Australia's capital city has a problem so big it can be seen from space.
Like many waterways around the country, the city's Lake Burley Griffin has well and truly turned green.
Blue-green algae blooms are a natural phenomena but can prove deadly for some elements of the natural ecosystem and can even be toxic to humans.
"I haven’t actually seen it as bad as this previously," said Janet Anstee, a senior experimental scientist with the country's peak science body, the CSIRO.
"When I was walking around the lake the other day ... it stunk," she told Yahoo News Australia.
Ms Anstee is working on a project with Digital Earth Australia to establish a national mapping approach to allow water management agencies across the country to better monitor water systems through the use of satellite images coupled with sample analysis done in the field.
The idea is to build models to allow for early detection and improved data sets over time, particularly outside of built up areas.
“With satellites going overhead all the time, a manager of a waterway could look at that and might have some levers they could pull to improve water quality or put out alerts,” she said.
Ms Anstee is also trawling through historical data to identify trends and better understand the scale of algae blooms, in the wake of highly publicised events in the lower Murray Darling, blamed for mass fish kills.
"They [algae blooms] seem to be" getting bigger, she says.
“One of the things we’re trying to do with GeoScience Australia is answer that question.”
In the field to collect samples in Burrinjuck, north of Canberra, last week, she described the scene on the water's surface as "disgusting".
"The bloom in Burrinjuck is just disgusting, it’s really foul," she said.
Pea (Microcystis ) soup on Burrinjuck- CSIRO’s field crew taking samples yesterday 10/3/2021 pic.twitter.com/OIIR7p4Nif
— Janet Anstee (@AnsteeJanet) March 11, 2021
More research required to understand toxicity
Lake Burley Griffin in Canberra is regularly plagued with the algae, with an extreme alert issued in January while last week the ACT government issued a similar alert for Lake Tuggeranong, further south in the city.
"Contact with algal scum should be avoided," it said in a statement. "Clothing that has been in the water should also be washed to remove any blue-green algae residue.
"Symptoms of blue-green algae exposure may include skin, mucosa and eye irritation, flu-like symptoms, hay fever-like symptoms and gastrointestinal illness."
According to the ACT's government's environment department, there are actually three types of blue-green algae which generally occur at different times of the year.
"They are all toxic to dogs when ingested and potentially hazardous to humans."
Ms Anstee says more is needed to understand why – and at what point – the cyanobacteria, or blue green algae, turns toxic.
"They're not necessarily toxic all the time," she said.
“We don’t really know what the trigger is to take the cyanobacteria and make it produce the cyanotoxins. So management authorities have to take a very conservative approach."
Do you have a story tip? Email: email@example.com.