A town in the west of Victoria has dyed its lake blue to cool it down and prevent the growth of blue-green algae. The man-made Nhill Lake was created in 1960 and has always looked pretty good now with the addition of 20 litres of blue dye, its looking more attractive than ever.
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00:00 The lake's been in existence longer than I have, so even as a kid we used to muck around
00:08 down there and it's had several reincarnations in the last five decades, generally to do
00:13 with when we've had significant rainfall events, but it's got a little bit more control
00:18 about it now and the last few years I walk around it every morning with my dog and the
00:25 local lake committee's been putting a lot of work into it to bring it back up to spec.
00:30 As you'll see there it's looking nice and full and blue now.
00:33 Indeed, so when did problems start emerging with blue-green algae?
00:38 The last couple of years we'll say sort of from 2017 onwards when the water flow wasn't
00:46 quite as controlled, so the level would get low over summer, the water would heat up and
00:51 then that's the ideal conditions for an algal bloom and there was an incident there a number
00:57 of years ago where there was actual blue-green algae so essentially the lake was shut down.
01:04 And so the lake was off limits then for how long?
01:09 Essentially a year and in that time it dried out so you could still walk around it but
01:15 it just became a walking track around an empty dam so that wasn't as attractive as it is
01:22 now.
01:23 And so what do you reckon of the solution?
01:27 The move by the lake committee to adopt the approach of keeping the lake full and then
01:33 addressing any incidents of an algal infestation by using the food colouring essentially is
01:42 what it is, has made a great difference and also being able to have the, on the odd days,
01:49 to have the boats down there, that also stirs things up which has a great result as well.
01:55 And so they're pumping water into it are they to keep it full?
01:59 That's right so it's getting a trickle in, we've had a significant summer rainfall events
02:04 up here which has helped so it naturally harvests water and we're also sitting on an abundant
02:10 aquifer in this nil district and that's trickling in there, it sort of compensates for the daily
02:16 evaporation, it's keeping up quite well at the moment so we don't have to worry about
02:21 the level dropping and as soon as the level drops you start to get a natural increase
02:26 in temperature so that's been abated by this move.
02:29 And so it only needs 20 litres of this, what you say, what you describe as food dye to
02:35 get this sort of, is that 20 litres a year?
02:39 I would suggest that it could be every two or three months, obviously over summer is
02:45 when you want to be most prudent with it but it'll take more than one application to keep
02:50 it that fresh year round.
02:53 Yeah but I'm surprised it's that little even over two or three months.
02:58 Yeah so it's not a great amount, obviously it's a concentrate that goes in just like
03:04 making cordia but the result as you see there, that's not many days after the application
03:12 went on, it'll wane as time goes on but it didn't take a long time for them to do it,
03:18 to apply it and it's one of those things, it'll be put on pre-emptively so that the
03:27 organisms don't get a chance to prosper, it has no effect on the aquatic life in there,
03:33 there's still yabbing going on, there's still people fishing, getting nice fish out of there,
03:39 so it's just a positive move all round.
03:41 Yeah so and officials say there's no dangers or environmental side effects with this dye
03:46 at all?
03:47 No it has no hazardous consequences at all, it's totally 100% safe.
03:55 And Marty so before we let you go, would you like to put a call out for people to duck
04:00 into Nill if they're driving by and take a look and spend a bit of money in the local
04:04 economy?
04:05 Definitely, look we're on the main road from Melbourne to Adelaide, there's thousands of
04:09 vehicles pass through here every day, there's easy access to that lake to drive down there
04:16 and park, there's a beautiful walk all the way around it so all you need is, it's only
04:20 a 10 minute walk and look if it's a hot day, pack your togs and a towel and go for a swim.
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