Variability has always been a feature of Victoria’s climate, from drought through to flood events. Large storage dams, water markets and an environmental water reserve are examples of how Victoria manages this variability. Research into this and more is ongoing including that by the Victorian Water and Climate Initiative.

In more recent decades, the water sector has observed changes in the climate that is reshaping the way we manage water. The seriousness of climate change impacts to the water sector became clear during the Millennium Drought (1997 to 2009), which was partly the result of climate change. The 13 consecutive years of drought affected water supplies for households, businesses, agriculture and the environment. A total of 457 towns had water restrictions. The Millennium Drought was a wake-up call for many Victorians and triggered major water policy reforms across the state. The drought was then broken in 2010 with one of the largest flood events ever recorded.

Such conditions and events are anticipated to become more frequent and severe with climate change. Such change brings increased threats to Victoria's water quality. Stream flows in some Victorian catchments are projected to drop by approximately 50% by 2065. Bushfire risk will increase in response to the changes in climate, with the recent 2019/20 'black summer bushfires' unprecedented in scale and intensity. These fires burnt more than 1.5 million hectares across Victoria. Water quality impacts from pest animals, weeds, erosion and land use change remain ongoing issues for the water sector in the aftermath of these bushfires.

In combination with other factors, blue green algae outbreaks are occurring in new water bodies due to warmer temperatures and reduced water flows. Blue green algae has also been recorded during cooler months of the year. Such outbreaks have never been experienced before. For example, between 1978 and 2006, the Murray River had no algal blooms. However, between 2006 and 2016 it experienced four major blooms. One such bloom in early 2016 stretched 1,450km and lasted more than 12 weeks.

The table below summarises the potential impacts of climate change to the water sector.

Changes in climate and extreme events Potential implications for the water sector and communities
Temperature increases

Increased annual demand for water, putting more pressure on water resources

Increased water quality impacts caused by turbidity from drier soils or vegetation dieback, pests, weeds, and increased pathogen growth

Increased recreational value of water bodies to the community which are particularly valued during warmer weather

Increased need to irrigate recreation areas, sporting and parks/gardens

Decreased snow, leading to less inflow to snowmelt-fed water storages in spring

Increased wastewater quality changes and impacts on wastewater infrastructure e.g. corrosion and odour

Increased impacts on other asset performance e.g. mechanical and electrical equipment overheating

Increased drying soils which can cause cracks in underground structures such as pipes

More heatwaves

Increased threats to the health and safety of field crews of limit working hours, potentially impacting on many services to the community

Increased power outages, which may affect water supply and wastewater services

Increased water demand, potentially exceeding the capacity of the water grid

Increased incidence of harmful algal blooms

Lower average rainfall

Decreased stream flow and water quality in natural waterways

Decreased quantity and quality of water available, and possible tensions between water supply for consumptive and environmental uses

More droughts

Decreased quantity and quality of water available for use

Decreased recreational opportunities, both on water (e.g. fishing, swimming) and on land (e.g. poor sports ground surfaces, private gardens)

Increased damage to water, wastewater, drainage and flood management infrastructure due to dry soil which shifts and cracks, or tree roots seeking water sources

More intense rainfall

Decreased quality of water for recreational, cultural, spiritual and environmental uses when wastewater systems spill

Decreased performance of drainage infrastructure, which may require investment to maintain historic service levels

Decreased runoff quality, especially from rainfall events after long dry periods

Increased flash flooding

Increased storm damage to water sector assets

Sea level rise and storm surge

Increased inundation of coastal infrastructure, environmental, cultural, spiritual and recreational sites

Increased saline groundwater infiltration, impacting on wastewater assets, wastewater recycling and availability of water near the coast for agricultural and environmental uses

Decreased effectiveness of low-lying coastal drainage networks, that may be partially filled by sea water

More bushfire weather

Increased impact on water catchments and long-term quantity and quality of water in storages

Increased storages temporarily offline due to contamination from ash or from debris flows, reducing water availability

Increased damage to other water sector assets and recreational, cultural, spiritual and environmental sites

More flash floods

Increased flash floods impacting on urban areas and industry. For larger rural catchments, or places where floods are generally caused by snow melt, the likely future changes in flooding are much harder to quantify

Increased disruption to communities by causing injury, loss of life, property damage, personal hardship and disruptions to regional economies

Increased damage to water sector assets, water-related recreational, cultural, spiritual and environmental assets

Increased disruption of essential water and wastewater services, leading to a spread of waterborne diseases

Page last updated: 12/08/22