Water resources

Water is essential for the liveability of the ACT and the surrounding catchment areas. Rivers and streams provide water for our homes and gardens. They also support the environment, recreation and cultural activities.

Most of the water consumed in the ACT is for use in urban areas. Unlike many other areas of the Murray-Darling Basin, very little water is used for agriculture.

The Office of Water manages water policies and programs for the ACT Government. The Office works with the Australian Government, other states and territories, Icon Water, and nearby councils in New South Wales. Its goal is to improve how we manage water, maintain its quality, and keep it secure.

Where water in the ACT comes from

Murray-Darling Basin

The ACT sits within the upper Murrumbidgee River Catchment in the Murray-Darling Basin. The Murrumbidgee River, Molonglo River and Cotter River are key waterways in the upper catchment. The Murrumbidgee and Molonglo rivers begin in NSW before coming together and flowing through the ACT. The Cotter River starts in the ACT and flows into the Murrumbidgee River.

The ACT is the biggest city in the Murray-Darling Basin. It plays an important role in looking after the valuable and limited water resources in the area.

Surface water

Surface water is any water on land or flowing over land after:

• falling as rain, snow, sleet, or hail
• rising to the surface naturally from underground
• being returned to the environment after treatment or use.

All surface water passing through the ACT goes into the Murrumbidgee River.

In the ACT, there are many natural freshwater wetlands. These wetlands are usually found close to big rivers and creeks.

The Assessment of the ACT Surface Water Resource Under Historical Climate Scenario technical report [PDF 3.6 MB] provides information on the long-term average surface water resources in the ACT.

Groundwater

Groundwater is water located below the Earth's surface. It filters down and is stored in layers of rock, gravel, or sand.

In the ACT, groundwater resources are small and not very deep compared to other parts of Australia. In the ACT, there are two types of geological formations that hold groundwater, called aquifers:

1. Aquifers in fractured rock
2. Aquifers in soils and sediments around rivers (alluvium aquifers)

Both types of aquifers can be fairly shallow and support special ecosystems that depend on groundwater. In the ACT, the only known groundwater‑dependent ecosystems are small streams that are not regulated and mostly get their water from nearby groundwater. Groundwater from both aquifer types eventually flows into these streams. Environmental flow guidelines set limits on how much groundwater can be safely taken.

Potable water

Potable water is water that is safe for drinking or using in food preparation.

Icon Water owns, manages and operates potable water services for the ACT. This includes a network of dams, water treatment plants, reservoirs, pumping stations, mains and other related infrastructure. Potable water in Canberra is sourced from surface water sources. After treatment it is stored in water supply reservoirs, before being piped to customers.

Non-potable water

Non-potable water is not suitable for humans to drink or prepare food with, but it can be used for other things.

Licensed non-potable water in the ACT is sourced from rivers, lakes, groundwater, recycled water, and rainwater. This water can be used to water parks, sports fields, golf courses, and crops. It can also provide drinking water for animals and meet various industrial needs.

Wastewater

Wastewater is water that drains to the sewer. It comes from activities like showers, flushing toilets, washing dishes, and industrial activities. It can contain substances that might pollute our rivers or harm our health if it is not treated.

The Lower Molonglo Water Quality Control Centre is the ACT’s main wastewater treatment plant. It is also the largest inland treatment facility in Australia. Some recycled water is used for running the plant and for irrigation. Most of the treated wastewater goes back into the Molonglo River, where it meets the Murrumbidgee River.

Stormwater

Stormwater is water that runs off surfaces like roads, roofs, driveways, and sidewalks instead of soaking into the ground. As it moves, stormwater can collect harmful dirt and chemicals and carry them into our rivers and lakes.

To help with the impact of stormwater, the ACT has Lake Burley Griffin, Lake Tuggeranong, Lake Ginninderra, and 198 built wetlands and ponds. The ACT Healthy Waterways Program also helps homes, businesses, and schools find ways to cut down on harmful pollutants right where they start.

Environmental Water in the ACT

Environmental Water is water that is set aside to keep rivers, wetlands and the plants and animals that live there healthy. It helps support ecosystems by giving them the water they need to survive and stay in good condition.

Environmental Water plays a key role in supporting the health of rivers in the ACT. Environmental Water released from ACT reservoirs help to:

• keep rivers connected along their full length
• support native fish movement and lifecycle needs
• protect in-stream and riparian habitats
• maintain water quality in the ACT and downstream.

Environmental Water helps keep our waterways healthy during dry times. It supports native fish and other aquatic life. It also helps maintain places the community values for recreation, culture, and the landscape.

Held Environmental Water

Held Environmental Water is water that is set aside and actively managed specifically to achieve environmental outcomes. The ACT does not hold or manage Held Environmental Water. In the ACT, Planned Environmental Water (PEW) delivers environmental outcomes.

The Commonwealth Environmental Water Holder (CEWH)

CEWH manages Held Environmental Water across the Murray-Darling Basin. This includes in the Murrumbidgee River downstream of the ACT.

The CEWH currently holds 6.36 gigalitres of Environmental Water in the ACT. The ACT granted this entitlement to fulfil the ACT’s water recovery obligations under the Murray-Darling Basin Plan 2012.

Learn more about the role of the CEWH and environmental watering on the CEWH website.

Planned Environmental Water

Planned Environmental Water is water reserved for the environment through rules in water plans, licences and guidelines. Operating plans for dams, reservoirs and rivers all contain details about PEW.

In the ACT, PEW is delivered through the ACT Environmental Flow Guidelines. The guidelines were established under the Water Resources Act 2007. They set:

• flow requirements that specify how much water should be released from dams, and when
• abstraction limits* to help maintain river health.

*Abstraction limits are rules that set the maximum amount of water that can be taken from a river, lake or groundwater source.

PEW helps to:

• keep water clean by stopping it from becoming still and low in oxygen
• keep native fish, small water animals and riverside plants healthy by creating more natural water flows
• protect river habitats by keeping the channel in decent shape and maintaining diverse types of flows
• support community values, including cultural connections, recreation and the natural beauty of rivers
• assist rivers to cope better with drought and climate change.

How the Environmental Flow Guidelines operate

Under the ACT’s Environmental Flow Guidelines:

• planned releases are made from dams such as Cotter Dam and Googong Dam

• releases are designed to meet minimum flow targets and seasonal patterns
• environmental flows are balanced with water supply needs, including during drought
• flow releases and abstraction limits are adjusted in response to:
  • seasonal requirements (for example fish passage)
  • inflow conditions and/or
  • storage levels.

Environmental releases and abstraction limitations are planned and predictable. This provides a consistent level of support for river ecosystems over time.

Water trade

Water trade is the regulated buying, selling, or transferring of water rights. Water rights can be traded freely, except where they are restricted by physical constraints or trading rules.

Water trading is a key feature of the Murray-Darling Basin Plan (Basin Plan). It allows water to move to where it is needed most, supporting the environment, agriculture, towns and communities. The Basin Plan water trade rules guide how water is traded in the Murray–Darling Basin. They set clear standards to:

• make the market more open
• reduce limits on trading
• keep the rules consistent across state borders.

The Water Resources Act controls how water access entitlements can be traded in the ACT. The ACT Environment Protection Authority regulates these trades and reports on them.

The ACT and NSW governments are working together to create the first shared water trading framework for the region. This new framework will let Environmental Water from the ACT flow into the Murrumbidgee River in NSW. Here it can help support the river, local ecosystems and nearby communities.

The ACT Government is also working with the Australian Government on major Murray–Darling Basin water market reforms. These reforms aim to make the system more transparent and improve data reporting. The main changes will start in July 2027.

Community perspectives on waterways

Members of the ACT and Region Catchment Management Coordination Group supported several community surveys. These help inform water resource management in the ACT and region.

• Community Voice towards Waterways – ACT Report 2025
• Community Voice towards Waterways – ACT and Region (Queanbeyan-Pelarang, Snowy Monaro, and Yass Valley) Synthesis Report 2025
• Connections to the Upper Murrumbidgee – ACT and region community survey 2024
• Water quality and the community - ACT and region community survey 2016

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