Looking at the big picture for Launceston and the Tamar Valley, I am encouraged by the cooperative activities of the various government funded bodies in the one common long term aim:Mountains Photo
The Launceston Flood Authority has just completed the development of the flood levee system around the low lying areas of Launceston to protect against a 200 year ARI flood event under current tidal and sea level rise scenarios.
Preliminary results of this program to develop an understanding of the sources and quantities of the sediment, nutrients and bacteria entering the Tamar from the catchment and the possible effects of remedial actions over time has been presented to Tamar Lake and stakeholder. This report will be made public in about the October time frame by NRM North, but it is clear that any remedial action will be at least a 10 to 20 year program, made more imperative by the projected growth in irrigated agriculture and urban expansion over the life of the plan.
We understand that the extensive funding required to manage the implementation of this plan has not yet been estimated.
TasWater has developed and obtained community agreement on the 50 year LSIP strategy that will ensure that all sewage and stormwater will be treated to the tertiary level prior to any release into the Tamar and its catchments.
We understand that tenders have been called for carrying out the feasibility studies necessary, but the funding commitments of the estimated $100 to 200m for planning and implementation has not yet been obtained.
With federal and state funding of $140,000 this model, which is being developed by the consultants BMT WBM and being managed by NRM North, was due to be completed by the end of June.
Unfortunately, due to the difficulty in obtaining some of the actual measurement data necessary for calibration of the model, the completion date and documentation of the model has been delayed until mid-August, which means that the results for the Tamar Lake scenarios will not be available until mid-September.
While this is disappointing, the delay of 2 ½ months is not critical in the scheme of the whole project, and it is important that the developed model be as accurate and robust as possible.
Assuming the results of the Tamar Lake 3D modelling studies are as expected in mid-September, this will mark the successful completion of the very extensive 4 year study program demonstrating the feasibility into the technical, environmental and economic aspects of the Tamar Lake project.
Projected cost for planning and construction of the barrage is $320m, with completion by 2022.
While the cooperation between the various authorities (LFA, TasWater and NRM North) and Tamar Lake Inc in the strategy formulation and feasibility phases of the above projects could not have been better, as the projects move into the detailed planning phases there are many technical, environmental and economic dependencies between projects that make implementation very difficult unless they are all brought under the one funding and management authority.
For example, from a water quality viewpoint, the Tamar Lake project requires the implementation of the WQIP and LSIP plans over a 10 year period, with each estimated to cost in the order of $100 to $200m.
However, with no tangible economic benefit to the region, funding of these programs may be difficult without the very large economic benefits to be gained by the implementation in parallel of the Tamar Lake project.
The question the State Government needs to ask is “is there a higher probability of obtaining infrastructure funding for an expenditure of $200 to $400m over 10 years without any tangible economic benefit, or $500 to $700m for an incremental increase of at least 2.3% in GSP over the same period, and the commensurate increase in construction and long term employment in agriculture, tourism and manufacturing industries.”
In considering the installation of a barrage in the Tamar River to solve the silt accumulation problem in the upper reaches, and provide the foundations for a major boost to economic activity in Launceston and the Tamar Valley, it is important that we examine and learn from the history of other estuarine barrage systems around the world, and the effects on the environment and economic developments of the towns and cities through which the river system flows.
In the initial studies carried out by Tamar Lake Inc, we identified two barrage systems in other countries that, while having some effect on the environment, in balance stimulated a huge economic boost to commercial and tourist development of the area surrounding the lake formed behind the barrage.
These two examples were covered in detail in the document “The Tamar Valley, a Vision and Strategic Plan, Part 2, available from our website at www.tamarlake.com.au
In both cases, the commercial development around the shores of the lakes has been extraordinary, and they have both become major tourist attractions in their own right, but both projects have also involved parallel development of measures to manage flooding of the banks of the lakes, and to maximise water quality through the minimisation of pollutants from diffuse and point sources of sediments, nutrients and bacteria flowing into the lake from the catchments and urban runoff.
If any further convincing that a clean/green silt free Tamar is achievable was needed, a 6 night river cruise on a 75 cabin/150 passenger cruise liner from the centre of Paris to the Seine estuary entrance at Honfleur, has confirmed my views.
With climate and rainfall conditions very similar to Northern Tasmania, and average river flows about the same as the South Esk, today the 760km long Seine presents as a clean, wide, deep (9 to 10 metres) highly trafficked waterway the 370 km from the Eifel Tower to the English Channel. It is the source of drinking and industrial freshwater for the developed areas of Paris and other cities and towns on the river, and agricultural irrigation for the extensive farmlands in the greater Seine Basin.
However, this has not always been the case. It was only 40 years ago that the Seine River was declared “dead”. Levels of pollution from industry and agriculture were dangerously high; native fish had disappeared; plant life was dying and the water was unsafe for swimming. (Is this familiar?).
Today, the city of Paris organises fishing contests and swimming races in the Seine on summer afternoons.
Burdened and supported by a population of 17 million in the Seine Normandy Basin, an extensive development of point source sewage treatment infrastructure and an on-going program of farm management practice improvement has cleaned up the Seine.
From a navigation and freshwater supply viewpoint, the river has been segmented into a tidal estuary that allows ocean going container and bulk freight ships to load and discharge their cargoes at the port of Rouen, 120 kms upstream from the mouth; and a series of 6 freshwater lakes with a total of 7 barrage/lock combinations between Rouen and Paris that not only provides a secure supply of freshwater for domestic and agricultural applications, but also a constant navigation channel depth for freight barges and river cruise liners all the way to Paris.
Much of the credit for the improvement in the health and amenity of the river has been given to the administrative decision in 1964 to form six river management authorities to be responsible for each of the six natural hydrographic lake units formed by the barrages. The average size of each lake unit is 40kms, about the same length as Tamar Lake.
Before the installation of the first barrage in the late 1800s, the river in Paris consisted of a small, shallow channel of continuous flow, bordered by sandy banks. Today, despite the low average flow, the depth of the lake is tightly controlled at 9.5 metres, and the entire width of the river between the built-up banks is normally filled with water.
The water level in Paris is 24 metres above sea level, with each of the seven barrages dropping the lake levels by 3 to 4 metres. The same maximum drop as the single barrage forming the proposed Tamar Lake.
From a tourist viewpoint, the entire waterway is a clean, low turbidity passage with no sign of silt accumulation on the sand and gravel banks until the estuary mouth, where the very large tide of 7 to 10 metres with storm surges even higher is posing a problem for the authorities with huge volumes of coarse sand forcing its way a short distance up the estuary and tending to block the passageway into the English Channel.
This is unlikely to be a problem at the entrance to the Tamar, but our 3D modelling will resolve this question.