Federal-state tensions over water issues have escalated with South Australia demanding Barnaby Joyce, the federal Water Minister, drop his nomination of an irrigation lobbyist to the Murray Darling Basin Authority's board.

South Australian Water Minister Ian Hunter this month wrote to Mr Joyce to complain about his nomination of Perin Davey to fill one of two openings on the board overseeing implementation of the $13 billion Murray Darling Basin Plan.

At the time, Mr Hunter called the appointment "ill-advised" because of Ms Davey's record of "strongly advocating against the delivery of the plan".

Those concerns have been heightened by Ms Davey's apparent membership of a group of irrigation lobbyists given special briefings by Gavin Hanlon, a senior NSW water bureaucrat.