DREDGING the Clarence River as flood mitigation would be costly and ineffective, according to the flood models.
Clarence Valley Council director of environment, planning and community Des Schroder said while the Department of Crown Lands controlled the dredging of sand and sediment from the river, the council's flood models showed dredging would have a minimal effect on flood heights.
"The most important controlling element is what happens down river and out to sea," he said.
"The high tide height and timing is one of the most critical factors in flood control for us."
Mr Schroder said he was aware of public opinion the river had silted up and required dredging, but said this would be prohibitively expensive as well as ineffective.
Last month, Dovedale resident Ken Weks wrote to council to voice his fears the build-up of sediment in the river since large-scale dredging stopped in the Clarence River was exacerbating flooding problems.
In reply, the council informed Mr Weks the decision to dredge was out of its control and Crown Lands had placed restrictions on dredging in the river.
"Sedimentation along the river will be an ongoing issue," the letter said.
Mr Schroder said dredging posed environmental problems, including damage to sea grass areas and other fish habitat.
He said dredging would continue around the river mouth to ensure the viability of the Port of Yamba and Boral would continue to dredge sand for its commercial use.
The Pacific Hwy upgrade works could also create demand for more river sediment, but nowhere near the amount needed to affect flood levels.
During a period up to the 1970s, five or six dredges regularly worked in the Clarence River.