HUNDREDS of millions of dollars have been spent on fishways, resnagging, riparian revegetation, not to mention the billions for water buyback, all recommendations of the Native Fish Strategy for the Murray Darling Basin 2003-2013 [1]. Those who implemented the program, however, claim no progress, in particular that numbers of Murray cod are still in decline [2]. 
Interestingly there has been no review of the program of works over the last ten years against the original recommendations in the strategy. Yet such a review could throw light on why, despite all the money spent, Murray cod numbers are still apparently in decline.
Many fish experts met many times to make recommendations that underpinned the strategy. A key recommendation, repeated in the planning documents and then the final strategy, was that the issue of cold- water pollution from the dams needed to be addressed. Indeed the expert panel that oversaw development of the Strategy were confident that the abatement of cold water pollution was the most tangible and achievable of all the proposed interventions to the extent that this “threat could be largely removed from the Basin within 10 years”.
In reality nothing, absolutely nothing, has been done to address it.
The Hume and Burrinjuck dams, like most of the dams through the Murray Darling, have the outlets for irrigation positioned at depth creating a jet of cold water.
Government commissioned reports have considered different techniques for cold-water abatement including retrofitting with multi-level outlets, artificial destratification through mechanical mixing, trunnions (pipes hinged at the outlet drawing water from different levels), surface pumps (large fan-like propellers that pump warm surface water into existing outlets), and submerged rubber curtains to stop the flow of cold water to the outlets.
The strategy, launched in 2003, includes comment: “it [cold water pollution abatement] appears to be a clearly definable, tangible, cost-effective intervention that can be completed for the major storages in the Basin within ten years, through a combination of engineering and operating changes.”
Many workshops, technical papers and government reports have been written since the launch of the strategy and not one of these contradicts the original advice. However, not a single initiative that will practically address the issue of cold-water pollution has so far been implemented.
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References/Links
1. Native Fish Strategy for the Murray-Darling Basin 2003-2013
http://www2.mdbc.gov.au/__data/page/65/Fish-Strat_ful.pdf
2. Edition 34: Bringing back native fish
http://australianriverrestorationcentre.com.au/riprap-is-back-edition-34-bringing-back-native-fish/
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
One of the great adventures of my life was living out of a Canadian canoe on the Darling, north of the Menindee Lakes, for three weeks around Christmas 1979. We fished and shot as we went.
We never caught or even saw Murray Cod, and the river was full of carp. I remember a cocky called Ham was draining a billabong to send carp to the Chinese in Sydney. They were left writhing in the mud, hundreds of them, and just had to be picked up.
All of this happened after the soaking seventies, when drought was becoming a memory. I often wonder if a natural drought cycle wouldn’t have favoured the native species. Certainly, the Darling is equipped to run very, very dry, as we know from the 1800s on.
Old Man River…must know somethin’, don’t say nothin’…
Even our coastal rainforest streams are being invaded by carp. These once crystal creeks that were full of mullet, eels, dewfish and platypus are becoming milky and the natives are disappearing.
A local creek where a mate and I had previously logged 40 platypus, failed to show any on inspection the other day and then I suddenly saw this huge tail waving slowly in the murky shallows. Uh, oh.
Has anyone seen a dewfish nest in recent years? Those sand circles surrounding a central pebble mound used to be everywhere. They would have been in the Murray too, I would think, pre-carp.
They were the best fish you could eat. Other names, catfish eel, eel-tailed catfish, freshwater jewfish.
But what Robert says is right, dry periods would reduce carp invasion in the Murray. Even if this will never happen in coastal streams.
Jen – so can we have some clarity here as I’m not totally sure what you are saying:
(1) do you think there is a problem with native fish populations in the Murray system
(2) if so why – factors are?
(3) if there is a lack of clarity on the issue what can be done to inform the situation
(4) if the issue is clear that there is a problem what should we be doing
Just asking !
US Fish and Wildlife Service has been trying a similar strategy on the Colorado River for 20 years with exactly the same results. At some point you just have to allow the species to go extinct. Extinction is part of nature.
Swimming in the Murrumbidgee at Wagga Wagga the water was freezing!! you could only last a five minutes or so in the river otherwise you got a headache from the cold. It was as cold as the water at St Kilda beach in Dunedin, NZ.
Can’t imagine how fish could survive in it, but they did.
It’s my impression that whenever dams deliver water from deep down [cold], you can really smell the methane from the rotting vegetation in the bottom whereas when they deliver from the surface [warm] it is not noticeable.
It’s my impression that whenever dams deliver water from deep down [cold], you can really smell the methane from the rotting vegetation in the bottom of the dam as that methane-rich, very cold water hits the atmo whereas when they deliver from the surface [warm] it is not noticeable.
Anybody know if the methane is sequestered if left undisturbed in the cold water?
SD – they deliver from the bottom of the dams to get the head to drive the turbines for Hydro power. The Murrumbidgee is fed from the Tumut dam and the Burrinjuck Dam – both deliver hydro power.
Thanks John, but if they had a floating feed that took from the surface, wouldn’t the “head” be the same?
Yes – I asked myself that question – the column of water in a pipe from the surface would have a mass of water the volume of the pipe creating pressure at the bottom whereas the column from the bottom has a mass equal to the volume of the whole lake to create pressure. I’m ready to be corrected 🙂
No – that answer is wrong 🙂 Anyone have an answer?
Feeding from the bottom would deliver a bit more power in that it would be free of the friction of laminar flow inside a pipe leading from the surface. But I think a bigger pipe would overcome most of that.
However there is probably more to it because hydro dams all seem to feed from as low as possible. No doubt coming from low down is less complicated.
Well as Jen said – there was discussion about taking warmer water from the top so I must assume it’s feasible.
Hi Luke,
I’ve been saying there is a problem with native fish in the Murray for a decade. I thought government wanted do something about it. The MDBA and federal government more generally has spent billions of tax payer dollars but apparently with no intension of fixing the cold water pollution issue… I will explain why in part 3 of this series.
In the interim following is the abstract from my ‘Myth and the Murray’ backgrounder written and published in 2003, the same year that the native fish strategy was launched…
“We have all heard about the declining health of the Murray River, including poor water quality, dying red gums and threats to the continued survival of the Murray cod—this is the popular view in urban Australia. Along the river, communities believe that the end of commercial fishing, a substantial restocking effort, improvements in on-farm practices and the construction of salt-interception schemes have resulted in a healthier river. The available evidence supports the local view and suggests that, with the possible exception of native fish stocks, the river environment is healthy.”
Complete documents here: http://www.ipa.org.au/publications/449/myth-and-the-murray-measuring-the-real-state-of-the-environment
@John Sayers
this might, in part, explain the reason for taking water from the bottom of the dam
to feed turbines.
http://physics.ucsd.edu/do-the-math/2011/12/how-much-dam-energy-can-we-get/
Thanks Johnathan – I actually had read that link which is why I referred to the mass behind the force, but I wasn’t sure I’d interpreted correctly.
John, engineering wise it’s very simple to make a sliding inlet opening that always
keeps the intake level at a certain depth as the water level subsides.
However at the volume of water required for a power stations I’d be loath to start taking water at even 20 m below the surface. The speed of intake water would create vertices which would cause air to enter the pipes. Disaster!
But in a dam, the water at 20m wouldn’t be much warmer than at a 100m + anyway
and this would defeat the purpose.
Thanks Johnathan for explaining it – I understand the volume of water is large but the flow is slow so fish can move through the turbine safely.
Jennifer,
Interesting to see that you have picked up on cold water pollution. It is a major problem with irrigation dams – the engineers never thought to construct variable level off-takes. This was normal practice for water supply engineers. For example all of Melbourne’s deep dams have variable level off-takes.
The Hume, Burrinjuck and Mitta Mitta dams are the major sources of cold water pollution along the river, but this will be a summer based phenomenon, when these storages are stratified. I was the MMBW’s Water Chemist for eleven years, and the temperature of the water below the thermocline of the Board’s dam averaged 10-12C cf with surface temperatures of 20-25C. The dams on the Murray system will be no different. Also, the water below the thermocline was almost anaerobic. This is probably the case also in the Murray dams. However on release to the river oxygen recovery will be relatively rapid compared to temperature recovery to ambient conditions.
I grew up on the Murray in the 60’s. the Cod were around then but relatively scarce. We never caught a 50 pounder, although I saw many photographs from earlier years. I caught a couple 10 pounders though.
But the river has undergone other changes over the years.
I have revisited the river a number of times. There are vast areas being irrigated now that weren’t in the 60’s. the river is noticeably muddier than it used to be. Sure, it got muddy when the rice farms released water back into the river, but that was for a relatively short period. The river is much greener than it was back then. I haven’t looked at the data but I have always assumed this was due to increased algal biomass, probably stimulated by increases in nitrate and phosphate over the years. Again, I haven’t got the data.
What I have also observed is that the river doesn’t flood as often. When I lived on the Murray, the Hattah Lakes were lakes. The last time I visited them, about 8 years ago, they were dry beds invaded by young saplings. In the 60’s we swam there and paddled our canoes.
The river is a complex ecosystem that has also been invaded now by European Carp. When I fished there in the 60’s we mostly caught Red Fin, Bream, Yellow Belly, Catfish and the occasional Cod. Carp were relatively rare. Mind you the freshwater crays had an annoying habit of pinching the shrimp off your hook.
I had always understood that the breeding cycle of the Cod depended upon the flooding of the river. Of course research has discredited that belief. The fish spawns in the main channel.
But the fact remains that irrigation along the river has substantially altered the normal patterns under which the Cod evolved. Cold water releases have further exacerbated this variation. Combine this with the fact that Cod need time to grow before they spawn and in the meantime they have to compete with Carp, it is little wonder they are struggling to survive.
I was hoping Jen might enlighten us as to how power stations could produce warmer water…crickets.
It is my understanding that the outlets/valves for irrigation and hydro-electricity are different.
Jonathan, John, Luke et al.
I was going to include the following in my next The Land column on this issue/in this series… do you think i have been mislead… do you think that the real issue concerns hydro-electricity generation and associated limitation…
“Billions of taxpayer dollars have been spent: buying back water to improve the river environment; installing fishways so fish can swim up to just below the Hume dam; tonnes of micro-chipped logs have even been tipped into the Murray River immediately downstream of Hume dam to create the best possible habitat for Murray cod.
So why not address this remaining key issue [cold water pollution], indeed the issue identified as the most important and the easiest to implement ten years ago?
After reading everything I could find I tried my usual option of last resort – phoning a government bureaucrat. After some haranguing from me, it was finally admitted that it’s the trout lobby, the fly fish lobby – stupid!
They don’t want the cold water pollution fixed. The “eternal winter” is good for the European fish.
What a farce! So all the hundreds of millions of taxpayer dollars spent luring Murray cod up the river to just below Hume dam are to be wasted. Indeed they may simply hasten the decline of this majestic species because the river remains freezing cold – in an eternal winter – because the fly fish lobby trumps the native fish strategy.”
Jen, well there you are! If that’s not a totally revealing window into the total hypocrisy of the MDB green solutions I don’t know what is.
That should be broadcast all around the country.
That would be right – just below the Tumut Dam there is a trout hatchery and the local tourism ads are directed at the fishers.
http://www.visittumut.com.au/adventuring/fishing.aspx
I don’t think there is a difference between irrigation and power outlets on the dams. If they need more irrigation water they just produce more power sending more water into the river.
I was thinking one way they could solve the water temperature problem would be to create another lake downstream from the power stations, perhaps where the Tumut river and the Murrumbidgee join The inflowing cold water would sink to the bottom and the warmer surface water would them flow out the other end into the river.It would have to be a big lake to allow the water to get back up to normal temperature. They could fish for trout in the rivers above the lake and for native fish below.
Well it’s a bit ironic isn’t it Spanglers – you guys including Debs have been lecturing me for years on how dams are such good things for native aquatic fauna. Surely more water = more fauna right is what you’ve been saying. But when I tried to discuss well known issues of lung fish breeding habitat on dams, turtle smashing spillways you weren’t interested.
But now you are interested coz you think you can perversely give a backhander to the greens over MDB fish. Wow !
This is just too hypocritical in itself. Habitat and migration ability are important issues if you know anything about native fish.
So is the issue simply a failure to address the situation despite best efforts? More effort needed. Or a cynical waste of money.
Frankly re-engineering intake points from depth to the surface in an existing large impoundment structure does not sound simple to me.
And perhaps you’re just coming to grips with massive changes in flow regime on natural river systems can have unforeseen consequences.
Are the logs inconvenient for the boating fraternity?
And you lot have been telling me how great dams are for wildlife….
Anyway what’s the Cod situation above the dam?
Luke – the dam isn’t a problem for native fish, or trout for that matter, they thrive in dams, it’s the cold water created by hydro power that is the problem.
The Hume dam could easily be altered so irrigation water comes from the top, not the bottom as it only feeds a small hydro power station of 60MW. Nothing to lose there. That would fix the Murray River cold water problem.
The Murrumbidgee needs it’s Hume Weir also where the cold water from the power stations can warm back up to normal temps and as I suggested before that could be where the Tumut and Murrumbidgee rivers meet.
spangled drongo June 8th, 2013 at 1:58 pm
commented “It’s my impression that whenever dams deliver water from deep down [cold], you can really smell the methane from the rotting vegetation in the bottom of the dam as that methane-rich, very cold water hits the atmo whereas when they deliver from the surface [warm] it is not noticeable.”
SD methane (CH4) is a colourless, odorless gas. What you may smell from bogs, or decaying vegetation is some H2S (hydrogen sulphide). In piped natural gas (which is about 94% methane) is an added mercaptan. This has been added for safety (flammability) so that leakage can be detected. It is noticeable at about one part per billion and is not harmful at that level. There is no H2S in most natural gas and if there is at the wells it is removed by a cooling or liquefaction process.
From what I gather they don’t take from the bottom of the dam but have inlets around half way up the dam face. Still cold enough to create problems.
Thanks cementafriend. Yes it is that sort of pungent, rotting, smell.
Just found a comment from Peter S that was caught in pending… Now released but unfortunately stuck a bit further back up this thread…
Here’s a 2004 study on cold water pollution. They say there are nine dams causing major cold water pollution.
http://www.water.nsw.gov.au/…/desktop_assessmnet_cold_water_pollution.pdf.
Hi sd,
I may have spoken of it on here before, but I’m not sure.
At the end of the January before all the water hit Qld, there were heavy rains in NW NSW.
Prior to this downpour a yabby net in the huge billabong at Toorale Station, (on the Warrego, close to the Darling conjunction), came out packed with baby catfish . Also lots of other juveniles and little Warrego Crabs. And of course lots of fat blue yabbies.
When the rains came we had to get out quickly , with some of the slow movers needing to wade through an overflow form the billabong. There was a sea of water pouring toward the Darling across the flood plains.
The native fish know exactly what they are doing and when it should be done. When the big dry started , the carp were caught out all over the place in thousands.
I have not been back since Toorale was purchased as a National Park , but I believe that the wise people who grabbed it have found no way to dismantle the billabong infrastructure.
Gates on the river harvested small floods , while large ones spilled out onto a huge natural floodplain. It was all built around the 1890s by Samuel McCaughey, the “father” of Debbie’s MIA
Thanks Ian. Hey can you believe ol’ Flannelmouth! He’s now supporting that new paper on flooding in the MDB due to AGW after conning us into building desal plants because it was never gonna rain again:
http://www.abc.net.au/worldtoday/content/2013/s3778263.htm
Good grief Luke!
Re dams and benefits. . . .
On balance for goodness sake. . . ON BALANCE!
& the areas where we could make a positive difference in this part of the MBD is mitigating carp, redfin and cold water releases.
& good old mother nature has done far more re the Murray Cod than 10 years of Native Fish Strategy and $millions of tax payer funds. 🙂
Thanks Ian Thomson
Yes SD,
shifting goal posts?
I hope Graeme reports back?
A couple of additional points.
SD,
The methane produced at the bottom of dams is not sequestered. Most of it makes its way into the atmosphere. Likewise most of the methane generated in bogs and marshes is dispersed in the atmosphere. Methane is produced by anaerobic bacteria, chomping into organic matter in the absence of oxygen. Otherwise aerobic bacteria produce CO2 doing the same thing. These processes are quite natural and go all the way back to the origins of life. Deep lakes and artificial storages in temperate zones stratify in summer. As the surface water heats its density decreases and depending upon the surface area and wind strength and direction this creates a layer of warm water sitting on top of much colder water, with a rapid transition in temperature between the two over a relatively short distance, called the thermocline.
The effect is to minimise the mixing of the two layers. Aerobic activity in the cold layer continues until the dissolved oxygen is depleted and anaerobic activity takes over, generating methane and H2S, among other things. Depending upon the buffer capacity of the water a significant drop in pH, as much as one unit, can also occur. This is usually accompanied by an increase in dissolved iron and manganese, promoted by the zero oxygen environment and also the low pH. These conditions induce a chemical reaction, called reduction, whereby insoluble ferric and manganic oxides and hydroxides are converted into water soloble ferrous and manganous forms.
In the case of potable water storages, where the water is usually transported long distances via pipelines, engineers construct multiple level off takes so that when the storage is stratified they can avoid the anaerobic layer. Drawing water from this area can promote the development of iron and manganese slimes on the inside of the pipes, which over time significantly reduces their carrying capacity. Also water from the anaerobic can cause “dirty water” and taste and odour problems for consumers.
In nutrient rich storages multiple level off takes also allow engineers to avoid algal blooms, which are generally confined to the surface few metres, where light intensity is greatest.
These considerations are of much less importance in irrigation and hydro-electric storages. Also the required discharge capacity of these storages is generally much higher than for potable water storages. Therefore a variable off-take system is necessarily much more substantial and therefore more costly. Retrofitting such dams with variable level off-takes is not impossible. But it would certainly be very expensive.
John Sayers,
Water extracted from the surface and delivered to a turbine will have the same head pressure as water extracted from the bottom less any head losses resulting from the additional length of pipe involved. Given the design of most variable off-takes, which are effectively tall cylinders sitting vertically on the reservoir bottom, with moveable gates at different levels, then the head will fall if lower gates are used, unless the gate is large enough to allow a flow into the tower which is significantly greater than the discharge from the base of the tower. But with adequate design, any head difference will be minimal.
Just rough rules of thumb.
HI Jennifer, when I visited Chico in California I noticed dams above the valley floor and asked about them as they were not very deep. The answer was that water from the big storage dams was too cold for irrigation and the water was released to the shallow dams to warm up before being used for irrigation.
They grow lots of rice in central California.
So this has been a complete waste of money, the problem seems to me to be ego tripping so called experts yet again getting it wrong at the tax payers expense