NSW deputy premier John Barilaro was joined by Member for Myall Lakes Stephen Bromhead, MidCoast Council mayor David West, Manning River Action Group spokesperson John Kennewell and members of the Mid Coast business community in Taree on Wednesday March 3 for the announcement.

The business case, which will take about 18 months to complete, will include necessary technical studies, investigations, concept designs and community consultation.

It will also assess the Manning River Taskforce's recommendations for the project, look at any environmental and financial concerns and ensure the costs and benefits add up.

"For 140 years we've been talking about this river. We need a permanent navigable entrance," Mr Bromhead said.

"This is the important step, this is the last piece of the jigsaw we need so we can accomplish what people have been talking about for so long."

Funding will also allow Manly Hydraulics to model the potential solutions to the issues which have plagued the river.

The development of the project has sped up in recent times, which dates back to the establishment of the taskforce in 2019 to research the plausibility of permanent entrances.

"They've come up with some recommendations which they believe is the answer and will deliver what the community has wanted," Mr Bromhead said.

A specific cost for this phase of the project wasn't determined, but the government funding will cover the business case and model.

The overall project and its outcomes could cost up to $100m.

"That's a big commitment by the people of NSW and this community but it's something we've been fighting for so long," Mr Bromhead said.

"The scientists and experts agree this needs to be done and we're committed to getting it done.

"This is a generational transformation, this will transform the Manning Valley for the good."

Mr Barilaro didn't believe accruing a large sum of money for the project would be a challenge given the $4.2b Snowy Hydro Legacy Fund.

"It's about a future for Taree and the Manning," Mr Barilaro added.

"We know there's issues around flooding and making sure there's clean water for our fisheries and oyster leases.

"We want to do it right and be proud of this investment."

Meanwhile, Manning River Action Group spokesperson John Kennewell labelled the funding as 'a momentous step forward'.

He was surprised by how quickly the funding was secured in regards to the latest push for the entrances.

"It's outstanding the turn around from both council supporting it and the State government announcing the funding," Me Kennewell said.

"We've gone from the foundations to a snowball effect."

Mr Kennewell said the funding also confirmed all parties involved in the project are on the same page.

The Mid Coast community can be assured the Manning River Taskforce's recommendations for the project account for environmental and economic loss and sustainability of the river.

"Our community can move forward and benefit from the studies," Mr Kennewell said.