The comment by CP on my 2007 article –There never was a rain shortage to justify seawater desalination for Perth’s water supply – has prompted me to post the May 2012 reply from WA Minister The Hon Bill Marmion.
First – here are some relevant links – 2002 article in The West Australian Water bosses snubbed plan
This page has a graphic showing the effect of thinning – third graphic down.
“Effects of catchment thinning at Higgins near Dwellingup from WC online report”
Reply from the WA Govt Water Corporation to an article in the Rockingham local paper June 2005 The Sound Telegraph – thats Cockburn Sound.
On 14 March 2012 I emailed the WA Minister –
Dear The Honourable Bill Marmion,
You should know that Perth dam catchments are blessed with rainfall averaging over 900mm per year – and that is just in the May to October runnoff season.
Yet by decades of not managing catchment vegetation efficiently your water supply authorities are progressively decommissioning your network of dams – great facilities mostly put in place by the sweat, foresight and prudence of earlier generations.
This graphic demonstrates the relentless loss in catchment efficiency.
I have more online with my article “2011 update 37 year Perth dams catchment rainfall trend – nearly a Thousand GL of water wasted over 15 years by not managing catchments”
Please make sure you checkout my 3 page word doc linked at my online article;
“There never was a rain shortage to justify seawater desalination for Perth’s water supply”
December 4th, 2007
To improve the resilience of the Perth water supply using the most environmentally friendly and low cost methods – here is what you could do Minister.
[1] Order that dam catchment vegetation be managed so as to aim for a catchment efficiency figure of near 6%.
[2] Order that the Gnangara pines be cut forthwith in favour of native bush – the pines value as saw logs is probably less than the value of the Gnangara Mound water that they are wasting, taking water values as per the average of your desalination plants.
I would suggest that after those measures take full effect – dam levels should recover to where you might be able to close down some of your very expensive seawater desalination capacity. That would save many millions of taxpayer dollars.
You should also be able to postpone the expensive venture to tap deeper groundwater. More savings.
Please let me know if you have any questions Minister.
Yours sincerely,
Here is the reply from Minister Marmion.
Dear Mr Hughes
Thank you for your email dated 14 March 2012 regarding the management of
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I recognise that vegetation has been contributing to a reduction of inflow into surface water reservoirs of Perth’s forested surface water catchments.
A trend in reducing rainfall since the 1970s is also a considerable factor in this reduced catchment recharge . The assertion that rainfall to our dam catchments is over 900mm per year is generally true . However, this rainfall is declining markedly through the south west and is below 900mm in the significant Mundaring Weir catchment.
It should also be noted that rainfall reduction and streamflow to dams is not a linear relationship.
Once groundwater disconnects from the streams there is a significantly greater reduction in streamflow.
A recent study by the CSIRO (currently in review , pending publication) has found that the denser vegetation in Perth ‘s forested catchments is responsible for approximately one-third of the run off decline to our reservoirs. The remainder is mainly attributable to rainfall decline.
The Department of Water (DoW) has been researching this issue for some time and has also been working with other agencies and researchers on options to address
vegetation management issues . A prime example is the DoW and Water Corporation’s Wungong Catchment Thinning Trial, which is investigating the impacts of increased forest thinning on improving surface water catchment recharge in Perth’s forested water catchments.
The DoW has also contributed to the development of the Department of Environment
and Conservation ‘s (DEC) next Forest Management Plan regarding the issue of forest vegetation management and its impact on forested surface water catchments. I understand the draft plan is expected to be available for public comment by late 2012.
The DoW is also coordinating a scientific review of the rehabilitation option for mine bauxite rehabilitation in the northern jarrah forest to inform future practice.
You may also be interested in the following CSIRO report which provides information on current and future water yields of both aquifers and surface’water catchments,
www.csiro.au/Organisation-Structure/Flagships/Water-for-a-Healthy-Country-Flagship/Sustainable-Yields-Projects/SWSY.aspx.
I appreciate your interest and demonstrated concern for the future of Perth’s water supply.
Yours sincerely
HON BILL MARMION MLA
MINISTER FOR ENVIRONMENT; WATER
11 May 2012
You are right to pursue this issue. The whole thing smells of a deliberately manipulated situation to keep the climate crisis grants rolling and absolve Water Corporation management of responsibility.
Meanwhile the Water Corporation is ‘upgrading its website, removing some very useful pages on rainfall and dam levels with flashy, totally useless graphics.
On the new stream flow page they say,
We need steady, regular rain in order to soak our catchments and get the streams flowing into our dams.
Which is the opposite of the truth. The more irregular the rainfall the greater the runoff precisely because it gets less chance to soak into the ground where plants/trees can access and transpire it.
Climate Chaos meme peddling.
So the Honorable Bill Marmion receives his CSIRO report (now they have never gotten anything wrong before have they?) and says “well there we are, my job is done. Somebody pass me my rubber stamp”. Thanks for your diligence Bill
Minister Marmion admits you are correct:
The estimate that most of the runoff decline is from reduced rainfall may or may not be correct, but is quite irrelevant to policy. There is nothing to be done about the weather – although cloud seeding would probably work if they tried it again.
Similarly the scientific bromides about non-linear relationships and disconnection of streams from groundwater are all very well but beside the point. The point is, how full would the dams have been if they had let water run into them instead of growing pine forests with it? Would WA still have needed to blow billions on desal? Did the CSIRO boffins even bother to work this out?
I suppose once the Thinning Trial is concluded and another few reports written, the all-knowing Department will chop down at least some of the pine forests and other vegetation soaking up the water, and who knows they may even save a few shekels buying less ghastly desal water. But they are acting as if this was all perfectly normal, when the fact is they have made a right royal stuffup of managing the water supply of 2 million people, causing artificial shortages and huge cost blowouts. And the message they have given the public is that this was due to global warming! Words fail me – and if I found them, you would have to cross them out Warwick.
Perth Water Corp has updated their website to a totally user un-friendly site:
watercorporation.com.au/water-supply-and-services/rainfall-and-dams
I noticed that they have now snuck in water run-off into dams as a graph; anyone checked this?
The link tells us –
Rainfall, dam storage & water supply
We hear you
Changes to this section are underway, please be patient as we work on this.
Here you can check rainfall and dam levels and find out how declining rainfall is affecting the amount of water that flows into our dams.
You can also learn where we source your water from and how our water usage is tracking.
WaterCorp used to have an graphic like so which was updated often. Have to say since leaving Perth in 2008 I have not kept up to date with what WaterCorp does.
My old Perth Water Users site has lots of info and graphics of how WaterCorp portrayed dam levels in years now gone by.