That is the sentiment from the Ricegrowers' Association of Australia, which is concerned the reliability of general security entitlements in the Murrumbidgee and NSW Murray valleys will be permanently reduced if the motion is implemented.

RGA president Rob Massina said the motion has been put up as a private members bill in the NSW Parliament's Upper House.

"This was passed (last week), but that doesn't necessarily mean it will be instigated ... it still has to go through the Upper and Lower House," he said.

"From a local perspective, the Shooters, Fishers and Farmers Party have supported the bill.

"Given our local member (Helen Dalton) is part of that party, hopefully she understands the impacts of what a bill could mean for irrigators in the southern basin.

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"Since the Millennium Drought, the NSW government has put aside drought reserves above and beyond, so is there really a need to push that through?

"We would encourage (Helen Dalton) to talk to us about understanding the issues better for her constituents."

The motion seeks to update modelling to take into account more recent droughts to protect town water supplies.

In the NSW Murray and Murrumbidgee valleys, this means factoring in the worst years of the Millennium Drought.

However, multiple drought reserve accounts were already established in the NSW Murray and Murrumbidgee valleys following this drought precisely to protect town water.

Ms Dalton said while her party supported the bill, she wanted to clarify her position.

"For a start, the motion was passed in the Upper House - which is not where the government sits," she said. "This means it has no impact on legislation or any water sharing plans.

"My party ... supported the general principle that we should not hide information or exclude years of data when making decisions.

"We do not support a worst-case scenario as the exclusive basis for making decision. We do not agree with everything the Independent member who moved the motion said. There should be no one-size-fits-all approach to water sharing plans.

"I have urged the NSW government to delay the signing off on the plans until there is proper consultation with communities and the findings of current water inquiries are publicly released."

The RGA said NSW government management plans developed since do further mitigate the risk.

"So, all the motion does is reduce the volume of water available on paper to allocate for growing food and fibre, without making any difference to security of supply for towns," Mr Massina said.

He said the motion "will inevitably lead to less water for general security allocation because the model will assume another Millennium Drought is always around the corner".

The motion was proposed by Independent NSW MP, Justin Field, and supported by NSW Labor, One Nation, the Shooters, Fishers and Farmers, the Animal Justice Party and the Greens.

"These politicians have either chosen to ignore the risk to regional economies, or are otherwise seeking a political win, at the expense of our general security allocation and irrigators," Mr Massina said.

"Thankfully the NSW Minister for Water is not required to act on this motion per se, and the RGA has written to the minister to make it clear that our growers, industry and communities cannot support these proposed changes."