Queensland's Supreme Court has dismissed a community group's bid to stop the expansion of Adani's Abbot Point Terminal.
Whitsunday Residents Against Dumping (WRAD) unsuccessfully argued the Department of Environment and Heritage Protection's approval of the expansion was not legally granted.
Spokeswoman Sandra Williams said the court's decision was a setback for the Great Barrier Reef, which is already under threat from the effects of climate change.
"Today is a dark day for the reef," Ms Williams said on Thursday.
"Make no mistake, if this destructive project goes ahead it will cause irreversible damage to the Great Barrier Reef and the 70,000 jobs the reef supports."
Environmental Defenders Office Queensland chief executive Jo-Anne Bragg said WRAD would consider what options were available to them given the court's decision.
Construction on Adani's $21.7 billion plan to build Australia's largest coal mine in the Galilee Basin and connect it to Abbot Point via a 31.5-kilometre rail line, is expected to start next year.
Adani has been contacted for comment.
