What is the growth in floodplain harvesting in the northern Basin since 1994?
Using the Border Rivers valley as an example, changes in floodplain development, including on-farm storage volumes, rate of take and irrigated areas from 1994 through to present day, are shown below.
On farm development levels estimates for the four development scenarios (plan limit, Cap, plan limit WSP, eligible development and current conditions).
As a result of growth in development, total long-term average diversions have increased by approximately 6.1 GL/year as shown below. This is an increase of just over 3% for total diversions and around 13% for floodplain harvesting diversions.
Predicted long term (1895 to 2009) average diversions (GL/year) under the plan limit scenario and current conditions scenario to determine growth in use.
Current use above limits will be reduced through the implementation of the NSW Floodplain Harvesting Policy by introducing licencing, entitlements and accounting rules. In the Border Rivers valley, reductions to floodplain harvesting take will be by 13% as per the process below.
Process for using the model scenarios to determine floodplain harvesting entitlements. The four steps, moving from left to right, reflect the relationship between the four model scenarios.
Are the new licence volumes based on the capacity of on-farm dams?
There are approximately 1,400 large on-farm storages in the northern Basin floodplains of the Border Rivers, Gwydir, Namoi, Macquarie and Barwon-Darling valleys. If full, these storages could hold a volume of 1,300 GL. But it is important to note that these storages are not used solely to store water harvested from the floodplain. On-farm dam storages are used for several different purposes, including the storage of water taken under groundwater, supplementary and general security access licences.
Floodplain harvesting is opportunistic and episodic, meaning that events do not necessarily occur every year. Because of the multiple uses for storages and the opportunistic nature of floodplain harvesting, on-farm dam storage capacity does not equate to historic or current annual use, nor to the volumes of entitlement that will be issued as part of the licensing process.
Historic and current use is being modelled using multiple lines of evidence. The entitlements issued as part of a floodplain harvesting water access licence will be based on this modelling to bring this activity back to the legal limits set under NSW water sharing plans and the Basin Plan.
Can I be confident in the department's data and reports?
The department is committed to full transparency and ensuring that all data, information and assessments relating to floodplain harvesting are well-documented and made available online.
Modelling and reports are developed using multiple lines of evidence and current, best available industry data. To assist implementation of the NSW Floodplain Harvesting Policy and development of water sharing plan rules, technical reports are developed for each valley.
The reports are peer-reviewed by independent experts, Greg Claydon and Tony Weber. They are experts in water industry reform, policy development and modelling, and are independent from the department and MDBA. The primary objective of their review is to provide transparency regarding technical information and provide stakeholders with confidence that technical rigour and supporting processes are suitable to support implementation of the NSW Floodplain Harvesting Policy.
Reports for the Gwydir, Namoi, Macquarie and Barwon-Darling Valleys are in development and will be released in early 2021.
How are legal limits defined and where do they apply?
The legal limits are not new, they exist in NSW water sharing plans (WSPs) and the Commonwealth’s Basin Plan. Allowable limits of water diversions in NSW are determined in WSPs under the NSW Water Management Act 2000.
WSPs set out rules for how water is allocated within a water source or group of water sources. These rules include limits on the volume of water that can be taken under licences and basic landholder rights. Limits on surface water diversions are established to keep floodplain harvesting levels at or below the long-term volume that was capable of being taken in the 1993–94 water year (the Cap).
Following accreditation of NSW water resource plans (WRPs) by the Commonwealth Minister for Water, WSPs will be amended to give effect to sustainable diversion limits (SDLs) specified in the Basin Plan.
Floodplain harvesting is a component of the limits set out in NSW WSPs. These limits, together with WSP rules, provide for the protection of flows in the river and on associated floodplains to ensure environmental outcomes and a level of reliability to downstream water users.
