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Tamar Lake

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24.01.2022 Cataract Gorge Flows I am totally in support of Alan Birchmore, as I am sure does most of the community, in wishing to see greatly increased permanent flows down the Cataract Gorge to restore the aesthetic presentation both for residents and tourists. A permanent flow of 20 cumecs would be sufficient. The maximum flow down the penstock from Lake Trevallyn to the power station is 90 cumecs; however, from data provided by Hydro Tasmania, the average monthly flow through the pow...er station for the period January 1, 2010 to September 1, 2016 was 54 cumecs as it is a run of the river power station and the lake has almost no excess storage capacity. This is consistent with an average power generation of only 56 megawatts from a total installed capacity of 95.8 megawatts. This represents only 4% of the current total 2600 megawatts of installed hydro electricity generation for the State. Hydro Tasmania is aggressively promoting a project called Battery of the Nation that is designed to double the power generation in the State to 5200 megawatts using a combination of wind power and pumped hydro technologies. This is a fantastic project as it uses the national competitive strengths of the state in wind and water to boost the State’s economic advantage. This strategy by Hydro will reduce their reliance on Trevallyn and enable the permanent release of 20 cumecs down the Gorge while still having the capacity for full power generation when South Esk flows exceed 110 cumecs. See more

23.01.2022 Ian Kidd (letters Examiner 10th March) refuses to recognise the results of the very extensive sediment modelling studies carried out by WBM for Tamar Lake Inc. To quote from their reports, in a Tamar Lake scenario there will be a net export of sediment out of the lake over time, and modelling of sediment accumulations below the barrage at Point Rapid shows that, provided the freshwater is released on an ebb tide twice per day, there is minimal sediment accumulations over a 12 month period between the barrage and Low Head. Tamar Lake has no argument with the fact that if the freshwater is released on a flood tide, as was assumed in the WBM review for TEMT, there would be increased accumulations in this area.

22.01.2022 Economic Benefits The formation of a freshwater Tamar Lake with a barrage separating the freshwater inflows of the North and South Esk rivers from the estuarine tidal flows from Bass Strait will have an enormous positive impact on the economy of Launceston and the whole of Northern Tasmania. The studies carried out for Tamar Lake Inc. by KPMG (2014) forecast that for an investment of $500m in the barrage there would be an increase in Gross Regional Product (GRP) of 10% in the... 15 years post barrage construction, with 890 jobs in the construction phase and 1000 new jobs principally in the agricultural and tourism sectors. AECOM forecast that with the construction of Tamar Lake and the resultant boost to economic growth, land values of vacant and developed properties overlooking the lake in the area from Legana to Launceston to Dilston would appreciate by at least $1.5b; more than justifying the investment in the barrage. Using Value Capture funding methodology, which is very popular for infrastructure development in the USA, AECOM forecast that 50% of the investment could be privately funded. In addition to the boost from general economic growth, a substantial portion of the State and Local government contribution would be justified by increased property taxes; land taxes, stamp duties and council rates. With clear, clean, mud free freshwater in the lake with a minimum navigation depth of 5 metres from Low Head to Seaport, 24 hours per day, the Tamar would become the aquatic playground our senior citizens ‘remember’ from early post WW2 days. In summary, in addition to the lake becoming a net exporter of sediment from the Upper Reaches and the barrage providing an effective barrier to sea level rise in the low lying areas of Launceston, the Tamar Lake project will provide a major boost to the economic and lifestyle benefits on Northern Tasmania.

22.01.2022 Tamar Lake Inc. is pleased to announce the appointment of Sam Tucker as President Elect. Mr. Tucker is the Principal of Commercial Project Delivery and has been responsible for managing the construction of such iconic projects as the Charles Hotel and Apartments, the Penny Royal Redevelopment, and the floating Brooke Street Pier in Hobart. Please join us in welcoming Sam Tucker to the Tamar Lake Inc. Executive Team.

21.01.2022 TEMT Sedimentation Report The TEMT Sedimentation Report recommends hydraulic modelling to assess the flows necessary to deliver improved sediment mobilisation. Everyone would like to see say 20 cubic metres per second down the Gorge and no doubt in a tidal environment it would reduce sediment build up in the Yacht Basin. However I feel very strongly that the scope of this modelling should extend along the full length of the Upper Tamar from Freshwater Point to the Yacht Basin.... With the most recent report on the subject (Hydrodynamic Modelling of the Tamar Estuary August 2009 R.B 15279.02 prepared for the Launceston City Council by BMT WBM) showing that the mean supply of sediment from the South Esk catchment is 39,300 tonnes/annum (which equates to 120,000 cubic metreswith of bulk sediment volume), we believe TEMT needs to understand how much of this sediment washes through the Upper Reaches and downstream into the Rosevears/Nelson Shoals area, and how much and where the balance will settle in the Upper Reaches under various flows down the Cataract Gorge. The above BMT WBM report also shows that in 1984 the Home Reach/Yacht Basin area had about 643,350 cubic metres less sediment than required for stable equilibrium conditions. The report also states that the sediment accumulation will always drive towards this regime equilibrium condition providing supply is available. Given this claim, if the study shows that the volume of sediment in the Upper Reaches is continuing to build, how long will it be before the whole Upper Reaches section achieves regime equilibrium conditions and what will be the river conditions (width/depth) at that time? The Tracer Analysis Report of Sediment Redistribution carried out for the Launceston Flood Authority in May 2015 demonstrated the migration of sediment upstream into the Home Reach/Yacht Basin area under slow flow summer conditions so that it is logical that any study should look at total flows down the South Esk, including flows through the Tailrace, under summer and winter conditions, as well as with variable diverted flows down the Gorge. The photo below shows the size of Mud (Tamar) Island in 1834 and its greatly enlarged size in 2000. See more

19.01.2022 Sediment in the Upper Reaches A significant portion of the community believes that if natural flows are restored to the Cataract Gorge, or that if the flows through the tailrace were diverted via a 2.5km long canal back to an outlet opposite the Tamar Yacht Club, (the Greens Party policy) the problem of sediment accumulation in the Upper Reaches would be solved. When asked to address this issue of sedimentation in the Upper Reaches, the Tamar Estuary Management Taskforce (TEM...T) chaired by Allan Garcia, recommended that sediment deposition and transportation in the Yacht Basin be modelled under various flow conditions down the Cataract Gorge. While this would be handy data to have, with a mean supply of 120,000 cubic metres of bulk sediment volume entering the Tamar from the South Esk each year, the community would want to know how much of this sediment washes through the Upper Reaches and downstream into the Rosevears/Nelson Shoals area and beyond, and how much and where the balance will settle in the Upper Reaches between Freshwater Point and the Yacht Basin under various flow conditions down the Cataract Gorge. It is well understood that the raking program is only effective when carried out just before a serious flood event, otherwise it only temporarily displaces sediment downstream before the asymmetric tide brings it back up into Home Reach. See more

18.01.2022 Tamar Lake and flood mitigation When we have heavy rain in the Tamar catchment area that encompasses 15% of the surface area of Tasmania, the resultant flood waters travel down the North and South Esk rivers and their tributaries into the Tamar. In the current tidal environment the resultant flood level in Launceston is determined by three factors. 1. Obviously the amount and duration of rainfall in the catchment ... 2. The timing of when peak flows reach the Tamar from the two river systems. The worst case being when the peaks reach the Tamar at Home Point at the same time. 3. The timing of high tide in the Tamar and peak flows from each of the rivers. The very worst case is when all three events occur at roughly the same time. This was probably the case for the 1929 flood. We were fortunate in the 2016 floods in that the peak of the North Esk flows occurred well before the peak of the South Esk, and the tide was well below full when the South Esk peaked. In 2016, a event we all probably remember, the peak South Esk flows were 2398 cubic metres per second which is only 50% of what is classified as a 1 in 200 year event, and the peak North Esk flows was 1253 cubic metres per second which is 100% of a 1 in 200 year event. The Launceston levee system is designed for a 1 in 200 year flood event, assumably for worst case simultaneous tide and river flow events. In a Tamar Lake environment, the barrage at Point Rapid blocks an incoming tide and enables the level of the lake, with plenty of notice, to be lowered by at least a metre which provides a 45,000 megalitre buffer before flood waters fill the lake back to pre flood levels. The modelling carried out for Tamar Lake Inc. showed that flood levels in Launceston would be lowered by at least a metre for all flood events up to the 1 in 200 year event including provision for a sea level rise of 0.8 metres. With a barrage at Freshwater Point, the incoming tide will still be blocked, but the buffer will be considerably smaller. The modelling for this scenario has not yet been carried out.

16.01.2022 What about a mini Tamar Lake? With the announcement recently of the commencement of a feasibility study into the construction of a 4 lane traffic bridge across the Tamar, between Newnham and the West Tamar Highway north of Cormiston Road, as a major component of the West Tamar traffic flow improvements committed by the State government at the last election, Tamar Lake has had many enquires above the feasibility of co-locating a barrage with the bridge to form a freshwater lak...e in the Upper Reaches of the Tamar. A brief investigation has determined that provided there is an economic benefit in sharing the bridge foundations with the barrage and a ship lock, and providing the flood gates could be designed so that there is no detrimental effect on flood levels in Launceston, the principal technical goals of the Tamar Lake project, greatly reduced sediment accumulation in the Upper Reaches and protection against sea level rise in Launceston, will still be achieved. What benefits would this mean for Launceston and Tamar Valley residents and tourists? It would mean a clean, low pollution lake with a minimum 3 metre depth for all forms of aquatic sports 24/7, a greatly improved aesthetic presentation of the Tamar that will not only attract tourists but also increased commercial and residential developments that will contribute significantly to economic growth in the North. It will also be a major value add to a relocated university campus and other built infrastructure projects proposed for construction overlooking the lake.

14.01.2022 Cataract Gorge flows and Trevallyn Power Station. Cataract Gorge Flows I am totally in support of Alan Birchmore, as I am sure does most of the community, in wishing to see greatly increased permanent flows down the Cataract Gorge to restore the aesthetic presentation both for residents and tourists. A permanent flow of 20 cumecs would be sufficient. The maximum flow down the penstock from Lake Trevallyn to the power station is 90 cumecs; however, from data provided by Hydro ...Continue reading

14.01.2022 Introducing the Small Tamar Lake With high volume freshwater flowing down the South and North Esk rivers from a catchment covering 20% of the area of Tasmania, depending on the freshwater flows entering the Tamar, the river upstream of Freshwater Point is principally freshwater with a low salt content. A barrage installed near Freshwater Point (Legana) will separate the Tamar River into a fast-flowing freshwater reservoir approximately 15 kms long and a saltwater tidal estuar...Continue reading

14.01.2022 Sediment Management Studies on sediment management in the Upper Tamar have confirmed that the average rate of new sediment entering the Tamar from the catchment is 39,000 cubic metres per annum. The levee banks and our recreation are being compromised. The Launceston City Council has acknowledged that raking is not effective and that increasing flows down the Cataract Gorge has little effect on sediment accumulations in the Yacht Basin and Home Reach. The conclusion seems to ...be that the community will just have to accept the muddy low tide as is. I wonder what percentage of the community agree. Tamar Lake Inc., a member funded organisation, produced a Feasibility Study into all aspects of the installation of a barrage (a special type of weir with a ship lock facility) in the Tamar to form a freshwater lake separated from the tidal estuary. One finding is that with the removal of the asymmetric tide and the flocculation zone from the Upper Reaches, the lake will become a net exporter of sediment to downstream the barrage and the barrage will form an effective solution to the threat of sea level rise in Launceston. A 2nd possible location of this barrage is near Freshwater Point which would form a constant level freshwater lake from Legana to Launceston with reducing sediment volumes and a solution to the current navigation limitations. Perhaps spend the money saved on raking and potentially dredging to explore the feasibility of this permanent solution? Ask the State Government for assistance? See more

12.01.2022 Think about the last time you were down at the Seaport Wouldn't it be nice if while you were sipping on that nice, cold beverage, you saw nothing but crystal clear waters in your horizon? The Tamar Lake project will benefit the overall quality of life of those living in Launceston and the Tamar Valley, and will positively impact tourism and local business as well.

12.01.2022 Tamar Sedimentation - what alternatives do we have? With 152,000 cubic metres per annum of sediment entering the Tamar from the South Esk and North Esk catchmen...ts, and with the Launceston City Council acknowledging that heavier flows down the Gorge and raking programs are not effective, the Local and State Governments really only have three choices for the aesthetic presentation of the Upper Reaches of the Tamar. 1. Continue to allow that sediment to accumulate until some level of equilibrium is reached that is far higher than the current level and totally unacceptable to the broader community. 2. Conduct a continuous dredging program with the sediment spoils carried out by barge into Bass Strait. The continuous expense of this option would be prohibitive. 3. Change the hydrodynamics of the river with a barrage separating the freshwater flows from the catchment from the saltwater tidal estuary. The very extensive scientific and hydrodynamic modelling studies carried out and paid for by the 50 prominent members of Tamar Lake Inc. over the last 10 years, have shown clearly that there would be a net export of sediment from the Upper Reaches over time; the barrage provides an effective barrier to sea level rise flooding the low lying areas of Invermay; and the huge economic benefits of a clear, clean freshwater lake more than justifies the capital investment of barrage installation. The members of Tamar Lake Inc. are not asking the community to accept these results at face value, but for the State Government to set up an overarching Authority to be responsible for the health and amenity of the Tamar Estuary and work with other stakeholders to implement the programs necessary to make it the aquatic playground the community expects. See the sedimentation sections in the Feasibility Report available on tamarlake.com.au and you will see that the TEMT review of Tamar Lake is full of errors. One important issue is that the reviewer assumed that freshwater is released randomly from the lake which of course would promote flocculation downstream the barrage, when the modelling was carried out assuming releases only on an ebb tide with the result that sediment in suspension is carried out to Bass Strait.

07.01.2022 We pride ourselves on the Tamar Estuary as a major asset for Launceston. This photo was taken this morning just in front of one of our best restaurants, Stillwater. Who is responsible for maintaining this major asset?

07.01.2022 Tamar Lake - Case studies The Tamar Lake project proposes the installation of a barrage in the Tamar River to separate the incoming freshwater from the South and North Esk catchments from the tidal flows from Bass Strait. What is a barrage and why is it different to a dam?...Continue reading

07.01.2022 Tamar Management Every community survey nominates the Tamar River as a major natural asset for Launceston but what single organisation is responsible for the maintenance of this natural asset? At low tide it is an unsightly mess with shopping carts and bicycles stuck in the mud; the collapsed North Esk retaining wall; the remains of the old Kings Wharf; the skeletons of sunken boats and muddy stinking water. If it is the Launceston Council, what is it going to do about contin...ued sediment accumulation at the rate of 120,000 cubic metres per annum in the Yacht Basin and Home Reach? The current navigation depth in the Yacht Basin is as low as I have ever seen it with the small tourist boat unable to enter the Gorge at low tide. Now that the Council has acknowledged that raking is not effective and that increasing flows down the Gorge has little effect on sediment depth in the Yacht Basin, their party line appears to be that this is the natural state of the estuary and that the Launceston community is just going to have to accept this continued loss of aesthetic presentation and aquatic amenity as the sediment volume in the Upper Reaches continues to build. Yes, they have hinted at a continuous dredging program to maintain a navigation channel as they did when the Port was in Launceston and they had the Port revenue to pay for it, but what about the ongoing cost; where will the dredging spoils go and what effect will this have on water quality? For years, the Launceston Flood Authority justified the raking program on flood level minimisation. Has the Council lost sight of this danger as every centimetre build up of mud increases the flood level by a centimetre. What about the protection of the low lying areas of Launceston against sea level rise? The current levee system may protect against infrequent flood events, but it won’t protect against twice per day sea level rise full tides. Why doesn’t the Council invest the money it is saving on raking, and potentially on dredging, into investigating the feasibility of installing a barrage and ship lock in the Legana/Freshwater Point area to form an Upper Reaches freshwater lake. This not only greatly enhances the aesthetic and aquatic amenity of the Yacht Basin/Home Reach/Lower North Esk area, but permanently reduces the rate of new sedimentation build up in this area and provides a solution to the Sea Level Rise threat to the low lying areas of Launceston. If the Council is not responsible for the river below high tide, what organisation is? Is it a State responsibility and if so, where is the Authority with the power and funding to take action? It is time to set up that Tamar Estuary Management Authority with over arching responsibility for the health and amenity of the Tamar River, as has been mooted for the last 10 years. Robin Frith