Senator Susan McDonald has slammed the Queensland Government for "demonising" farmers and imposing overly harsh restrictions on them.
Senator McDonald was instrumental in establishing a Senate Inquiry last year into the evidence used to impose water quality targets on cane and cattle farmers.
The Inquiry found the State Government had ignored the fact farmers were already altering their practices to reduce environmental impacts.
It also stated run-off from land mainly affected "just three per cent" of the total Great Barrier Reef area.
The latest water quality report card showed significant improvement, with nitrogen run-off into the Great Barrier Reef Lagoon dropping 25.5 per cent since 2013.