‘Pink Lake’: the secrets of Canberra’s hidden natural phenomenon

Damien Larkins 24 September 2021 23
'Pink Lake' in Bruce

The naturally occurring ‘Pink Lake’ in Bruce is quite a spectacular sight. Photo: Michelle Kroll.

Dubbed by locals as ‘Pink Lake’, one of Canberra’s brightest hidden secrets is in full bloom again.

The naturally occurring pink body of water lies hidden among trees in Bruce, across the road from the University of Canberra.

The bright colour makes for an unusual sight in the bush capital, and is a favourite of local photographers.

The pinkish hue comes from azolla pinnata, an aquatic microfern that is native to Australia.

READ ALSO: ‘Psychedelic photography’ captures Canberra in unusual pink light

“It looks great,” says Danswell Starrs, a water scientist with the ACT Environment, Planning and Sustainable Development Directorate.

“It’s an interesting focal point for the community. There’s definitely an active community that has an interest in it, and it’s clear from social media that it’s very popular.”

The body of water is one of two stormwater runoff ponds off Eardley Street in Bruce.

They collect water from Calvary Hospital and the nearby Canberra Institute of Technology campus.

Duck and ducklings swimming on 'Pink Lake' in Bruce

The pink microfern, azolla pinnata, poses no issues to creatures such as fish, or this duck and its ducklings. Photo: Michelle Kroll.

Danswell says while the pond’s colour comes and goes, it is predominantly pink for most of the year.

“It can be anywhere between green in colour, right through to ‘reddy-brown’,” he says. “It depends a little bit on the species.

“The more sunlight they get, the more red they tend to be.”

Azolla pinnata prefers still-water conditions, and especially thrives in the days after rain fills the ponds.

READ ALSO: Native birds are battling for dwindling tree hollows as spring sets in

“If you get periods of generally quite unstable conditions, or the pond dries up, then obviously it disappears, but it can bounce back really fast,” says Danswell.

“In really good growing conditions, it can double its biomass in just two days.

“It has the potential to spread and take over that pond in a very short period of time when conditions are right.”

It’s that rapid growth that sees the microfern used as a source of protein for commercial chicken feed and in the aquarium industry.

“People do like it because it can be quite attractive,” says Danswell. “You still have fish and all your other aquatic organisms living naturally in association with it.”

Pink microfern, azolla pinnata, on lake in Bruce

The microfern, azolla pinnata, also has commercial uses. Photo: Michelle Kroll.

Research has found the microfern also absorbs heavy metals, giving it potential uses in bioremediation, a process that uses microorganisms to break down pollutants.

But while it does have commercial benefits, it’s not about to provide an extra income stream for Canberra.

“Maybe if we had hundreds and thousands of stable ponds specifically set up for harvesting azolla then maybe somebody could do it,” says Danswell.

“But you probably wouldn’t want to take away from the Bruce pond as being the ‘Pink Lake’. The community might not like losing their unique status.”

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23 Responses to ‘Pink Lake’: the secrets of Canberra’s hidden natural phenomenon
Sandii Hardii Sandii Hardii 9:18 am 29 Sep 21

I don't think this is good for the wildlife.

    Timothy Bailey Timothy Bailey 10:11 pm 30 Sep 21

    The ducks seem to like it. Are they not wildlife? it is a natural phenomenon, no?!

Lucy Cameron Lucy Cameron 7:32 pm 28 Sep 21

Jaimee Wallington let’s walk here

Belle Holmes Belle Holmes 1:29 pm 28 Sep 21

Bella Martyn-Thompson the lake near your house 😂

Tina Connor Tina Connor 7:28 pm 27 Sep 21

Sam, the pink pond!

Sumaira Ikram Sumaira Ikram 2:06 pm 27 Sep 21


Melanie Pzoolé Melanie Pzoolé 7:43 pm 26 Sep 21

Joe G Dubya we should go

Tim Reardon Tim Reardon 7:33 pm 26 Sep 21

flourescent poo?

Daniel Carson Daniel Carson 4:37 pm 26 Sep 21

Alex Pan come baaack

Emily Drown Emily Drown 2:25 pm 26 Sep 21

Another fun fact for you Chi Sobs

Daniel Carter Daniel Carter 1:35 pm 26 Sep 21

Nick Porter Lu Chen what a beautiful lake 👀

Lela Bodo Lela Bodo 10:52 am 26 Sep 21

That lake is now famous 😂 Jeremy Scerri

Rommel Gausman Rommel Gausman 9:30 am 26 Sep 21

Azolla. It's a water fern. We tend to clean it oout of our dams as it'll choke out all the other plants. Worst case, it overgrows and causes mass oxygen depletion. The chickens seem to like it.

Scott Harvey Scott Harvey 7:19 am 26 Sep 21

There's another pink pond on hidden UC grounds.

Amy Dale Amy Dale 10:36 pm 25 Sep 21

Bec Grintell get there!

Tracy Gorman Tracy Gorman 10:35 pm 25 Sep 21

Used to be lots of yabbies in those ponds.. wonder how they cope with the pink stuff?

Michael Parker Michael Parker 9:16 pm 25 Sep 21

Scott Hancock what’s on your dam

Maddie Ten Maddie Ten 9:11 pm 25 Sep 21

Man made not natural

    Robyn Holder Robyn Holder 2:29 am 26 Sep 21

    Maddie Ten yes like all the other ponds and lakes in Canberra. Beautiful.

Katie Ray Katie Ray 8:43 pm 25 Sep 21

Rayzor Ray how pretty. Should go

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