Mr Morrison pledged $180 million for the Hughenden Irrigation Scheme and up to $54 million for Hells Gates Dam Stage 1, promising "public probity requirements will also be met".

Mr Katter has now backed off on his threat to refer Liberal MP Chris Crewther to the High Court following Thursday's deal with the PM.

"Have they bought my vote? I'd say if they have, they've paid a bloody lot of money for it," Mr Katter told Fairfax Media. "I don't mind being used. The cunning of what he's done here is quite amazing."

Mr Katter said the PM had long wanted to make the irrigation investments, and discussions were underway. 

Mr Morrison, who met with Mr Katter in Townsville on his tour of Queensland, said the deal would "support the continued stability of the government" and protect it against "political disruption by the opposition".

READ ALSO: Hell’s Gate ‘within reach’

However Queensland Natural Resources Minister Dr Anthony Lynham has sought detailed information from the Federal Coalition about its dam plans.

“We are always keen to see federal money heading for Queensland,” Dr Lynham said. “We are just not sure what is expected of any Queensland government or statutory bodies. The Palaszczuk Government has funded an initial investigation into the Hughenden Irrigation Project with Flinders Shire Council and an initial business case of the $5.35b Hells Gate project has identified significant challenges”.  

Dr Lynham said detailed business cases were conducted by independent bodies like Building Queensland, before governments committed to major, long-term infrastructure like dams.

“I have written to Federal Water Minister David Littleproud asking for any further information on the nature or scope of these projects, the process to advance these projects, including detailed business cases and appropriate environmental assessments who will operate these assets.”

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