What was once one of Sydney Harbour's most polluted areas is on track to open as a swimming spot next summer.
A machine, with close to real-time water quality monitoring, will determine when it's safe for swimmers to take a dip.
The set up at Pirrama Park in Pyrmont will test the water quality every 15 minutes in a trial of new technology that will be key to expanding swimming areas in the harbour and the Parramatta River.
"This is a marked improvement to the previous procedure of having water samples manually collected and brought back to the lab for water-quality testing, which took three days for a result," Sydney Water's head of western Sydney development Renee Ingram said.
The $70,000 ColiMinder, which cost another $160,000 to install, is already operating at other urban swimming sites in Europe and North America and will be used at the 2024 Paris Olympic Games to monitor water quality in the Seine for the triathlon.
Pyrmont was one of the harbourside locations identified in a 2019 report from Andrew Burges Architects, commissioned by the City of Sydney, looking at ways to create a swimmable harbour.
"Today we're a significant step closer to opening our first harbourside swimming location with the introduction of the ColiMinder," Sydney Lord Mayor Clover Moore said.
The council has already factored in water access with steps down to the water.
"When the city built Pirrama Park, we future-proofed this possibility in its design and construction, so the addition of a swimming pool would only require minimal infrastructure along the existing harbour edge," Cr Moore said.
Exciting time for urban swimming
Swimming in the inner-city area that lies just to the west of the Sydney Harbour Bridge was once unimaginable.
Along with Balmain and Glebe, it hosted the majority of Sydney Harbour's waterfront industry, from whaling in the early 1800s to the abattoirs, soap and detergent factories that came later.
"Up until the early 1970s there was a lot of industrial waste, industrial pollution going into the harbour and Pyrmont was really impacted by that," water quality expert Professor Stuart Khan said.
Since regulations were introduced to control industry pollution and sewerage systems improved, efforts have been underway to rehabilitate the marine environment.
Professor Khan, from the University of NSW's School of Civil and Environmental Engineering, said it was an exciting time for urban swimming in Sydney.
"It's a huge turnaround to actually see this environment as a place to come down and enjoy," he said.
"We didn't think Pyrmont was a location that people would want to live, let alone swim."
He said last month's opening of Bayview Park in Concord in the inner west showed swimming in the river and harbour was possible.
Variable water quality
The ColiMinder machine measures enterococci levels in the water, which are linked to gastrointestinal illness. It will also be able to detect pollution incidents early.
Professor Khan said the near real-time tests were important given the conditions at Pirrama Park could change significantly with tides, rainfall and human activity.
While it's too early to assess the results from the ColiMinder trial, authorities are confident the water will be ready for swimming soon.
Sydney Water has upgraded the wastewater system around Pirrama Park to prevent stormwater entering and causing surcharges of pollution.
The council is also working on reducing stormwater pollution entering the harbour, including installing rain gardens, wetlands and swales across the network.
For now, people are advised to hold off from jumping in at Pyrmont.
"Our lab results show that water quality is variable," Ms Ingram said.
