Water quality is fundamental to the ecosystem services that inland waters provide, such as drinking water, cycling of nutrients, maintenance of biodiversity, and recreational and cultural opportunities. Poor water quality has serious implications for the ecological health of inland waters, biodiversity, and human and livestock health.
Water-quality pollution generally arises from point-source discharges (directly from industry and treatment plants) or diffuse sources (runoff from catchments). Regulatory improvements have reduced point-source water pollution. Diffuse sources, such as urban stormwater, are now the most significant contributor to pollution of Melbourne’s rivers, creeks and wetlands. The projected increase in extreme rainfall events in Victoria is highly likely to amplify the effects of urban stormwater pollution unless practical solutions are implemented.
The main water-quality issues for Victoria have traditionally been salinity, turbidity, nitrogen and phosphorus. At a state and national level, these variables are considered the most significant river contaminants. However, there are numerous other variables that contribute to water quality, such as pH, pesticides, heavy metals and temperature, which may have local or regional significance. Water quality is also affected by interactions between these components. For example, salinity and temperature both affect the saturation concentration of dissolved oxygen.
When SoE 2013 was issued, the Department of Environment, Land, Water and Planning (DELWP) had not analysed the raw monitoring data that had been collected, and was unable to provide a statewide assessment of water quality. Consequently, SoE 2013 contained only a limited update of water quality from SoE 2008. The 2008 assessment showed that water quality was generally poor in much of Victoria, particularly in Victoria’s lowlands and in the west of the state.
There has been an increased focus on the water quality sector since 2013. DELWP conducted an internal audit of its water-quality monitoring programs in January 2015, prior to a Victorian Auditor-General’s Office (VAGO) audit into Victorian water-resource monitoring, completed in May 2016.
The VAGO audit made three recommendations in response to a central finding that, although some individual programs are coordinated and governed well, oversight of the individual long-term water-quality monitoring programs in the Port Phillip Bay and Western Port region is deficient. The deficiency was due to inadequate coordination across all programs among the three relevant agencies: DELWP, Melbourne Water and Environment Protection Authority Victoria (EPA Victoria). The issue is less prevalent in the nine other catchments where DELWP has the clear coordination role. Specific findings from the VAGO audit included agencies not having a formal cooperative approach to monitoring, reporting and evaluating the individual monitoring programs in the region, and agencies not sharing and using data efficiently to meet reporting needs. The DELWP and VAGO audits informed the Victorian Government’s water plan, Water for Victoria, released in October 2016.
Other organisations that help to manage water quality are Catchment Management Authorities (CMAs), which develop and implement waterway management strategies, and EPA Victoria, which implements the State Environment Protection Policy (Waters) (SEPP (Waters)) and regulates water quality.
Victoria also contributed to the development of the Basin Salinity Management 2030 strategy, which is responding to the environmental, social and economic risks posed by salinity in the Murray–Darling Basin.
Water-quality monitoring has been a greater focus of state and departmental strategies since SoE 2013. Consequently, SoE 2018 is a significant update to water-quality information, due to the trend data that has been supplied by DELWP on a range of quality indicators measured at approximately 80 sites.
A warmer climate will lead to higher water temperatures, affecting the distribution of many aquatic species. Increased temperatures also have water-quality implications, including reduced concentrations of dissolved oxygen and therefore a potential increase in algal blooms. Increased bushfires will also impact on water quality and riparian vegetation.
Critical challenges facing Victoria’s management of water-quality impacts now and in the future include:
balancing the needs of catchment and waterway health with human and agricultural water consumption needs
managing urban growth and its impact on urban waterway health
ensuring that long-term water-quality monitoring is coordinated and shared among the lead agencies (a key recommendation of the 2016 VAGO audit)
maintaining long-term water-quality monitoring data so that it is easily accessible and suitable for informing policy and strategy development
ensuring a coordinated approach to ‘citizen science’ (which incorporates public participation in research) in the water-quality sector. Citizen science programs are more prevalent in water-quality than in other sectors. Ensuring that lead agencies design and target programs with a similar level of rigour will help to maximise the value of community participation
identifying strategies to tackle the likely increase in stormwater pollution incidents associated with more frequent and intense rainfall events.
Other challenges are mitigating against:
increasing stormwater and wastewater discharges from urban areas
altered water regimes, salinity and algal blooms
an increase in catchment inflows from diffuse sources
localised events, in which individual water-quality stressors, including nutrients, sediments, toxicants and pathogens, exceed objectives.
Note that this section refers to surface water only: groundwater quality is covered in the Water Resources section.