The irrigation industry has confirmed it lobbied the Conservation Minister Nick Smith over Fish and Game's use of controversial billboards in Canterbury that link irrigation to poor water quality.
Fish and Game has a statutory right to advocate for fresh water.
It's been at loggerheads with Federated Farmers since it launched its dirty dairying campaign in 2002.
According to Fish and Game, Dr Smith recently threatened the organisation with restructuring because he was angry about the billboards.
Dr Smith denied the accusations.
Irrigation New Zealand chief executive Andrew Curtis has confirmed it had been in touch with the Minister over the billboards.
"We wrote a letter to the Minister, it must be 15 months or so ago now, because we were very concerned about the posters that had been put up by Fish and Game.
"We were questioning whether they were going beyond their statue, by going that far. We didn't think those posters were very helpful."