A popular recreational creek in northern Brisbane regularly records dangerous levels of faecal bacteria in council testing, but many people using the waterway have told the ABC they know nothing about it.

Council water pollution advice: Avoid contact with water from Cabbage Tree Creek for three days after heavy rain

Avoid contact with water from Cabbage Tree Creek for three days after heavy rain Avoid all primary contact with the waterway, including activities in which bodies are immersed, faces or other body parts are frequently immersed

Avoid all primary contact with the waterway, including activities in which bodies are immersed, faces or other body parts are frequently immersed Avoid activities in which where faces are frequently wet from spray and water can be swallowed or inhaled

Avoid activities in which where faces are frequently wet from spray and water can be swallowed or inhaled Avoid water contact to ears, nasal passages, or cuts in the skin

Experts warn exposure to the dangerously high levels of enterococci bacteria recorded in Cabbage Tree Creek could cause urinary tract, ear and skin infections.

The Brisbane City Council regularly tests all the city's waterways for pollution.

Levels of enterococci above 40 per 100 millilitres are considered a risk to human health, according to national guidelines spelt out on the BCC water monitoring website.

Last October, tests recorded a dangerously high pollution level of more than 16,000 organisms per 100mL in Oxley Creek in Brisbane's south-west.

Then a month later, Cabbage Tree Creek near the popular Boondall Wetlands recorded an enterococci pollution level of 14,000 — 350 times the safe limit.

While this was a spike in the pollution level, water in the creek regularly exceeded the safe limit for faecal pollution, with BCC estimating its long-term pollution average to be 563 faecal organisms per 100ml.

Biomedical expert Professor Flavia Huygens from the Queensland University of Technology said those results were particularly concerning for Cabbage Tree Creek, which is used regularly by canoeists and recreational fishers.

"Anything above 500 organisms per 100mL of water is considered to be a risk to people who are exposed, so 14,000 organisms is definitely a very high risk for contracting some form of illness," Professor Huygens said.

"There have been many reports in the past where water contamination has caused public waterways to be shut down."

Members of Sandgate Canoe Club regularly paddle along Cabbage Tree Creek. ( Facebook Sandgate Canoe Club )

For the past five years the northern Brisbane waterway has experienced consistently high levels of the harmful bacteria.

Cabbage Tree Creek's pollution level spiked again on May 10, when BCC recorded 7,300 organisms per 100ml.

The water is tested monthly in winter and fortnightly during summer months.

But Ben Jones, who lives two houses from the council's testing site, said he had been unaware of the problem.

"We've never heard anything about it, not even from the neighbours but definitely not the council — I had no idea," he said.

He said his son regularly went fishing at the testing site.

Cabbage Tree creek often records high bacteria levels. ( ABC News: Zoe Coleman )

BCC environment committee chairman David McLachlan said information about the bacteria threat was on the council's website.

"If people are interested or want to know what the condition of the waterway is, they're encouraged to go to the council website," he said.

Signs in the area warn of the presence of bacteria and increased levels after heavy rainfall.

Volunteer Marine Rescue Brisbane president Thomas Grice said no-one was ever contacted when high levels of bacteria were recorded in Cabbage Tree Creek.

"If there is an issue, people who enjoy the creek should be made aware of it, to be careful," he said.

"Especially in this day and age — there are plenty of ways to inform people and communicate with people."

Phil Plant said putting pollution warnings on a council website was not good enough. ( Supplied: Phil Plant )

Phil Plant from Sandgate Canoe Club agreed BCC should be doing more to inform the public.

"You do have to go and find the information, so it is not particularly transparent," he said.

"It would be good to have some sort of warning system in place if they do have high readings rather than just taking a few days and putting on the website."

Councillor McLaughlin said he was willing to consider ways to improve awareness.

"If there's a need for better education about what happens after heavy rain events in our creek systems, I'm happy to take that forward as a recommendation," he said.

What is causing the high levels?

Queensland Urban Utilities (QUU) owns and operates the Sandgate Sewage Treatment plant adjacent to Cabbage Tree Creek.

Spokeswoman Michelle Cull said the effluent released into the creek was monitored regularly.

"The water is tested for a number of different things including the enterococci," she said.

"UV disinfection kills the bacteria in the waste water, so it is treated to a very high level."

Many people who regularly used Cabbage Tree Creek told the ABC they had no idea it could be heavily polluted. ( ABC News: Zoe Coleman )

A 2012 QUU and BCC report showed the bacteria was predominantly caused by bats and horses, but there has been no further testing to confirm the source of recent bacteria levels.

Under its environmental licence, QUU is permitted to bypass the total water treatment process in heavy rainfall.

Ms Cull said during a bypass the water was not tested before being released into the creek.

"If a bypass does occur, the waste water is heavily diluted by storm water and it has also undergone partial treatment, including screening and removal of grit," Ms Cull said.

She said the bypasses "potentially contribute to bacteria levels in the creek".

A bypass occurred last November, the day before pollution was found to have spiked in Cabbage Tree Creek.

Professor Huygens said the water should be tested weekly and that BCC needed to determine the "disease-causing ability" of the enterococci levels.