Case study: How much water should we be taking from our rivers

Maintaining river health

The Murray-Darling Basin Plan sets limits on how much water can be taken from the Murray-Darling Basin to maintain river health. Without these limits, water use would increase and there wouldn’t be enough left for the environment. The Basin Plan aims to ensure that water is shared between all users and the environment.

Water Resource Plans set out the method for finding out how much water we can take from northern Victorian waterways every year. This volume is called the permitted take. The permitted take is how much we can take from our rivers so they can stay healthy.

The permitted take is different from year to year. It depends on the weather conditions that affect how much water is available and how much water we need.

How is permitted take calculated?

Hydrological models are used to calculate the permitted take from regulated rivers. They consider the weather over the past year and how much water was available to users. They then calculate what the sustainable level of use would have been under those weather conditions. This includes the water demands of farms, industries and towns.

The total volume used in the model for that year is the permitted take – that is, how much water could be used or diverted away from the waterway at a sustainable level. This modelled number is then compared with the amount of water that was actually used in that year.

These calculations allow Victoria to track how much water we use over the long-term relative to the Sustainable Diversion Limits.

Sustainable Diversion Limits

When assessed as an average over the long-term, the permitted take is called a Sustainable Diversion Limit or SDL.

SDLs are the main way that the Murray-Darling Basin Plan limits consumptive water use in the Basin.

Hydrological models allow us to assess our compliance with SDLs. Victoria must report on this compliance following the end of each water year.

Page last updated: 11/09/23