Almost all Murray-Darling Basin catchments staying within water limits: audit

The Murray-Darling Basin Authority conducted the first audit of the states' Sustainable Diversion Limit (SDLs), which dictate how much water can be used by communities, industries and farmers.

The MDBA found a 97 per cent compliance rate across all states, with just three of the 109 SDLs not within their limits, all within NSW.

MDBA executive director Tim Goodes said the high compliance rate across both surface and groundwater was "great news".

Barwon-Darling surface water, the Upper Macquarie Alluvium and Lower Murrumbidgee Deep groundwater areas were above their water plan's allowable limits.

"These findings don't mean there have been individual compliance issues or breaches in water use - this is about water planning and use at a catchment level," Mr Goodes said.

For the two groundwater catchments, the MDBA found NSW's reported reason for the exceedances to be valid. NSW has already applied a restriction on water take in one of these areas in 2020-21 and is talking to communities about how to apply these in future.

For the Barwon-Darling surface water area, the NSW claim for reasonable excuse was not accepted.

The MDBA found in the Barwon-Darling, NSW had not fully implemented its rules for take outlined in its draft water resource plan, which includes assessing compliance with their state limits.

"This is an important rule to ensure actual take does not exceed the allowable limits," Mr Goodes said.

Separately, NSW said its model needs further work.

"The Barwon-Darling model is 20 years old and is based on diversion data from old meters, it hasn't been recalibrated to reflect the new meters being rolled out," Mr Goodes said.

Despite the issues, MDBA acknowledged NSW had undertaken significant work to meet SDL compliance standards.

"NSW has worked cooperatively with us, and outlined its plans to improve, and we are pleased that they will publish information about compliance with their state limits," Mr Goode said.

"We have also asked NSW to re-double efforts to deliver on a range of existing commitments that relate to the measurement, management and regulation of water resources."

In the future, the newly established MDB Inspector-General will be responsible for compliance audits and reports.