She’s the jewel in the crown of our Manly tourist offering and a firm local favourite – a marine reserve and the only west facing beach on the NSW coast – but our gorgeous Shelly is, sometimes, frankly full of sh*t (or something like it).
Manly’s Shelly Beach has landed among the bottom ten swim sites in Sydney in this year’s annual report on water quality results, examining real pollution samples from October 2024 to October 2025.
But it’s mostly good news for the region, boasting nine of Sydney’s top ten cleanest swim sites in the 2025 State of the Beaches report, released by the NSW Government this week.
Three other sites around Narrabeen Lagoon and the Pittwater also ranked poorly, showing that even in a region known for its pristine coastline, some areas still suffer.
The state’s Beachwatch program monitors water quality at 249 swim sites across NSW, measuring levels of Enterococci bacteria.
These organisms are commonly found in soil, water, food, sewage, and in the intestines of animals, and can cause stomach issues and infections.
Concentration of these bacteria are used as an indicator of faecal contamination, which can often coexist alongside harmful E. coli.
According to the National Health and Medical Research Council, water is considered safe for swimming when Enterococci levels remain below 41 colony-forming units (cfu) per 100 millilitres. Anything above that threshold increases the risk of illness.
At Shelly Beach, the average (mean) reading was 79.4 cfu/100mL, nearly double the safe limit. Still, regular swimmers told Manly Observer they had never fallen ill and continue to enjoy the spot year-round.
It is generally well known to avoid swimming in beaches for up to three days after heavy rain ( 24 hours the hard and fast rule). The stormwater outlets that flow into locations like Shelly Beach, Queenscliff and Clontarf can become overwhelmed during heavy rain and sewage can overflow into the stormwater system when the sewerage system becomes overloaded with extra water entering through cracked pipes, faulty joints, and direct connections.
“I have swum here for many years, and I have always found it to be very clean. I have never got sick from swimming in the water and so it is difficult for me to believe that is it one of the worst in terms of pollution,” said Sue Barnes.
Johnny McPike said: “Ultimately on a really stinking hot day, when you want to escape the heat. It is an individual thing, I think myself, I would hop in then crawl up and try to keep my mouth closed.”
Manly Observer conducted its own data analysis to produce a ranking of Northern Beaches swim sites, from best to worst, based on the median level of Enterococci bacteria (cfu/100mL) recorded over the past year.
Avalon Beach topped the list with 0% of readings exceeding 40 cfu/100mL, though several other beaches came close behind.
Statewide, the report found 76% of swim sites were graded Good or Very Good, meaning they were suitable for swimming most or all of the time. An improvement on last year’s results.
Although hard to believe after the rain we experienced in August, officials attribute the stronger performance to average and below-average rainfall and the addition of new monitoring sites.
Ocean beaches performed particularly well, with 95% rated Good or Very Good in 2025, comforting news for keen swimmers and surfers.
Even so, experts warn that heavy rain can quickly change conditions, as stormwater runoff and sewage overflows can temporarily spike bacterial levels, increasing the risk to human health.
On the advice of Beachwatch, the Council recommends staying out of the water for at least one day after wet weather at ocean beaches, and up to three days at estuaries and lagoons.
The good news is that in most cases tidal fluctuations take the pollution away no sooner than it appears, so even Smelly Shelly smells sweet again soon enough.
