Four coal mines were given permission to release their legacy water into Queensland river catchments last November, now the Deputy Premier says they will all be allowed to dump excess water.

“Given the success of the pilot mine water release program over the 2012/2013 wet season, the Queensland government will be expanding the initiative this coming wet season to assist coal mines to return to full production," Queensland Deputy Premier Jeff Seeney said.

Independent water monitoring reportedly showed metal levels across the catchment were well below relevant water quality guidelines, the mines have had four pilot release opportunities leading to 8.5 gigalitres of water being let go since late January.

Mr Seeney said the current regulations did not allow mines to reduce the legacy water from past wet seasons. If that water was left to wallow, it would impact on mine production, royalties and water quality when it was released, the Deputy Premier says.