The nine core farmers are seeking damages to the tune of $750 million from the federal government's agency.

Moulemain farmer Darcy Hare has joined the push and explains the cost is an estimate combined total figure, assuming $1000 for each hectare of land rendered insufficient due to the "mismanagement of the river systems over the [past] year."

"For two years straight we've had zero water allocations," Mr Hare said.

"We're looking like we're going to be saddling for another year of zero allocations, so we wanted to get this in before the end of the [irrigation] year.

Mr Hare described feeling as they the towns between Murray damming sites where becoming second-class citizens, as water allocations are increasingly sent to South Australia to ease the pressure of a non-flowing Darling River.

"We've been treated like absolute hicks out here," he said.

"It's not our fault it isn't raining, why should we have to foot the cost of it? We can't keep doing the heavy lifting for this basin plan."

Mr Hare and the coalition of farmers are alleging systematic mismanagement of the river system and joining lake networks.

They also claim the MDBA drained the Menindee Lakes in 2016 while knowing it would leave little water for the southern systems.

The plight of the Menindee and Lower Lakes was recently brought back into national headlines last summer, when millions of fish washed up dead along the nearly-dry system.

Furthermore, instead of sending the full flow to use across the three states, they say the water was left to overflow and become unusable.

In the past year, they say there has been 141 days of flooding which has caused significant loss to finances for those who depend on the water system for their income.

"They brought in 'overbanking'," Mr Hare said.

"We estimated there's been a loss of about 850 gigalitres of water that's been flooded out into the forests."

Without reviewing this system, Mr Hare said the problem will only be exasperated in the future.

"By 2025 we've been saying we're going to need about 1500 gigalitres just for almonds in our region," he said.

"To put that in a bit of perspective, that's about half the capacity of the Hume dam, but it's below the choke so most of it will end up in the forest. It's unreasonable."

The action follows widespread protests across the southern Riverina last month as farmers called for the government to 'pause the plan' by June 30.

"All we're asking is for a policy to be made that keeps [water] in the channel capacity and avoids the losses."

The government will now have 28 days (beginning the date of filing on Tuesday) to respond to the lawsuit.