Changes in water use, quality and supply

One of the trend and condition reports (aquatic ecosystem condition) is based on assessments undertaken by the EPA. Since 2008, the EPA has carried out 544 assessments of aquatic ecosystem condition across all of SA’s regions, using a 6-tiered condition rating system, ranging from ‘excellent’ to ‘very poor’ (Figure 37).

The assessment uses a range of science-based approaches and models that capture the biological, chemical and physical changes occurring in streams and lakes in relation to increasing levels of disturbance.

The EPA has not rated any site as ‘excellent’ since the monitoring program began in 2008. It has rated 17 as ‘very good’, 95 as ‘good’, 209 as ‘fair’, 191 as ‘poor’ and 32 as ‘very poor’ (Figure 38).  

With the degree of human disturbance across SA, and the typically low flow volumes in most creeks and streams, it is not surprising a greater proportion of sites are in ‘poor’ rather than ‘good’ condition.

The distribution of assessments across various regions of SA is particularly interesting, as seen in Figure 39.

In general, the differences between regions are due to rainfall levels and degree of native vegetation clearance. The better sites being located in high rainfall areas with catchments still having a high percentage of native vegetation.  

The Adelaide and Mount Lofty Ranges region has been extensively cleared since European settlement, with only about 15% of the original vegetation remaining (Figure 40). The remnant native vegetation exists in relatively undisturbed locations, such as conservation parks, steep hills, gullies, along creek lines and as part of roadside vegetation. Agriculture dominates the region (mostly stock grazing and cereal cropping), and there are extensive urban areas, including the city of Adelaide.

Kangaroo Island is a case in point where there is a clear trend of ‘good’ to ‘poor’ assessment results moving from west to east. The streams in good health are on the high rainfall and more vegetated western end of the island. Land use is dominated by nature conservation throughout the western end. Cropping, stock grazing and forestry dominate the middle and eastern parts of the island. Eastern parts typically only retain patches of remnant native vegetation along hilltops, creek lines, roadsides and around salt lakes and swamps.

The higher proportion of healthy streams in the Northern and Yorke and SA Arid Lands regions demonstrates the relationship between rainfall, vegetation and aquatic ecosystem condition. The Northern and Yorke region includes some of the Flinders Ranges, where agriculture has had less of an effect on streams than the rest of the region due to the presence of more natural areas.

Similarly, the better streams in the SA Arid Lands region are in areas with largely intact remnant native vegetation throughout their catchments, and generally show little to no damage caused by stock or feral animals. These include Oraparinna in the south within the Flinders Ranges National Park to Arkaroola in the north within the Vulkathunha-Gammon Ranges, and Yardaparinna Creek in the Western Lake Eyre Basin.

No streams on the Eyre Peninsula are in the ‘very good’ or ‘good’ condition categories, and a high proportion (62%) are rated ‘poor’ to ‘very poor’. The ephemeral nature of these streams limits their ability to flush salts and nutrients, resulting in them being highly saline and nutrient enriched.

Most streams were probably naturally saline prior to European settlement, but have been further salinised by extensive native vegetation clearance occurring from the 1880s to around the mid-1970s.

The South East region has been substantially modified by artificially constructed drains with few naturally occurring creeks. The drains and wetlands provide, in some locations, significant habitat for surviving aquatic biota. Sites receiving point-source discharges, urban stormwater or located within heavily cleared catchments rated as having the poorest condition in the region. Agricultural land uses contribute large loads of nutrients, salt and fine sediment to most drains and streams in the region.

In the SA Murray–Darling Basin region, agriculture (grazing and dryland cropping) dominates land use. There are also areas of irrigated vines and orchards, dairying, forests, urban areas, mines and remnant native vegetation. Only about 15% of the original vegetation remains.  

The Eastern Mount Lofty Ranges has been particularly targeted for cropping and grazing, and only about 8% of the original pre-European vegetation, for example  grassland and grassy woodlands remains.

Five water-related targets were included in the now expired South Australia’s Strategic Plan. These related to increasing stormwater harvesting, increasing wastewater recycling, sustainable water resource management, and River Murray flows and salinity.

For the 2016–17 assessment of progress against the target of capacity (does not reflect the actual amount reused) to harvest 35 GL of stormwater by 2025, SA was at almost 23 GL per year, up from less than 6 GL per year in 2008–09. Subsequent projects are underway to further increase total capacity.

Stormwater harvesting projects usually require water being treated before storage and the risk of contamination and need careful management. A number of risks from contaminated stormwater have been identified in a recent study of Mount Gambier, where urban stormwater is discharged to groundwater and ultimately may reach the Blue Lake. 

South Australia exceeded its target 15 years early to reach a capacity to recycle 50 GL of wastewater per year by 2025. The recycling capacity has been stable at just more than 70 GL per year since 2010. In 2016, 32.2 GL of the available recycled wastewater was used. Taking up the full capacity would require expanding distribution networks and increasing uses of recycled water. One significant new use is the Northern Adelaide Irrigation Scheme, which will take 20 GL per year of recycled water from the Bolivar Wastewater Treatment Plant.

This target measured the extent to which SA’s water resources are managed within sustainable limits. There are 67 water management areas, predominantly defined by natural catchments and groundwater resources areas. Of these, 36 areas have been assessed as being managed within sustainable limits and 29 as partially within sustainable limits. This number has remained stable from 2003 to 2016.

Mechanisms for water management are provided through water allocation plans for prescribed water resources and regional natural resources management plans. Water planning and management across South Australia is guided by a 5-year plan that enables coordination of efforts and resources, and clarification of priorities.

It is unlikely SA will achieve its goal to manage all water resources within sustainable limits by 2018. This goal is more likely to be met if wastewater recycling and stormwater harvesting capacity are included.   

The target to increase environmental flows in the River Murray to ensure adequate water for a healthy river system has been achieved and exceeded through recovery of water for the environment under the Living Murray Program, the Murray–Darling Basin Plan, as well as water held by the SA Government for environmental use (including as part of the funding agreement for the Adelaide Desalination Plant). The Basin Plan environmental water management framework now provides the primary means for coordinating environmental water use across the Murray-Darling Basin.

Read more about the progress of water recovery under the Basin Plan at Murray‒Darling Basin Authority

Meeting the Basin Plan targets by itself does not guarantee adequate environmental flows to ensure a healthy River Murray, and some habitat loss will continue.

River Murray salinity

The target to maintain a positive credit balance on the Murray‒Darling Basin Authority salinity register is being met, with SA maintaining a positive credit balance of $7.035 million per year on the Salinity Register as at November 2016. U

nder the Murray‒Darling Basin Agreement, SA is responsible for actions that change salinity in the River Murray. For example, increased irrigation results in a debit on the salinity register, whereas salt interception, improved irrigation efficiency and rehabilitation of drainage schemes result in credits.

EPA reported incidents

The EPA maintains a pollution reporting and enquiries hotline. As shown in Figure 41, there has been an upward trend in the number of calls related to the pollution of water during 2013‒14 to 2016‒17. This may be a result of the increased awareness created through the EPA’s community engagement and the development of the Environment Protection (Water Quality) Policy 2015.

Following the introduction of the Local Nuisance and Litter Control Act 2016, local councils are starting to deal with more of these incidents and enquiries.

Emergency response incidents are included in these figures. The EPA provides a 24-hour on-call Emergency Response Team (ERT) responding to requests for expert advice and incident attendance in relation to emergency pollution and hazardous substances. Of the 433 incidents reported to the ERT during 2015‒16, a total of 121 were related to water pollution. Most of these came from the public, which indicates a good awareness of the importance of our water resources.