NOW’s Preliminary Report on the drying up of World Heritage Thirlmere Lakes


Rivers SOS is disappointed in the report from NSW Office of Water. Their findings are summarised in the attached media release, which also gives the link to the 80-page report itself.

We feel there has been a too-hasty attempt to publish something, however inadequate, to adress the concerns of so many locals and others who love these lakes, which are/were the most beautiful part of the World Heritage listed Blue Mountains National Park ,but have been drying up for the past few years.

Though this is entitled a “preliminary” report we suspect that there is an intention to bury the troublesome issue before the March election – we doubt that a full report will be completed before then, meanwhile this document absolves longwall mining from any blame. Once again the drought is blamed.

However in this Warragamba Catchment the drought was broken over two years ago, in 2008. Rivers SOS waited through a year of heavy rain before we felt we could conclude that longwall mining may be a cause of the drying up of the lakes.

In past droughts records show that the lakes refilled rapidly after rain, but this has not happened. Local people who frequent the lakes remark that they have been slowly drying out since longwall mines went 700m away, while 4 megalitres of water per day are pumped out from the mines, no doubt depleting the ground water which has fed the lakes for 15 million years.

Moreover independent mining experts hold similar opinions to ours – see comments from Professor Philip Pells below.

Professor Pells is happy for the media to publish his comments and his phone number is 43847055.

Previously we sent you a short analysis of how mining may have fractured the aquifers, from a paper given by retired professor Dr Brian Marshall. He was also happy for this to be published. His phone number is 47841148, m: 0403804994.

Both Pells and Marshall have long experience in mine subsidence and geology and hold or have held senior academic positions.

Water Minister Phil Costa promised Rivers SOS members in December that he would get together a round table of experts from his department plus interested experts from outside, such as Pells and Marshall, to discuss the disappearing Thirlmere Lakes. We would appreciate it if the media could ask the Minister when this might take place.

Professor Pells’ comments are as follows, in response to a request from Caroline Graham of Rivers SOS:-


I am on holiday till the 11th so have had to read the 80 page report “Thirlmere Lakes Groundwater Study” on my iPhone- no mean feat!

The report has a lot of generalized geological and hydrogeological data that is of little relevance to the Thirlmere Lakes. However, it does contain some interesting data from the Dpts groundwater monitoring bores(regional) and from Xstrata’s monitoring bores. These will warrant careful study.

What I can say at present is :

1 the assessment of the geological regime beneath the lakes is poor. There is no interpreted profile down to seam level, no mention of the Bald Hill Claystone, and no analysis of the Holocene sediments beneath the lakes.
2. The analyses of groundwater changes associated with the longwalls is so simplistic as to be incorrect.
3. The analyses of rainfall records is simplistic in that there is no quantification of the post-2000 drought relative to earlier droughts for which there is some information as to lake behavior.
4. The data from Xstrata’s monitoring bores is of questionable relevance given that they are all well to the NE and E of the longwalls that could have impacted on the lakes
5. No effort appears to have been made to collect and collate information as to historical lake levels.

Overall I can only conclude that the NSW Government has jumped the gun in tracing a conclusion as to the reasons why the lakes seem to have remained dry when the drought has well and truly broken. Just possibly, the conclusions of the report could be correct- but, I think that would be more a matter of luck than good science.

I will take some time to collect, collate and properly analyse all relevant hydrological, anecdotal, groundwater, geological, monitoring, and mining data. Only then will it be possible to reach robust scientific conclusions,

You may quote me, as you wish.


Philip Pells

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2 Responses to NOW’s Preliminary Report on the drying up of World Heritage Thirlmere Lakes

  1. Shirley says:

    I went to tons of links bfoere this, what was I thinking?

  2. Ceciley Anne Furtner says:

    I was very saddened & in shock to see this once beautiful lake now dried up….with no real explanation as to “why” after 15 million years, after rain, as it did for years & years, refill the beautiful Thirlmere Lakes!!!? Longwall mining????

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