A billion-dollar package to upgrade or build new dams in drought-afflicted NSW regions is expected to put "bulldozers in the ground" next year, the Liberal-National coalition has said.

Key points: The projects were expected to begin in 2020 and be completed by 2025

The projects were expected to begin in 2020 and be completed by 2025 On Thursday, the NSW Government signalled it would fast-track applications to reduce delays

On Thursday, the NSW Government signalled it would fast-track applications to reduce delays An environmental group has slammed the idea of accelerated applications for the projects

Australian Prime Minister Scott Morrison and NSW Premier Gladys Berejiklian on Sunday announced a joint investment between the federal and state governments for "priority large-scale water infrastructure projects".

Up to $650 million has been flagged to upgrade the Wyangala Dam in the state's central west and $480 million will go to the new Dungowan Dam near Tamworth.

The Wyangala upgrade includes raising the dam wall by 10 metres and Dungowan will be the first new dam in NSW for more than 30 years.

"These projects don't happen overnight but we're working as quickly as possible to get all the necessary work done so we can start digging," Mr Morrison said.

The $1 billion package will be split evenly between the NSW and federal governments. ( ABC News: Caitlin Furlong )

Ms Berejiklian said she was confident construction would begin in 2020 and hoped works would be completed by 2025.

"What was missing in the past, was the funds to accelerate the project," she said.

"For too long it's been talked [about] ... it's not just the funding, it's the political will and when you get a Federal Government backing what you're doing, that gives us the impetus and the momentum to keep pushing forward."

NSW Deputy Premier John Barilaro said he was "confident that in the next 12 to 15 months we'll see the bulldozers in the ground".

However, the NSW Opposition said the Government should be focusing on more immediate solutions such as pipelines and bore drilling.

"Talk of dams from this government after eight-and-a-half years of not doing anything is a convenient distraction," NSW shadow minister for water Clayton Barr said.

"If you are west of the divide in NSW at the moment your concern isn't about a dam, your concern is about water today and tomorrow."

$24 million is also being invested in the proposed Border Rivers project on the Mole River, near the Queensland border.

Guyra's water reserves dried up earlier this year. ( ABC News: Caitlyn Gribbin )

NSW Planning Minister Rob Stokes signalled on Thursday he would be taking charge of dam applications and would declare them critical, "state-significant" infrastructure to be fast-tracked for development.

Mr Stokes said he would personally sign off on applications, bypassing delays brought about by the Independent Planning Commission.

The head of the Nature Conservation Council, Chris Gambian, said he was worried about losing the usual checks and balances around these dam projects.

"Bypassing biodiversity assessments is only going to make the problem worse," he said.

"It means that you could build a piece of water infrastructure without paying any attention to what that means for the health of the river."

Mr Gambian said those assessments exist to prevent things like the fish kills seen earlier this year in Menindee.

"We've already seen a devastating summer last summer," he said.

"We think this summer is going to be even worse."