The Queensland Government has put a stop to work on an underground pipeline after the release of drilling fluid into the Condamine River on the Western Darling Downs.

Contractors for leading Australian coal seam gas explorer QGC notified the Environment Department of the incident earlier this week.

Environment Minister Andrew Powell says initial reports suggest it has had no significant impact on water quality as contractors took steps to contain the spill and pump it out of the river, downstream of the Chinchilla Weir.

He says work will not resume until the department is satisfied the operation can be undertaken without further impact.

But Lock the Gate Alliance spokesman Drew Hutton says that is not the point, and the incident is of great concern.

"Too few of the people involved in the drilling operations just simply aren't trained adequately for the job, so we'll continue to be having these many small incidents which together will create a cumulative impact which is unacceptable," he said.

QGC says there has been minimal impact from the inadvertent release of drilling fluid into the Condamine River on the Western Darling Downs.

A spokesman says the drilling fluid contains clay and water to lubricate the drill bit and that it was quickly contained and pumped out of the river.

An Environment Department spokesman says the landholder involved is comfortable that the incident has had minimal impact on water quality.