A former Queensland government water chief says the government has "no clue" what Adani's mine and others will do to the state's underground water sources.

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

Possible impacts on groundwater supplies to areas like the ancient Doongmabulla Springs, south-west of the proposed Carmichael mine, remain a hurdle for Adani. Credit:Tom Jefferson (Lock The Gate)

He says the government has been telling people the state's underground water stores are being managed sustainably.

But in truth it has no idea of the cumulative impact if all nine Galilee basin mine proposals, including Adani's, proceed.