Adani finally has the last approval it needs to begin building its new coal mine in Queensland.

Queensland's environment department has signed off on a plan to manage groundwater on and around the company's Galilee basin mine site.

That is despite enduring concerns held by some water experts that the mine could kill off an ancient springs complex, and have dire effects on the health of the Carmichael River.

Adani promised an immediate start to construction once the last approval was in hand.

'An important step for us'

Adani mining chief executive Lucas Dow said he was looking forward to starting work on the future mine. 

"This is a great day for our project but also regional Queensland and North and Central Queensland," he said, in a press conference Thursday afternoon after the company received final approval.

"So we are now focused on getting on with the job and we want to say a big thank you to all of those folks who have stood beside us, particularly those in North and Central Queensland.

"It is now a case of us getting on and delivering on a promise."

Mr Dow said preparation works will shortly be underway to ensure safety protocols and environmental requirements are met. 

'Rigorous assessment'

In a statement, the Queensland Department of Environment and Science said its decision had been based on a "rigorous" assessment.

"Adani submitted its most recent version of the plan, addressing the department's feedback, yesterday," the department said.

"The (plan's) assessment has been rigorous and based on the best available science."

The department said it was satisfied Adani had identified the source of the main aquifer of the Doongmabulla Springs Complex as the Clematis Sandstone.

Adani commits to additional safeguard measures

The approval commits Adani to additional measures to safeguard and monitor water sources.

Some water experts claim Adani has grossly underestimated the mine's impacts on the underground, and fear the effects of its permit to pump water out of the mine to allow for the safe extraction of coal.

Hydrologists from four Australian universities issued a joint report earlier this week, saying Adani's water science was "severely flawed".

They warned the mine could have a such a dramatic effect on groundwater levels that the ancient Doongmabulla Springs Complex, 8 kilometres from the edge of Adani's mining lease, could permanently dry up.

That would spell death for the plant and animal species that rely on the springs for survival, one of those experts, Flinders University hydrogeology professor Adrian Werner, told AAP.

Prof Werner also warned of dire consequences for the Carmichael River which flows through the mine site, saying it would be cut off from its flood plain and could be robbed of groundwater that keeps the river flowing for much of the year.

Before Thursday's decision, a former state government water chief said Adani's plan would have irrefutable consequences for underground water sources in an area that's heavily dependent on them.

'No clue of cumulative impact'

Tom Crothers is a former general manager for water allocation and planning in the Queensland Department of Environment and Resource Management.

Mr Crothers, who's now a water policy consultant, said the state government had no clue what the cumulative impact would be if the Adani mine and eight others planned for the Galilee basin went ahead.

"We're looking at extraction of four Sydney Harbours out of underground systems. That's a huge amount of water," he told ABC radio.

"We see politicians put their hands on their hearts and tell Queenslanders that we're managing our groundwater resources sustainably.

"They don't know ... the Queensland government doesn't have a clue what's happening in terms of how underground water is being managed."