The State of the Climate report prepared by Bureau of Meteorology and CSIRO indicates that winter and spring rainfall is projected to decrease.

The same modelling indicates extreme rainfall events will become more intense.

Lachlan Valley Water chair, Tom Green, says it is extremely important in those extreme events the Lachlan Valley can store more water.

"We have just seen reliability is a challenge," Mr Green said.

"Where we went from widespread flooding in 2016 to water restrictions having to be introduced in July 2019 as inflows were insufficient to provide enough water to meet the demand for operational, environmental and irrigation needs in the valley.

"This saw irrigation and environmental flows reduced when they were most needed during drought conditions."

He says if the dam wall is raised it'll be a "win for everyone".

"We will see on average 21,000 megalitres per year of extra water available to the valley, and one of the really important pieces of information we need is what this 21,000 ML/year equates to in timing and volume," he added.

"Agriculture is changing in the Lachlan as we see more high value crops, expansion of horticulture and intensive dairy farming, and these developments can take place with the knowledge that there will be enough water during those drier years."

Mr Green also noted during those extremely dry periods in the region an expanded, higher wall at Wyangala will mean a greater amount of water for the environment.

"The last thing we want to see are the fish kills which occurred along the Darling River during the last drought. The dam wall raising greatly reduces the chance that it will happen along the Lachlan Valley," he said.

"The project is a win for everyone and it is important that it proceeds to help underpin a sustainable future for towns, farmers and the environment."

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