The Australian Democrats today laid the blame for the black plumes of pollutants at West Beach solely on the state government.

"The state government’s conflict of interest as joint venturer and environmental monitor has seen the fast tracking of the Holdfast Shores and West Beach developments," said Mike Elliott.

"Now we are seeing the environmental cost of this conflict of interest.

"The dredging responsible for the plumes are a consequence of the form of development approved by the state government.

"The state government was warned long ago about the environmental threat of these developments, but it went ahead with its plans anyway.

"Studies throughout the nineties revealed that the Adelaide coast from North Haven to Seacliff is not suitable for boat harbours because of sand movement patterns.

"Now we see sand building up faster than the trucks can shift it out and pollution billowing off our metropolitan coastline.

"With huge blow-outs in dredging costs and with dredging mobilising more pollutants the state government’s environmental and economic incompetence is the only thing that is crystal clear."