DEBATE on whether to build a dam on a tributary of the Mitchell River in East Gippsland is again threatening to expose old tensions in the Victorian Coalition.

Lindenow irrigators are campaigning for a dam on the Wentworth River, a tributary of the Mitchell, to eliminate pumping interruptions during dry spells.

Federal Gippsland MP Darren Chester triggered fresh debate on the issue last month when, in a statement, he said: "No one's talking about a dam on the Mitchell River but we should be taking a closer look at opportunities for a small storage on a tributary of the river."

Speaking in Parliament last week, Victorian Water Minister Tim Holding accused the Nationals of making a secret deal with irrigators.

"We reject the secret proposition that ... is being sold to these irrigators by the Member for Gippsland, who on the one hand says one thing publicly and on the other hand says privately that a 20 to 25 billion litre storage on the Mitchell River would not have devastating consequences," Mr Holding said.

The Victorian Coalition has so far refused to reveal whether a dam will be part of its water policy ahead of the November 27 election.

Yet one senior Liberal has already ruled it out completely.

Member for Eastern Victoria and former Opposition Upper House leader Philip Davis told The Weekly Times on Monday that "as far as the Liberal Party goes there will be no dam on the Mitchell".

Mr Davis said this also meant no dam on the Wentworth or any other tributary of the Mitchell because "as far as I am concerned a river is the entirety of its catchment".

When asked whether he could rule out a dam on a Mitchell tributary, Nationals deputy leader and Coalition water spokesman Peter Walsh would only say: "I'm not in a position to talk about policy at this stage and we have already ruled out a dam on the Mitchell."

Mr Davis denied the issue was inflaming tensions within the Coalition.

"There won't be tension," he said.

"This is what you call a policy debate. If you have two policy options and one is poor public policy ... you choose the one that is better public policy."

Mr Davis also said Mr Chester had put Mr Walsh "in an awkward position" by commenting on a state issue in the first place.

Lindenow irrigator Ross Ingram said restrictions on pumping from the Mitchell River were threatening farmers' viability.

"We don't want an extra allocation, we just want somewhere to store the water we are already entitled to," Mr Ingram said.