A former Nationals MP has called on the party to push for a royal commission into water management.

Former MP Kay Hull says the management, control and transparency of water trading needs a major inquiry.

“I would be advocating for us as the Nationals to lead that,” she told AAP.

“There has been calls for a royal commission into water and as a past person who has represented irrigation I would absolutely support that.”

Ms Hull said authorities need to examine whether water trading is open to fraud.

She believes the Coalition is disinterested.

“I don't know that they're resisting. I think the case for the royal commission hasn't been articulately packaged together to give a clear understanding,” she said.

Ms Hull has been handing out how-to-vote cards for her successor in the NSW seat of Riverina, Nationals leader Michael McCormack.

Mr McCormack has previously rejected calls for a royal commission.

Ms Hull said voters were feeling “emotional frustration”, which will be felt by the Nationals in heartland seats.

“It's very difficult circumstances and time in the bush,” Ms Hull said.

“The effects of the millennium are still being sourly felt in our electorates.”