Nhill Lake dyed blue to prevent growth of poison algae

ABC NEWS (Australia)

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.

Transcript

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.

04:26 [BLANK_AUDIO]

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