Environmental water
What is it and how is it delivered?
There are two types of environmental water – Held Environmental Water (water entitlements that have been acquired to deliver environmental benefits and are held and managed by Commonwealth and State Environmental Water Holders) and planned environmental water (water that has been committed to supporting the environment through legal rules in state government water management plans and is protected from other uses). We will focus here on the delivery of Held Environmental Water managed by the Commonwealth Environmental Water Holder, referred to here as Commonwealth Environmental Water.
What is Commonwealth Environmental Water?
Commonwealth Environmental Water is water entitlements that are managed by the Commonwealth Environmental Water Holder for the purposes of achieving environmental outcomes. This water has been acquired by the Federal Government (such as through purchasing water or from water savings from investing in more efficient water infrastructure) to return to the environment. Each year, the water is available to be delivered to the environment with the aim of achieving the best possible environmental outcomes.
How much Commonwealth Environmental Water is available?
As of 31 May 2026, the Commonwealth Water Holdings (for surface water) were 3121 GL of water entitlements. These water entitlements have differing levels of security, meaning they will yield different volumes of water depending on water availability. Each year, state governments allocate water to entitlement holders according to their methodologies, which differ between states, based on water availability and other factors.
The Long Term Diversion Limit Equivalent (LTDLE) factor was developed as a method of comparing the water recovery equivalence of different classes of water entitlements. LTDLE (rather than the total volume of entitlements) is the figure that is used to assess progress towards the Basin Plan water recovery target of 3200 GL/yr. The LTDLE of the 3121 GL of Commonwealth Environmental Water is 2164 GL.
However, as we can see in the graph below, the volume of water that is allocated each year by state governments is well below the LTDLE. On average from 2008 to 2025, the annual allocation of Commonwealth Environmental Water was 75% of the LTDLE. This leaves a significant gap between what is considered to have been recovered for the environment, and what is actually available each year to be delivered to rivers and wetlands.
How much of the surface water available to the Commonwealth Environmental Water Holder is delivered each year?
From 2008 to 2026, 93.3% of the surface water allocated to the Commonwealth Environmental Water Holder has been delivered.
Over that period, 3.2% of total allocated water was carried over to 2026-27, 2.3% was lost to dam spills and other adjustments, 0.9% was lost to evaporation (as prescribed by water accounting rules), 0.3% was traded and 0.2% was forfeited.
What is carryover of water and how does it work?
Carryover is when water allocated in a given year is not used in that year, instead is carried over to be used the following year. This is an important tool that provides flexibility to help to make the best use of water for environmental outcomes. For example, it allows the Commonwealth Environmental Water Holder to either deliver water at a seasonally appropriate time (i.e. winter) when new season allocations are typically low, or to manage the delivery of allocations over one or more years in catchments where new allocations are insufficient to meet environmental demands.
Could Commonwealth Environmental Water be used more effectively?
Yes, it could. However, there is a lot of work required by Commonwealth and State governments to remove the significant barriers that prevent the delivery of environmental water to some areas of the Basin. For water to reach floodplains and wetlands, flows need to spill over river banks, which requires what are known as overbank flows, or controlled flooding. There remain barriers to delivering these flows due to issues such as roads and bridges that would be inundated, and inundation of low lying private land. In some areas these barriers are preventing water managers from delivering water to wetlands that badly need it. Addressing these barriers, known as constraints relaxation, needs to be progressed as a high priority so that water can reach wetlands and floodplains. You can read more on our Bringing Wetlands Back to Life page.
Who is the Commonwealth Environmental Water Holder?
The Commonwealth Environmental Water Holder is a position established under the Water Act 2007 to manage Commonwealth Environmental Water Holdings. Since October 2022, Dr Simon Banks has held this role. The Commonwealth Environmental Water Holder is subject to the same fees, allocations, carryover and rules as other water users.
More information and data can be found on the website of the Commonwealth Environmental Water Holder https://www.dcceew.gov.au/cewh
