Thursday 14 April 2005
SILT - UPPER TAMAR RIVER
Mr FINCH (Rosevears) - Mr President, the continuing debate over what to do about the silt problems in the upper reaches of the Tamar River has intensified in recent weeks and I would like to take this opportunity to bring some of the arguments to the attention of this House.
Ms Thorp - Launceston council will fix it.
Mr FINCH - No, the greater northern council.
It would seem that the only thing that everyone can agree on is that silt in the upper Tamar is a subject of great concern. There seems to be as many opinions on the cause and the cure as there are dredge loads of silt to be removed. However, a meeting of the Upper Tamar River Improvement Authority, UTRIA, in Launceston on 6 April, to which you, as the member for Paterson, Mr President, also our member for Windermere and myself were kindly invited to attend, did a great deal to improve our understanding of the issues and the arguments.
The fact that the problem of the silt in the river continues to evoke those regular letters to the editor of the Examiner is evidence of a great deal of community concern about this issue. One opinion continually expressed, Mr President, is that dredging is not a long?term solution and I think everyone agrees with that. UTRIA itself acknowledges that dredging is a stopgap measure. It says that until someone comes up with a better solution, dredging is really the only way to prevent the silt getting the upper hand. UTRIA does an outstanding job with limited funding that comes from the State Government and from the Launceston and West Tamar councils. They do what they can afford to do. There is consensus that the ideal way to deal with silt deposits is through a natural water flow. Therefore we have the Hydro being blamed for altering the natural flow down the Cataract Gorge. But it must be realised that all the Hydro does is divert some of that flow through its Trevallyn Power Station and into the river, only a relatively short distance downstream. Is this really the only cause of the problem?
Our meeting with UTRIA, Mr President, gave me a new understanding of the cause of the problem, although, I hastily add, no better idea of a cure. Silt, carried down the North and South Esk rivers, seems to be carried down the Tamar on the top of the river until it is dropped out by suspension when it meets the salt water. It is then brought back up the river by tidal movements beneath a layer of that fresh water that is moving downstream. The silt drops to the riverbed at Launceston and builds up until the winter flows or dredging moves it. The estimate is that 30 000 cubic metres a year are deposited in the upper reaches. At this stage we have three potential solutions: stop the silt coming down the North and South Esk in the first place, stop incoming tides bringing it back to the upper reaches, or find some natural means to flush the silt down river again.
It would seem to me, Mr President, that the ideal solution would be the first. It was suggested at the meeting by Bill Woods that rural activity and forestry operations are contributing to the amount of silt entering the Tamar. Certainly, more silt seems to be entering the river now than before European settlement. The only way to stop incoming tides bringing the silt back up the river would seem to be a barrage with a loch. It is an expensive option but one which might have to be considered. I have spoken about that in the House before. I have floated the idea before, for that barrage to be at Stephensons Bend, near the Grammar School. I have received a new suggestion that it should in fact be further downstream near Tamar Island. But as far as finding a natural means to flush the silt away is concerned, this can also involve very expensive works. We really do not want to keep flushing northern Tasmania's topsoil into Bass Strait.
We have had numerous studies to try to ascertain exactly what is going on with our river, without a magic outcome. One study is progressing as we speak and should come up with a result at the end of this year. It is looking at four main elements: the outflow from the Trevallyn Power Station, what is happening in the Ti Tree Bend part of the river where there is a waste treatment plant, the dredging regimes and also natural scouring. On that last point, the natural scouring, it has been suggested that we are waiting for our next 100-year flood. We may have to wait until 2039 to see that silt washed into Bass Strait, with perhaps some of Invermay.
As I suggested earlier, Mr President, the best solution might be to keep our topsoil where it is, prevent it being washed into the Tamar and prevent the silt problem from happening in the first place. Time and effort by bodies like UTRIA will tell. In the meantime, it is encouraging to see so many people concerned about the problem and engaging in arguments about potential solutions. It was also encouraging early this week to see 20 pelicans at Tailrace Park - an encouraging sign that the river is in fact healthy.
Mr Aird - Pelicans bring you good luck.
Mr FINCH - And they are very tasty too.