In a recent submission on floodplain harvesting, the EDO and the Wentworth Group of Concerned Scientists argued that “conferring permanent property rights to irrigators is a windfall transfer of public wealth that should be considered only once public good outcomes can be guaranteed, including for Aboriginal Nations who are disproportionately disadvantaged under the current policy settings.”

In our latest water law article, we explore this controversial practice in more detail and set out a list of recommendations to protect the environment, downstream communities and Aboriginal rights and interests.

By Dr Emma Carmody, Managing Lawyer, Freshwater Team
Nadja Zimmermann, Solicitor, Freshwater Team

What is floodplain harvesting and where does it happen?

Floodplain harvesting occurs during wet periods when large volumes of water breakout over the river bank and spread out across vast floodplains. As water moves across these flat expanses, long, low engineered structures such as access roads, channels and levee banks can intercept and divert considerable volumes of water that would have otherwise remained as wetland habitat, flowed downstream or soaked into aquifers. This water is then generally stored in on-farm dams or off-river storages which can be considerable in size (for example several kilometers by several kilometers long).

Floodplain harvesting is very common in the northern Murray-Darling Basin (MDB) due to the variable nature of river flows and the significant number of floodplains and wetlands in these parts of northern NSW and southern Queensland. However, it also occurs in the southern MDB, for example in the Murrumbidgee catchment.

Floodplain harvesting is currently an unlicensed activity. However, the NSW Government has for some time been working to implement its Floodplain Harvesting Policy (FPH Policy) which would involve licensing floodplain harvesting on ‘designated floodplains’ in five northern catchments.[1] These licences will be issued under the Water Management Act 2000 (NSW) (WM Act).

What are people concerned about?


There are benefits to bringing floodplain harvesting within a licensing and associated compliance framework, such as a requirement that the water taken under a licence must for the first time be metered and measured.

Further, not all floodplain harvesting that has occurred up to the present day will be licensed (that is, the licensing is supposed to reduce the volume of water that is being diverted from floodplains).

However, estimates regarding how much water is taken from floodplains vary considerably, depending on the source of the data. Similarly, there is some concern that the hydrological models used to estimate overall water extractions in a catchment and to determine compliance with catchment-wide extraction limits are error-prone, especially in the northern MDB.

A recent report issued by the Wentworth Group of Concerned Scientists found significant discrepancies between how much water one would expect to find in the river, and how much is actually there based on hydrological modelling and expected flows under the Basin Plan. They concluded that this could be due to (amongst other things) modelling errors. These errors can result in discrepancies between modelled and actual water availability and extractions.

This lack of robust data may result in too much water being licensed in a catchment relative to actual water availability for all users and the environment (noting that water availability is decreasing in many parts of the MDB due to climate change).

If over-licensing remains undetected and/or unaddressed, it will invariably affect water access by other licence holders and/or the environment. For example, it could result in annual allocations for other entitlement holders being diminished to accommodate floodplain harvesting.

Alternatively, it could result in the water set aside for the environment in water sharing plans (known as ‘planned environmental water’) being eroded in an effort to maintain allocations for consumptive users. While a reduction in the volume of planned environmental water is illegal under the Basin Plan and Water Act 2007 (Cth) (Water Act), it would have to be detected and proven, which is not a simple task. This is particularly true as the availability of planned environmental water is assessed by the government with hydrological models that are not publicly available. 

Floodplain structures

It is generally acknowledged that some floodplain structures have been constructed without the necessary approvals. However, there is no publicly available information regarding the number of structures that are currently unlawful (or conversely, lawful) or where they are located.

It is also unclear how many unlawful structures will be rendered lawful under the FPH Policy (that is, linked to a licence for water take and issued with an appropriate approval).

Finally, the government has provided some landholders with subsidies to increase the size of their storages located on floodplains. Many people question why taxpayer money is being used in this manner and how it could be consistent with the overall objectives of the Basin Plan, Water Act and WM Act.

Ambiguity regarding structures that are covered by the FPH Policy

The definition of floodplain harvesting contained in the FPH Policy arguably covers a very broad range of structures and storages that result in the collection, extraction or impoundment of water from floodplains. However, it is unclear how the NSW Government is interpreting this definition and whether all structures (such as spreader banks) are covered (and whether associated water will have to be licensed).

Additionally, structures that impound water on floodplains that are not part of ‘designated floodplains’ are not covered by the FPH Policy, which means that these diversions will not be licensed. It is unclear how many such structures and storages exist on non-designated floodplains, how much water they may be capable of diverting and storing, and their impacts on the environment and cultural heritage.

Environmental impacts

Diverting large volumes of water from floodplains over time can have significant, cumulative impacts on the environment including downstream river ecosystems and ecosystem services. This includes on wetlands that depend on these overland flows to maintain their ecological character and on the species that depend on these wetlands for habitat. It also reduces flows into rivers, which in turn affects the volumes of water available for downstream ecosystems and other town and farm communities.

It is questionable whether these impacts are consistent with the Water Act and Australia’s international legal obligations under the treaties that underpin the Water Act, including the Ramsar Convention on Wetlands, the Convention on Biological Diversity and migratory bird treaties. Such impacts are also inconsistent with core aspects of the WM Act, including ‘priority of use’ provisions. In fact, in the absence of downstream flow targets to ensure these legal obligations are met, the licensing of floodplain harvesting could give rise to legal action.

Aboriginal and cultural heritage impacts

We are advised that the majority of Aboriginal people in the northern MDB do not support floodplain harvesting. This is because the floodplain as a whole is of great cultural significance to Aboriginal people, and floodplain harvesting has a detrimental impact on the various elements that make up that whole, including by disconnecting plains from rivers.

Local Aboriginal knowledge and expertise indicates that medium and large floodwater events are decreasing in volume. As a consequence, these replenishing flows are not reaching the top of the banks – let alone making it overbank to refresh elements of the floodplain including wetlands, springs, billabongs, aquifer recharge zones, warrambools (overflow channels that appear during floods), gali (waterholes) and gilgais (small, ephemeral lakes) –  as well as the ecosystems that depend on them.

It is also worth noting that recent research by Lana Hartwig et al revealed that Aboriginal peoples in the NSW part of the MDB own a mere 0.2 percent of available surface water, despite comprising almost 10 percent of the population. Furthermore, Aboriginal ownership of water in this part of the Basin has decreased by 17 percent over the last 10 years.

Against this backdrop, our Aboriginal clients are asking why so little is being done to reverse these appalling statistics but such great effort is being put into creating and distributing valuable water rights for floodplain harvesting. This is particularly true given these new rights offer no tangible benefit to Aboriginal peoples and their communities. Further and as described above, they will result in continued impacts on sites of cultural significance – as well as on food security, water security and on the overall wellbeing of Aboriginal peoples living in affected areas.

Compliance with the Water Act

A baseline diversion limit (BDL) is an estimation of how much water was being diverted across individual catchments in the MDB before the Basin Plan existed (as at 2009). A sustainable diversion limit (SDL) is the maximum volume of water that can be extracted in each catchment and across the entirety of the MDB under the Basin Plan.

The modelling underpinning the Basin Plan (which sits under the Water Act) significantly underestimated the volumes that were being diverted from floodplains in northern NSW and southern Queensland. The MDBA proposes to increase BDLs in affected catchments to account for new information about how much water was being diverted via floodplain harvesting in 2009. This is not in-and-of-itself problematic. However, they are also proposing to increase SDLs by the corresponding volume (that is, increase extraction limits).

It is our legal opinion that increasing SDLs in this manner will result in SDLs (including the Basin-wide SDL) breaching s.23(1) of the Water Act. This section states that an SDL must always reflect an ‘environmentally sustainable level of take’ (ESLT). This is arguably one of the most important, unequivocally binding provisions in the Act.

What to do?

The EDO acknowledges that floodplain harvesting involves a very complex set of legal, environmental, social and cultural issues. However, we believe that the following actions are important if floodplain harvesting is to be undertaken consistently with broader legal requirements under state and national water laws and is to gain broader acceptance amongst concerned individuals and groups.

Measurement, monitoring, transparency

  1. The NSW Water Register should include a publicly-available, spatially-explicit database of floodplain harvesting structures, their ownership, licence conditions and approvals. This should be complemented by information regarding storage volumes and contributions to diversions each year.
  1. The existing basin-wide water accounting framework should be updated and refined to include floodplain harvesting, and the effects of climate change on river flows.
  1. A basin-wide model and regular hydrological auditing should be developed and implemented to ensure knowledge and data regarding the water balance is being continuously refined and improved.


  1. Floodplain harvesting licences should not be tradable as they are linked to specific structures in specific places.
  1. Licence conditions and water sharing plan rules should include ‘downstream flow targets’ which stipulate the volumes of water that must be recorded at downstream river gauges before floodplain harvesting can occur (to meet stock and domestic water supply and ecosystem needs, respectively). This would ensure that these needs are met – or will be met within a given timeframe[2] – before floodplain harvesting can take place.[3]
  1. All licenses must include conditions which provide for Individual Daily Extraction Limits (IDELs) and Total Daily Extraction Limits (TDELs) to protect held environmental water and planned environmental water during overbank flow periods.

Floodplain structures

  1. All legal floodplain structures should be capable of being ‘switched off’ to allow for the passage of water during periods when diversions are temporarily prohibited or restricted so as to meet stock and domestic, environmental and cultural needs. This can be achieved by modifying structures with culverts or regulators. No structures should be attached to a FPH water licence unless they meet this condition.

Aboriginal peoples and their communities

  1. The United Nations Declaration on the Rights of Indigenous Peoples must be upheld in relation to floodplain harvesting. This requires the principle of free, prior and informed consent to be applied to decisions concerning the regulation of overland flows and subsequent impacts on Aboriginal cultural heritage.
  1. Aboriginal landholders must be granted floodplain harvesting licences to use for cultural and/or economic purposes, as they see fit.
  1. Consideration must be given to the reallocation of water to Aboriginal peoples and their communities with the method to be determined by Aboriginal peoples. For example, a percentage of the floodplain licences that would otherwise be issued to irrigators could be reallocated to Aboriginal peoples and their communities.
  1. Licence conditions and water sharing plan rules should include ‘cultural flow targets’ to ensure that – at a minimum – sites of cultural significance receive water before floodplain harvesting can occur. This would ensure that these needs are met – or will be met within a given timeframe[4] – before floodplain harvesting can take place.[5]  

Compliance and enforcement

  1. Penalties for non-compliance with water laws, including conditions and rules governing diversions from floodplains, must be increased if they are to act as a deterrent.
  1. The following Information regarding unlawful structures should be made publicly available:

    a) the current number and nature of unlawful structures and the catchments in which they are located;
    b) how many of these are likely to be rendered lawful under the FPH Policy and associated regulatory changes; and
    c) when those that will not be rendered lawful under the FPH Policy will be removed from floodplains in affected catchment.
  1. Any amendments to the Basin Plan and water resource plans to accommodate floodplain harvesting must not breach s.23(1) of the Water Act.

The Environmental Defenders Office is grateful for the input and feedback that we received in relation to this article by a range of clients and experts including Aboriginal water experts, climate modelers, geographers, freshwater ecologists and other scientists.


Commonwealth Environmental Water Holder, Submission on NSW approach to floodplain harvesting (2018).

Department of Industry, Floodplain Harvesting Policy (2013, updated 2018).

Lana Hartwig, Sue Jackson and Natalie Osborne, ‘Trends in Aboriginal water ownership in New South Wales, Australia: The continuities between colonial and neoliberal forms of dispossession’ (2020) 99 Land Use Policy 104869.  

Loch, A., Pérez-Blanco, C.D., Carmody, E. et al. Grand theft water and the calculus of compliance. Nat Sustain (2020).

Steinfeld C; Kingsford R, Disconnecting the floodplain: Earthworks and their ecological effect on a dryland floodplain in the Murray-Darling Basin, Australia (2011) Regulated Rivers Research and Management, vol. 29.

Wentworth Group of Concerned Scientists, Assessment of river flows in the Murray-Darling Basin: Observed versus expected flows under the Basin Plan 2012-2019 (2020).

S.A Wheeler, E. Carmody, R.Q. Grafton, R.T. Kingsford, A. Zuo, The rebound effect on water extraction from subsidising irrigation infrastructure in Australia (2020) 159 Resources, Conservation and Recycling.

[1] ‘Designated floodplains’ are specific parts of the floodplain that are designated under NSW water laws.
[2] This is to take into account the time it can take for water to flow downstream (which can be weeks after a significant rain event).
[3] These would include restrictions on ‘carryover’; appropriate water accounting rules; and restrictions on the timing of extractions.
[4] This is to take into account the time it can take for water to flow downstream (which can be weeks after a significant rain event).
[5] These would include restrictions on ‘carryover’; appropriate water accounting rules; and restrictions on the timing of extractions.