Water allocations face potential shake-up with climate review under way

The details a review into the water determination process were shared in a monthly webinar hosted by the Department of Planning Industry and Environment.

Director of inland planning Peter Hyde outlined the goal to integrate climate change into the process used to determine water allocations.

So far the focus is on two valleys - Border Rivers and Murrumbidgee - with a plan to expand out to the other valleys by 2027.

Mr Hyde said there was potential for climate change to impact on water allocations, the environment and much more.

He said the Millenium Drought and Tinderbox Drought (2017-20) had record low inflows after two-third of the state had their lowest rainfall on record.

"It led to the suspension of many water sharing plans," Mr Hyde said.

He said these droughts had severely impacted on the security of water at the time with Tamworth getting down to 20 per cent of its available water while other towns needed to switch to a back-up supply.

Mr Hyde said existing plans were calculated on the minimum inflows expected, based on the worst drought on record, which varied for different valleys.

He said this allowed them to ensure high priority water needs, such as town water supplies, were met before general security water was allocated.

"Climate change is a long-term impact but also climate change is variable," he said.

"We expect to see longer periods of drought - and more severe drought ... but after drought finished, there will be more rainfall.

"We do already factor climate change into a range of situations but we are facing more extreme circumstances."

He said the plan to include climate change modelling in the resource planning would mean more security for water users.

The proposed method will be reviewed by a panel of experts, expected to be completed in April, with consultation on the method and modeling results in each valley to follow.

"If we do need to change a water sharing plan, it will go through a review," Mr Hyde said.

He confirmed there was the potential for negative impacts on irrigators, depending on what the modelling found and what method was used.

NSW Irrigation Council chief executive officer Claire Miller said there had been little warning this change was happening ahead of the webinar.

"We are extremely concerned about this," she said.

"It is likely to lead to cut backs. There are multiple concurrent projects underway right now that could reduce people's access to water."

She said along with buybacks in the southern basin, the department was adding another project - "presumably without compensation".

Ms Miller said a previous, similar project in 2020, had modelling suggest allocations could reduce between 13pc and 25pc each year in the Lachlan Valley.

"That is why we're pretty alarmed," she said.

She said there was already availability in the determination system to operate in real time and respond to climate change.

"They could simply review the current system and see how it has performed for the past 20 years," she said.

Ms Miller questioned if there would be "genuine consultation" on any proposed changes or "just another webinar every few months".

She also questioned the timing of the review, saying it came as the department did not have the resources to do proper water sharing plans or other "core activities".