In 2012, The Murray-Darling Basin Authority (MDBA) introduced sustainable diversion limits (SDLs) as part of the Basin Plan. Since 1 July 2019, SDLs have balanced consumptive use with water for the environment.
The consumptive uses of surface and groundwater support agriculture, industries, cities and towns. But it was clear that the increases in consumptive use had environmental impacts. This was also evident in water quality issues and shortages.
SDLs make water available for the environment but has some flexibility for consumptive use.
They limit the volume of water taken from each of the Murray-Darling Basin’s water areas. The Basin has 29 surface water areas and 80 groundwater areas. Basin states calculate a long-term average annual volume that each area can extract.
Sustainable diversion limit compliance
Each year, Victoria reports on compliance against the SDLs. The MDBA publishes these reports following each water year.
SDL calculations depend on many complex factors and datasets. The Department of Energy, Environment and Climate Action (DEECA) collects water data with many water agencies.
This data informs 2 figures:
- annual actual take
- annual permitted take for the preceding year.
Actual take is the volume of water actually taken from waterways in a given water year. Metering is the most important data input for this figure. If metering data doesn't exist, DEECA and its agencies will make an estimation.
Permitted take is the annual limit corresponding to a catchment's SDL. This is the volume allowed to be taken from a river system for consumptive purposes in a given water year. It is calculated retrospectively.
Computer-simulated models representing Northern Victorian water resource systems are updated with climate and streamflow data. These models are used to determine the annual permitted take under the climatic conditions experienced in that year.
The volume actually taken in the year is compared against the volume of annual permitted take to determine whether each system is compliant with its SDL.
Page last updated: 08/09/23