11 August 2008

The Cotter Dam Enlargement - where will the Dam Wall stop, and what about the picnic area?

| Peter Holland
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I was watching the telly last night, and the ad for ACTEWAGL came on, talking about the need to increase the dam size. It takes a while to sink in with me, and I have watched this ad several times, but it only just made it through the “switch off – its an ad…”

Where will the dam wall end?

Will the picnic area remain, or will it be buried under the wall?

Important stuff – best place to go in summer, seems to remain fairly cool in summer at that spot, and I would hate to lose it to a dam.

As would my daughter – she has only just found the playground….

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peterh said :

whoops, came across this on the actew website….

http://www.actew.com.au/water2water/EnlargeCotterDam.aspx

explains as to how the cotter dam enlargement will be filled.

here is an excerpt:

“While a larger Cotter Dam will provide additional storage capacity, if water inflows to the ACT’s catchments continue at record low levels (down by almost 65 percent on average over the last six years, and 90 percent in 2006), there will be insufficient water to fill the dam.

Hence the need to consider topping up the Cotter reservoir with purified water in parallel with the Cotter Dam enlargement. These two projects combined would further enhance the security of the ACT’s water supply into the future.”

Mr Evil is right!

aaaah!

I wonder how that fits in with the Murrumbidgee Catchment Management plan, and specifically how much water Canberra can take out of the catchment/has to put back in? Our treated waste water currently flows straight back into the ‘Bidgee, so I’m betting that treated water is somehow not counted as part of the catchment, which would be a loophole that would allow the ACT to treat and recycle its water. Why is this important? Because it is unlikely that the ACT will ever be able to negotiate a bigger slice of the catchment’s supply given the myriad problems downstream.

As for those afraid of recycled water, or overwhelmed by the ‘yuck!’ factor, get over it. The technology is safe, proven, and used all over the world. I like peterh’s attitude: ““water” is loosely termed “anything that runs faster than dirt”, won’t be a problem for me.” lol

Mr Evil said :

miz said :

‘bluegreen algae would be a dead giveaway…’ and let’s not forget typhoid, giardia, crypto etc. Yum. Not. I really would prefer dammed rain water to poo water. Hurry up with that dam, and stop wasting money on a ‘demo’ sewage processor (and those annoying ads).

Next time you are having a nice big glass of fresh, clear, clean Canberra water, try to imagine all the dead roos, wombats, birds, missing trampers, rusty car wrecks, polution, run-off from septic tanks and agricultural chemicals that end up in the Googong, Corin, Bendora and Cotter.

ah, yes.

but as i am from adelaide, where “water” is loosely termed “anything that runs faster than dirt”, won’t be a problem for me.

miz said :

‘bluegreen algae would be a dead giveaway…’ and let’s not forget typhoid, giardia, crypto etc. Yum. Not. I really would prefer dammed rain water to poo water. Hurry up with that dam, and stop wasting money on a ‘demo’ sewage processor (and those annoying ads).

Next time you are having a nice big glass of fresh, clear, clean Canberra water, try to imagine all the dead roos, wombats, birds, missing trampers, rusty car wrecks, polution, run-off from septic tanks and agricultural chemicals that end up in the Googong, Corin, Bendora and Cotter.

thumper, I was having a jape re the sensitivities about “recycled” water. half the time, with bush blocks, your water is brown. if you make a pot of tea, it is still brown. add milk, light brown.

read the book “the great boomerang”. now there was a pretty far-fetched idea, but one that just might make sense in the future…

miz said :

‘bluegreen algae would be a dead giveaway…’ and let’s not forget typhoid, giardia, crypto etc. Yum. Not. I really would prefer dammed rain water to poo water. Hurry up with that dam, and stop wasting money on a ‘demo’ sewage processor (and those annoying ads).

ah, but you missed the excerpt. The water would be a mix of both, as the catchment is no longer providing fill levels that are able to increase the levels of the dam significantly.

so…

poo water with rainwater, and who wants to see what the color will be, people complain about tannin anyway, what if it is believed to be from the mixing? brown stained water.

yum.

Mælinar - *spoiler alert* I've seen S04E138:13 am 13 Aug 08

@miz – I think among the RA crowd we can drop the charade of ‘demo’. We are all enlightened enough to recognise that as soon as this thing is operational we will be drinking recycled poo courtesy of JON STANHOPE.

If he wants this to be his Coda – I think it only fair that we recognise it for what it is and name it the Jon Stanhope Memorial ‘demo’ sewage processing water treatment facility.

@Everybody – On that thought though, wouldn’t it simply be easier if we all went up to the Cotter enlargement and did our business in the dam ? You know it makes sense. They want it filled, and the water is going to get treated anyway.

Timberwolf652:12 am 13 Aug 08

I remember as a kid, taking the exciting walk up to the top of the dam, There was a statue type thing across the river that reminded me of a dalek from dr who, the old wooden suspension bridge… I miss it all, why must things change!!!!

‘bluegreen algae would be a dead giveaway…’ and let’s not forget typhoid, giardia, crypto etc. Yum. Not. I really would prefer dammed rain water to poo water. Hurry up with that dam, and stop wasting money on a ‘demo’ sewage processor (and those annoying ads).

mooliganbags18:19 pm 12 Aug 08

Can anyone remember talk of a desalination plant which pumped water over the mountains into Canberra last year or did I just imagine it?

GottaLoveCanberra7:36 pm 12 Aug 08

Is an environmental impact study being done on this project?

Wouldn’t want to disturb the bearded green-eyed yellow bellied four winged amazonian blinking spotted dog bird lizard now would we?

VYBerlinaV8_the_one_they_all_copy4:10 pm 12 Aug 08

Peak rain months in Canberra are around November, I think, so after our wet(ish) winter it will be interesting to see if we get much in the way of rain later this year.

ok, native wildlife floating with their legs in the air, then…

iCanberran said :

From what I’ve read, the water in the Googong catchment, rich in farm chemicals and manure is (hopefully) far worse than anything we would be flushing into a recycling plant.

of course, if the purifying treatment went wrong, we would soon know about it. bluegreen algae would be a dead giveaway…

From what I’ve read, the water in the Googong catchment, rich in farm chemicals and manure is (hopefully) far worse than anything we would be flushing into a recycling plant.

whoops, came across this on the actew website….

http://www.actew.com.au/water2water/EnlargeCotterDam.aspx

explains as to how the cotter dam enlargement will be filled.

here is an excerpt:

“While a larger Cotter Dam will provide additional storage capacity, if water inflows to the ACT’s catchments continue at record low levels (down by almost 65 percent on average over the last six years, and 90 percent in 2006), there will be insufficient water to fill the dam.

Hence the need to consider topping up the Cotter reservoir with purified water in parallel with the Cotter Dam enlargement. These two projects combined would further enhance the security of the ACT’s water supply into the future.”

Mr Evil is right!

aaaah!

miz said :

Except dustbowls, unlike trees, do not help with carbon. To quote Michael Pollan (article in Sept issue of Gardening Australia, p 51),

‘the single greatest lesson a garden teaches is that our relationship to the planet need not be zero-sum, and that as long as the sun still shines and people still can plan and plant, think and do, we can, if we bother to try, find ways to provide for ourselves without diminishing the world.’

okay, lets drain the lakes, give every household a tank, fill it with lake water (who would be insane enough to drink THAT water?), and get more trees into suburbia. Not natives, but in canberra, what trees produce higher levels of oxygen, yet can withstand the cold weather?

if we can create a cold bowl here, instead of a heat sink, which is what each lake does to the environment, we would see the rains more often.

Lakes trap heat. clean them out, use the water for something other than the arboretum, and plant more trees. where’s that political slogan?

Perhaps they plan to fill the new dam with recycled sewage water?

It’s a conspiracy – I tell you!

Except dustbowls, unlike trees, do not help with carbon. To quote Michael Pollan (article in Sept issue of Gardening Australia, p 51),

‘the single greatest lesson a garden teaches is that our relationship to the planet need not be zero-sum, and that as long as the sun still shines and people still can plan and plant, think and do, we can, if we bother to try, find ways to provide for ourselves without diminishing the world.’

sexynotsmart9:30 am 12 Aug 08

RuffnReady said :

Assuming that this new dam will alleviate the need for continued water restrictions is naive…

My fear is ACT will be on perpetually stage 4 or 5 restrictions. They are really, really hard! I have no issue if the “powers that be” determine Stage 2 or 3 restrictions should continue indefinitely. And if the estimates referenced by everyone’s friend Professor Garnaut are correct, we’ll be on Stage 2 or 3 for many years to come.

RuffnReady said :

The dam is about increasing the capacity of the Canberra water supply system to account for a larger city and longer droughts – whether that capacity is utilised (ie. the water falls from the sky) is another matter…

Spot on! But we’d be a mob of twonks to expect the water situation will just magically fix itself. IMHO the more perilous path is to do nothing. There’s a better chance of storing more water for drought with the ACTEWAGL changes than without. And remember the bigger dam is only one of the proposed projects.

And finally…

miz said :

I hope they don’t have to move the playground. Those shady trees that make it so pleasant took years to grow. I would have thought there was a heritage element.

To paraphrase yet-to-be-born James T. Kirk (who will probably spin in his still-to-be-filled grave), but “The needs of the many outweigh the needs of the few”. Most of urban Canberra would turn to a dustbowl on extended Stage 4 or 5 restrictions. I think that involves a large heritage element too.

I hope they don’t have to move the playground. Those shady trees that make it so pleasant took years to grow. I would have thought there was a heritage element.

Actually its three new dams. Main dam and two saddle dams.

http://img504.imageshack.us/img504/5672/newcotterdamey3.jpg

RuffnReady said :

Assuming that this new dam will alleviate the need for continued water restrictions is naive – an extended dam doesn’t change the quantity of rain that falls! Notice that even though we are in a La Nina and experiencing a relatively wet winter, the quantity of water in our dams has not increased significantly. That is a mismatch between consumption and rainfall (and catchment agreements made to allow water to pass downstream into the Murray system), not a dam capacity issue.

The dam is about increasing the capacity of the Canberra water supply system to account for a larger city and longer droughts – whether that capacity is utilised (ie. the water falls from the sky) is another matter. In the new weather paradigm, cities need storage for more than 3 years of drought, we’d just better hope that enough rain falls to fill that dam capacity… or be more rational about our consumption of water in a dry region and use less.

Well said, last I saw the dams were still well under 50% full. Winter is almost over, unless the spring is extra wet it’s not a good start to the warm seasons. You can build the dams as big as you like, but if they don’t get filled up, you may as well not bother.

Mælinar - *spoiler alert* I've seen S04E137:55 am 12 Aug 08

So they are replacing the playground with a pool. Whoop-de-do.

Assuming that this new dam will alleviate the need for continued water restrictions is naive – an extended dam doesn’t change the quantity of rain that falls! Notice that even though we are in a La Nina and experiencing a relatively wet winter, the quantity of water in our dams has not increased significantly. That is a mismatch between consumption and rainfall (and catchment agreements made to allow water to pass downstream into the Murray system), not a dam capacity issue.

The dam is about increasing the capacity of the Canberra water supply system to account for a larger city and longer droughts – whether that capacity is utilised (ie. the water falls from the sky) is another matter. In the new weather paradigm, cities need storage for more than 3 years of drought, we’d just better hope that enough rain falls to fill that dam capacity… or be more rational about our consumption of water in a dry region and use less.

Agreed with #8,9 and 10. A playground can be moved, and the construction and trucks will eventually go. I think storing more water for an ever increasing population is more important.

sexynotsmart7:52 pm 11 Aug 08

I totally love the Cotter picnic area too! But I don’t mind it being inaccessible for a couple of summers if the end result is more stored water.

I mean perpetual Stage 4 or 5 restrictions versus using Pine Island or Tidbindilla for a while… it’s a no-brainer for mine.

Sadly, the existing dam will be completely submerged by the new dam, to be located further down stream. The TV commercial shows the original dam wall to the left of a CGI animation of a new dam, followed by an animation of water submerging the existing dam.

You can get all the info here: http://www.actew.com.au/WaterSecurity/MajorProjects/enlarging_cotter_dam.aspx

I’ve wondered about this and tried to look it up. I can’t tell either way, but it is clear that the water body is pretty close to the recreational area.

What worries me most is that ACTEW hasn’t definitively said that they will preserve the recreational area. I heard something on the news a couple of months ago which seemed to imply that there was ambiguity over the situation – it was deliberately dodgy wording by some ACTEW spokesman.

ACTEW seem to be the new B*stards incorporated arm of the ACT Government. Notice how the TV ads are attempting to repair their damaged reputation in the wake of the power station fiasco.

Yes, but think about how are they going to build this dam extension? The wall itself may not extend into the picnic/recreation area, but the construction process will have to. Trucks, heavy machinery, earth-moving equipment, all using our favourite scenic Cotter Rd day in day out for the duration of the build. This alone will take its toll on that tired old road. Access to the site for something of this magnitude will surely be making use of the recreation area. Certainly I’m in favour of forward planning and the development of Cotter Dam for the future, its a significant asset for the region and should be maximised, but it will be at a loss to the Cotter as we know it today.

There ya go – so its really a dam enlargement – the impression that the advertisement gives is that they were going to reinforce and extend the existing dam wall…. Wouldn’t it be cool to walk across the new dam on the old dam wall and appear to be walking on water 🙂

Actually, last I checked, the plan was to build a whole new wall (extending an existing one not designed for the increased capacity would be more trouble than it’s worth) just a little bit downstream (thus simply flooding over the top of the existing wall). If you’re asking about the picnic area next to where the pub used to be, as far as I know that’s going to be untouched by the dam itself (though they’re talking about taking the opportunity “to coincide the dam construction activities with remediation to the Cotter precinct”, whatever that may mean).

No, a whole new dam is being constructed some distance in front of the existing 1915 dam.

I’m guessing it will have no impact on the Cotter picnic area, but I’m sure if it did, then Labor would be very open to public consultation on the issue. 😉

Which picnic area do you refer to ?
If you mean Cotter reserve, I guess that would be fine, because its downstream of the dam.
I am guessing that the dam wall will be extended in height allowing the capture of more water so its safe to say that depending on how much higher the dam wall goes, there will be x meters of vertical shoreline that will now be underwater…..

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