The Lake ever more closed

martyo said :

An image I grabbed last month of the lake. I thought at the time it must of been a green light I did not see – http://www.flickr.com/photos/buglogic/7272734118/in/photostream

great shot Martyo. The soylent colour does add a certain something

snoopydoc said :

@ Gungahlin Al

Actually, it seems most people (or at least most local authorities) tend to grossly _overestimate_ the dangers of cyanobacterial blooms (they’re not algae, guys) in recreational waterways.

🙂 Thank you, Snoopydoc – an example of TRA at its absolute best!

An image I grabbed last month of the lake. I thought at the time it must of been a green light I did not see – http://www.flickr.com/photos/buglogic/7272734118/in/photostream

HenryBG said :

Tetranitrate said :

AAMC said :

Drain the Lake, clear out all of the sediment and organic matter….should fix the problem for a while.

No doubt it’d probably solve a few missing persons cases as well.

Perhaps find that missing Rueger at last. Unless the cops already did find it and aren’t telling us about it….

The time to drain the lake was during the drought when the Federal refused to renegotiate its water access rights with the ACT government. Would have greatly assisted the ACT’s negotiations. Typical useless local pollies missed a golden opportunity there.

Very good point. Unfortunately NCA control the lake not ACT govt. Sooner or later they have to drain the thing. Im sure it will look like the combination of a carpark (cars/shopping trolleys) and a graveyard. And then get some smarts on how to keep the water quality at non-toxic levels for the future.

AAMC said :

djk said :

And build a heap of units?

um, no…….even if the dam was removed totally it is still a water course, so no units unless they can float.

He didn’t say they had to be NICE units…

@ Gungahlin Al

Actually, it seems most people (or at least most local authorities) tend to grossly _overestimate_ the dangers of cyanobacterial blooms (they’re not algae, guys) in recreational waterways.

The current culprit, Anabaena circinalis, is known to elaborate predominantly two main types of toxin: anatoxins and saxitoxins.

– Anatoxin-a is a neuro-muscular transmitter (ACh) analogue that works in a similar way to neuromuscular blocking drugs that are used to paralyse patients for surgery (don’t worry, you’re asleep when it happens). 😉

– Anatoxin-a(s) works in almost the opposite way (it stops you breaking down your own neuro-muscular transmitter; it’s an anticholinesterase) but the end result is the same. Although, to be fair, this particular toxin will also make you get all dribbly, get a bit shaky, and diarrhoea in your daks first.

– Saxitoxin works by blocking certain types of sodium channels, and hence turns “off” your nerves, in high enough concentrations.

The practical upshot of all of these toxins is that you essentially become paralysed, can’t breathe, and therefore drop dead. They are all _very_ potent toxins… you only need a tiny bit to do you in. However, it’s _really_ hard to get that tiny bit into you, even if the lake is brimming with these cyanobacteria.

There has never been a single case… ever… in Australia of a person being harmed in any way by cyanobacterial toxins in a recreational body of water. The only deaths that have occurred have been the result of dense blooms occurring in _drinking water_ supplies, and only then after those blooms were destroyed with poison. The toxicity of contaminated drinking water to humans is _much_ higher when the cyanobacteria have fallen to bits and released the toxins into the surrounding water. This also happens (typically) at the _end_ of a warm/summer season when the conditions are no longer favourable and the cyanobacteria all cark it at about the same time, releasing a _lot_ of free toxins into the water.

The proposed possible link between another, quite different, cyanobacterial toxin known as BMAA (beta-methyl-amino-acid) and long-term neurodegenerative diseases (particularly something nasty known as amyotrophic lateral sclerosis or ALS) is speculative at best, and indeed a recent review article looking at the evidence to date (which has pretty much just been epidemiologic guesswork based on spatial clustering) concludes that there is no clear evidence of a link between any environmental factor, including cyanobacterial blooms, and diseases such as ALS:

http://www.ncbi.nlm.nih.gov/pubmed/22214351

With regard to how much lake water you’d have to drink (this stuff _can’t_ get in through your skin) to pose a danger to you, the estimates are highly variable, and dependent on the concentration of both cyanobacteria themselves in the lake, and whether they’re all getting a bit dead and leaky or are still in good health, but even conservative back of the envelope calculations would have you knocking back _litres_ of lake water before you’d expect problems. Having said that…

** PLEASE DON’T GO AND DRINK THE LAKE WATER **

The probability that you will suffer cyanobacterial toxicity from any activity, including swimming, that doesn’t involve swallowing rather a _lot_ of the lake, is astonishingly small. The authorities are just being risk-averse and overly cautious, though it’s interesting that they hedge their bets and allow “secondary” activities on the lake but forbid swimming. Unless you’re already drowning, or have a real sweet tooth for the lake water and like to swallow cupfuls of it at a time when splashing about in the water, swimming in the lake is not dangerous. Well, at least not from the cyanobacteria.

And seriously…. not swimming in the lake since the 1970’s or 1980’s? Pick your days and your spot… I’ve been swimming in it over the past few summers with no problems… 🙂 Though most of my intimate encounters with the lake water have been of the more unintentional kind when falling off my paddleboard… 😉

Ultimately, you get the environmental protection that you pay for in society. In the case of Australia, noticeably the ACT, it’s not much. This sort problem has been solved elsewhere, e.g. Lake Washington in Seattle. It takes a change of ways, like reducing fertilizer on lawns, changing detergents, and altering drain flows…Does the ACT have the will to fix this problem? Likely not. So it’s time again to spend some money for another worthless study from consultants!

shirty_bear said :

Seems odd to have happen now …

Yes it does.

A major cause of algal blooms is streambank erosion. Could the current problem be related to the removal af all vegetation on the banks of the Molonglo for several kilometres upstream? Man, they changed that river from a beautiful, functioning (though non-native) ecosystem into a moonscape.

But I bet that’s one hypothesis they don’t look at too closely.

watching some old footage last year about the building of the lake, it was meant to be a haven for the locals, swimming, boating etc. its a shame that it is like this now. I remember swimming in it at black mountain peninsula as a kid, I wouldn’t put a foot in it now.

It would be interesting to see it drained. Lots of interesting things I’m sure!

chewy14 said :

rosscoact said :

shirty_bear said :

Seems odd to have happen now … we’ve had plenty of water flowing through and it hasn’t been hot.
And there’s two solarbees doing their darndest, right?

Surely the Canturf farm at the top of the lake has a hand in this? I don’t notice other lakes in the area being similarly affected right now …

I think you’re on the money there. Has the nutrient leaching from Canturf ever been assessed?

Not even close. Have a look at the catchment area of the lake. Canturf is a pimple on the fleas arse on the dirty dog that is the water flowing in to LBG.

Canturf has been there for ages I cant see that being the main problem it was as others have said it was since the heavy rains so its some were up stream but also as its a dam the sediment builds up over time so maybe its reached a point of saturation so to speak.