Water quality

2016

Water quality in SoE 2011 was assessed as a significant one-off activity, involving collection, collation, analysis and assessment of water quality data from thousands of sites across Australia. A comprehensive report considered water quality at the river-region scale, and information was aggregated to the drainage-division scale. Such an analysis was not done for the 2016 update, and assessment is based on consideration and collation of a range of sources at state, region or river scale.

Available data

Assessment of water quality, including groundwater quality, is more complicated than assessing groundwater levels and trends, and much more complicated than assessing surface-water flows and levels. A wide variety of water quality parameters are collected using a range of methods, for sometimes disparate purposes. Available water quality data and metadata were evaluated in the context of supporting Australian Water Resources Assessments. It was found that the potential existed for more than 1,500,000 combinations of site and water quality parameters across the country, and many hundreds of other parameters, with multiple names for seemingly similar parameters. Thus, development of a national data model and collation of a comprehensive national database, as done for groundwater data, would be many years’ work.

A challenge in assessing water quality is selecting an analysis method. Methods continue to develop as our understanding of the potential uses of water quality data develops. Penev et al. (2014) investigated a statistical method to analyse water quality trends in the Shoalhaven region of New South Wales. A mixed data sampling regression method was used, accounting for some of the mixed frequency of data collection used in water quality sampling, as well as the mixed contributions of rain and flow. The authors concluded that the method could distinguish between these contributions, and that the effects of flow on water quality are likely to be more complicated than the effects of rainfall. These types of methodological developments offer the potential to better inform our management around water quality and aquatic ecosystems.

Spatial representativeness is another challenge faced for this and other assessments that use point-sampling data. For some environmental variables, such as rainfall, a local observation is sometimes quite different from regional or synoptic values. Surface-water quality measured at a point integrates many of the processes occurring in upstream catchments, whereas groundwater salinity or acidity can also be a measure of larger-scale factors. Thus, the approach used here focuses on larger, more comprehensive reports that include water quality, with a few individual cases to provide emphasis or counterpoint.

There is no single national repository of data on surface-water quality, nor are there any regular national or state-scale assessments. As part of its national role in water information, the Bureau of Meteorology is investigating the provision of continuous water quality data alongside flow data on the web. Although this is significantly more complicated than collating, standardising and publishing flow data, it is possible that a first tranche of reporting will be available in 2016–17. The Bureau’s Groundwater Insight tool provides information on groundwater salinity for Australia.

States and territories manage water quality monitoring and associated databases for a variety of business purposes. Associated ‘data portals’ associated with these offer access at the site level, with very limited support for aggregating and summarising data at the basin and drainage-division level. State and territory monitoring often focuses on key common parameters of water quality, such as sediment, salinity, electrical conductivity, phosphorus, nitrogen and dissolved oxygen, although many individual sites have a full spectrum of water quality parameters. Other parameters, such as organic carbon, are also of major relevance to aquatic ecosystems, as is acidity, particularly in areas with acid sulfate soils. One other area of surface-water quality that has gained attention in recent years is that of blackwater events, including investigation of drivers and effects on aquatic fauna (King et al. 2012, Whitworth et al. 2012, McCarthy et al. 2014).

Regional results

The Queensland ambient network of surface-water quality has some 18 sites located in the Carpentaria Coast division. The most recent Queensland SoE report, which provides some assessment of water quality, is from 2011. The bulk of the division has nonsaline groundwater, with areas of saline groundwater along the Rosie and nearby rivers, and inland in the south-western areas of the Nicholson – Leichhardt River region.

The Lake Eyre Basin Rivers Assessment 2013–14 monitoring report was released in 2015 and provides the most recent division-wide assessment. Water quality observations were collected from 44 fish-monitoring sites, and various parameters (temperature, dissolved oxygen, conductivity, pH and turbidity) were also measured at gauging stations in the Cooper, Diamantina, Finke, Georgina, Macumba and Neales catchments. For 47 sites, 226 stream water quality samples of each parameter were reported. Many sites across the basin had zero flow at various periods during 2013–14. Water quality was assessed at each fish-monitoring site and was found to be within the range of tolerance for fish species in the Lake Eyre Basin. For in situ sites, water quality parameters in the Diamantina, Warburton, Cooper and Barcoo catchments were within the range of previous reporting rounds. Overall, water quality was generally consistent for the sample period and hydrological conditions (Mathwin et al. 2015).

Basin-scale water quality assessment for the Murray–Darling Basin division can be gained from multiple sources, including state and territory SoE reports; Basin-wide assessments, such as the Sustainable Rivers Audit and Basin-focused water quality assessments (e.g. Henderson et al. 2013); monitoring and reporting as part of implementation of the Basin Plan; and individual multicatchment or sub-basin reports. The 2013 Victorian SoE report (Victorian Government 2013a) was unable to obtain a water quality assessment for the Victorian Murray–Darling Basin catchments, whereas the 2015 New South Wales report (NSW EPA 2015) marked nitrogen and phosphorus levels as moderate, with both having a decreasing impact and reasonable information availability. The most recent SoE report for Queensland is from 2011. The 2015 Australian Capital Territory SoE report (Commissioner for Sustainability and the Environment 2015) rates most water quality indicators as either good or very good, with total nitrogen the only very poor indicator. Trends in the Australian Capital Territory are mostly for improving water quality. The 2015 water report card for the Murray River in South Australia (DEWNR 2015) identified that, in 2014, 75 per cent of the water quality targets for drinking water, 67 per cent for recreation, 87 per cent for flow management and 100 per cent for irrigation were met. Trends in meeting water quality targets were stable during 2010–14.

The Sustainable Rivers Audit is the most comprehensive Basin-wide river health assessment available; however, the most recent report (MDBA 2012) covers 2008–10, so is not relevant to condition assessment after 2011. The Long-Term Intervention Monitoring Project may support broadscale water quality assessment in the future, although reporting at this early stage is focused largely on the water quality impacts of individual environmental flow events. For salinity, the Basin Salinity Management Strategy (BSMS) 2013–14 annual implementation report states that:

When considered over the climatic conditions during 1975–2000, mitigation works and measures put in place to 2014 have delivered an average daily salinity outcome at Morgan of less than 800 EC (electrical conductivity units) for 98 per cent of the time, compared with an outcome of less than 800 EC for 72 per cent of the time that would have occurred with the works and measures that were in place in 2000. In other words, irrespective of climatic conditions, the incidence of salinity exceedance of 800 EC at Morgan has substantially declined as a consequence of BSMS implementation. (MDBA 2015)

An assessment of trends in physical and chemical aspects of water quality for the Murray–Darling Basin was released in 2013 (Henderson et al. 2013), covering 1978–2012, and including trend assessment for 2003–12. There were broad decreases in nutrients across the period, and increases at some sites for some parameters. The floods of 2010–11 increased most nutrients across most sites—except for nitrogen oxides—and conductivity, turbidity and dissolved organic carbon also increased. Most of these have returned to pre-flood values in the years after the floods, leading to an overall improving water quality trend.

Many of the water quality considerations for the North East Coast division focus on the effects of outflows to the Great Barrier Reef, with Brisbane and the surrounding south-east Queensland region also receiving considerable attention. A recent study of sediment load in Great Barrier Reef catchments investigated errors in load estimation and the predictive power of trends in water quality (Wang et al. 2015). A combination of new regression methods and sampling strategies to increase the predictive power resulted in detection of trends of 20 per cent in the past 20 years, which—although longer than the assessment increment for SoE reporting—offers opportunities to better assess trends and the effectiveness of management across decades.

The 2014 Great Barrier Reef report card estimated nutrient and sediment load reductions of more than 10 per cent from 2009 to 2014, and pesticides decreased by more than 30 per cent (GBRMPA, 2014). These reductions are somewhat on track to meet 2018 targets. Within these, all catchments were reported as having reductions in catchment loads, with Fitzroy representing the highest risk because of load reductions generally below 5 per cent (Queensland Government 2015). Figure WAT15 shows part of the 2014 ecosystem health report card for the Fitzroy Basin, reporting on nutrient conditions in the Theresa catchment. Extensive ecosystem report card information is available online for catchments of south-east Queensland, where catchment water quality ranges from excellent to poor.

Information supporting water quality assessment for the North Western Plateau, Pilbara–Gascoyne and South Western Plateau is scarce. The most recent SoE report for Western Australia was in 2007, and the most recent statewide river water quality assessment was in 2008.

The South Australian Government has increased online reporting of water quality in recent years, including a range of specific site information and an extensive series of NRM report cards, as mentioned above. Data reported from 2012 for sites in the South Australian Gulf, drawn largely from the Northern and Yorke region, included many sites with enriched levels of nutrients and some with sediment arising from erosion. Saline water was also present at some sites. It was also reported that ‘best land management practices are not being widely implemented and despite some improvements in recent years, much remains to be done to reduce the movement of nutrients into streams’ (EPA SA 2012). The 2013 South Australian SoE report indicated that surface and groundwater water quality in the Northern and Yorke region were in variable condition, with variable trends (EPA SA 2013).

Assessments of inland water quality for the South East Coast (New South Wales) division consider streams, groundwater and coastal lakes. The 2015 New South Wales SoE report shows moderate nitrogen and phosphorus levels, with an overall decreasing impact on river health. The 2014–15 annual summary of coastal estuary and river water quality (Dakin 2015) contains temperature and salinity data from 21 monitoring stations, spread from the Richmond catchment in the north to the Shoalhaven catchment, providing information that reflects interactions between coastal rainfall, streamflow and marine influences. At a catchment level, the 2013 Clarence River Estuary report card reported water quality mostly in the poor to very poor categories. The Sydney Catchment Authority (2014) reported that, in 2013–14, nutrients for catchments with significant agricultural or urban development regularly exceeded water quality guidelines, whereas those in unaffected catchments generally did not.

Assessment of water quality for the South East Coast (Victoria) division can be considered across three distinct areas:

  • the east, encompassing Gippsland Lakes and nearby catchments
  • the central area around Port Phillip Bay and Western Port
  • areas west of Geelong.

The Victorian Catchment Management Council (2012) reported groundwater and surface-water condition in Gippsland to be moderate to good, while that for Port Phillip Bay and Western Port was in the poor to moderate range. The western Victorian coastal catchments also had groundwater and surface-water quality in the poor to moderate range. The 2012–13 Yarra River and Port Phillip Bay report card (Victorian Government 2013b) provided a broader range of results, ranging from 23 per cent of sites in poor condition to 13 per cent in very good condition, with a slow general trend towards improved conditions.

For the South West Coast division, water quality in the middle and upper sections of the Swan Canning river system was reported to be moderate to poor. For 2011–15, 53 per cent of monitoring sites met long-term nitrogen targets developed for the Swan Canning system, whereas 80 per cent (increasing to 87 per cent in 2015) of sites met long-term phosphorus targets (Swan River Trust 2015). Reports from the Peel–Harvey streams show high to very high nutrient levels during 2011–13, with no discernible trend. Many local water quality improvement plans are being enacted at present, offering hope for future water quality improvements. The most recent statewide assessment of water quality for Western Australia was completed in 2008.

Most information on water quality in the Tanami–Timor Sea division focuses on Darwin. Darwin Harbour Region report cards (DLRM 2016) provide a snapshot of water quality and the health of aquatic ecosystems across the harbour and its catchment. The 2013 report card indicated that water quality mostly ranged from good to excellent, with grades mostly stable in recent years. Water quality in the Daly River in 2012–13 was similar to that in previous years, with known high nitrogen values in the Katherine and Douglas rivers, and low values elsewhere.

Similar to most other states and territories, comprehensive assessment and reporting of Tasmania’s surface-water quality or river condition have not been completed in recent years, with efforts focused on online data portals, guidelines, targets and plans. In the future, the Tasmanian River Condition Index may fill this gap. A few local assessments are available that give some indication of the state and trend of water quality in Tasmania. The 2015 Tamar Estuary report card noted high pollutant loads in the upper estuary because of high inflows from the North and South Esk rivers, in addition to sewage-plant and power-station contributions. In 2014, Hydro Tasmania reported that water quality was mostly good in the lakes and rivers monitored in that year.

Argent RM (2016). Inland water: Water quality. In: Australia state of the environment 2016, Australian Government Department of the Environment and Energy, Canberra, https://soe.environment.gov.au/theme/inland-water/topic/2016/water-quality, DOI 10.4226/94/58b656cfc28d1