Dr David Leaman’s Midlands Water Scheme report has started dialogue with Hydro Tasmania. Here we let both parties have their point of view.
From a letter from Gregory Carson, Water Operations Team Leader, Hydro Tasmania:
The report contains a significant error which means that some of the conclusions reached are misleading. On pages 5-6 the following statements are made:
The long term flow pattern at Llewellyn … is comparable to that at Perth … for the period where the two records overlap.
In the period which enables comparison (from December 1972) it is evident that little water was gained between the two stations implying that the flow from the Nile, Lake Macquarie and Liffey systems is either very small or almost wholly committed to towns, agriculture, irrigation, ground water recharge and evaporation.
Note that the Perth gauge should also receive benefit from Poatina releases.
It would appear that Dr Leaman did not check a map prior to writing the above. If he had check a map he would have realised that none of the water from the Liffey River, the Lake River, or the releases from the Poatina power station flow via the Perth gauging station.
These errors influence a number of the statements relating to water availability at Trevallyn dam and power station. For example, there is no shortage of water at Trevallyn dam for meeting environmental flows and town water supplies as appears to be suggested on page 8 of the report. In 2008, 922 giglitres was discharged from Trevallyn power station. This greater than the volume of water used for all purposes in South Australia.
Given the errors I suggest that the report is removed from your website to give Dr Leaman an opportunity to address them.
Dr David Leaman’s reply:
Mr Carson of Hydro Tasmania recently wrote to you asserting that this report is in error, should be ignored and removed from your website (the real goal, remove the criticism from public view).
I do not resile from the content of that report, and the thrust and conclusions are not affected by ‘the mistake’. Even so, I have enclosed a revised version to clarify the matter and my intent as explained below.
Hydro/TIDB will like it less than the orginal …
I am always fascinated by reaction by Tas Govt agencies to criticism of any sort. I am grateful to Mr Carson, this case, for his quite exceptional courtesy in providing a copy of his comments (or I would not have known of this attempt at silencing).
Greg Carson comments on one small section of one report (in a set of three in several parts) in which I accept there is one small editorial ‘mistake’ — it is true that the Perth gauge does not monitor Poatina releases. This is a complete and irrelevant nitpick. Note that no other statement has been faulted.
The normal catchment of Lake Macquarie and Nile River do flow to the South Esk. Nor does he comment or note that the entire context relates to Trevallyn (see page 3) and its storage — fed by Liffey, Meander, Poatina diversions as well as the direct South Esk.
Note that the South Esk catchment includes Trevallyn and The Gorge as well as the power station.
The so-called error does not affect any conclusion with respect to Trevallyn.
His comments on 2008 water releases are interesting. I am sure many in Launceston would love to know how generous these were and then hear why there were shortages and restrictions, and why the pathetic environmental flow levels legally maintained in the gorge can be justified as adequate.
This kind of discussion is needed if we are not to enact silly policies.
Download the original report: Midlands Water Scheme [PDF 374Kb].
Download the updated report: Midlands Water Scheme (revised)r [PDF 387Kb]
Comments are welcome. The Editor.
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