All of a sudden this week, national attention focused on a simple truth that had been hiding in plain sight.

Scott Morrison can only form government – and remain prime minister – if the National Party backs the Liberals in Canberra.

That suddenly matters so much more now that Barnaby Joyce has taken over the National Party and become Mr Morrison’s deputy.

The same Barnaby Joyce who did everything he could to sabotage downstream states as water minister – saying SA didn’t “have a hope in Hades” of getting the water the river needs to survive.

Mr Joyce was put back in charge of the Nationals to drive a harder bargain within the Morrison government. And they wasted no time before moving amendments in parliament to scrap the requirement to deliver 450GL of water promised in the Murray Darling Basin Plan.

They also accidentally released internal briefing notes contemptuously claiming “the science no longer supports SA needing fresh water”.

It’s obvious that as long as Mr Joyce has power to cut deals at the highest levels of government, SA’s water security and the health of our river is in danger.

The fear is what Mr Morrison would do if he had to choose between protecting downstream communities or keeping the top job by giving Barnaby Joyce what he wants.

When I was water minister trying to broker agreement over the blueprint for a sustainable future that eventually became the Plan, Mr Joyce and his supporters fought me every step of the way.

But now, Mr Morrison thinks he’s on a political winner with Barnaby Joyce, saying his new deputy is “a wind in the sails”. That’s a bad omen for SA. We know which way the wind is blowing.

Mr Morrison has to spell out how he will deliver the water promised to the Murray in full – and on time.

This Opinion Piece was first published in the Sunday Mail on Sunday 27 June 2021.