Raking of the Tamar River estuary has stopped due to it being less effective than predicted, the City of Launceston council says.
The sediment, which is often seen on the Tamar River when the tide is out, was last raked earlier this year.
At the council's meeting next week, it will discuss a report that showed most of the sediment moved through raking has settled in the estuary's navigational channels.
The council is expected to look into going back to dredging the river, which has worked in the past, despite it being more expensive.
The Tamar Estuary Management Taskforce separately commissioned the Trevallyn Flow Releases Study in 2018, to evaluate the ability of water releases from Trevallyn Dam to remove sediment from the upper estuary, both with and without sediment raking.
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This study demonstrated that even a release of all the water in Trevallyn Dam down the South Esk River would have a negligible effect on silt mobilisation.
According to the study, releasing all the water in Trevallyn Dam would cost Hydro Tasmania about $100,000 in lost electricity generation. With raking, the total cost would be closer to $190,000.
Even then, sediment returns within three months.
NRM North chief executive Rosanna Coombes said the incoming tide in the upper estuary is stronger than the outgoing tide.
"This results in a normal pattern of sediment collecting in the upper estuary," she said.
"Naturally high-flow events, such as flooding of the North and South Esk, are significantly more effective at mobilising sediment than targeted releases of water through the dam.
"The June 2016 flood event removed 160,000 cubic metres of sediment from the Yacht Basin. The highest modelled water flow release from Trevallyn Dam can be expected to move 10,000 cubic metres from the mudflats."
Hydro Tasmania's Jesse Clark, welcomed the research and said that it was important to understand the effectiveness of the options before committing to a course of action.
The council meeting will be held at 1pm on Thursday, October 17 at the Town Hall.
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