorts, port infrastructure around Townsville and Gladstone, and permanent residential populations.¹⁷³⁵ The principal residential islands include Palm Island (2098 residents) and Magnetic Island (2475 residents), with relatively stable populations over time.¹⁷⁹⁰ The Queensland Government plans to introduce new public facilities in protected areas on islands to enhance ecotourism.¹⁷⁹¹ This includes plans to rejuvenate resorts on Reef islands and build new public access jetties to increase visitors and encourage investment in new and existing island tourism operations.¹⁷⁹² For example, the proposed draft master plan for Woppa (Great Keppel Island) includes a new public plaza, jetty, cultural centre and supporting infrastructure.¹⁷⁹³ Some decommissioned infrastructure, such as the underwater observatories on Green Island and Hook Island, has been actively removed.¹⁷⁹⁴