More than 4000 Olympic swimming pools worth of sewage was released into Brisbane waterways in just 12 months, with testing of popular creeks frequently finding bacteria levels more than 10 times higher than what is safe.

An 18-month investigation by “Stop Raw Sewage Into SEQ Waterways” has uncovered more than 10.5 billion litres of untreated sewage was discharged by Urban Utilities into waterways including the Brisbane River and local creeks between July 1, 2024 and June 30, 2025.

A further 7,291 releases over that time did not recorded volume, meaning millions more litres of untreated sewage could have been discharged.

“When we’re talking 4320 Olympic-sized swimming pools of untreated sewage over a 12-month period, I think that is absolutely inexcusable,” Stop Raw Sewage group founder Adam Bowden said.

“I don’t believe that any community should have to accept that level of pollution entering our waterways.”

Brisbane City Council monitors the levels of entercocci — a faecal bacteria — at locations including Moreton Bay, the Brisbane River, Sandgate, Shorncliffe, Cabbage Tree Creek, Nudgee, Wynnum, Lota and Oxley Creek.

Between July 2025 and June this year, the program detected bacteria levels more than 10 times higher than what is considered safe 21 times, with Oxley and Cabbage Tree creeks, and the Lota boat ramp the most contaminated.

Between July 2024 and June 2025 levels were extremely high 20 times.

Just last week signs were erected by council at Shorncliffe warning people to avoid contact with the water.

A council spokesman said: “As multiple factors can influence water quality, we cannot attribute individual test results to a specific source”.

Mr Bowden said as well as health risks for residents, poor water quality was also impacting marine life.

A recent Right to Information request revealed 282 marine turtle deaths had been recorded between January 1, 2025 and January 20, 2026 — an average of 21 per month — the cause of death in 212 of the cases “undetermined”.

Photos provided to the Courier-Mail by the Bribie Island Turtle Trackers Association Inc show dead animals — many juveniles — covered in moss and barnacles, indicating ill health, while others had missing limbs or obvious signs of shark attacks and boat strikes.

“Water quality across Moreton Bay is in decline and so are seagrass beds — the number one food source for the sea turtles,” he said.

“It begs the question if it is coinciding with the amount of untreated sewage we’re having pour into the waterways.”

An Urban Utilities spokeswoman said “significant and frequent rainfall events” between July 2024 and June 2025, including Tropical Cyclone Alfred, increased stormwater inflows into the wastewater network and consequently increased wet weather sewage releases.

“The majority of these releases occurred during larger wet-weather events, when a range of other catchment sources also contribute comparatively larger loads to waterways,” she said.

“ … Our network is designed to manage predictable flows of wastewater, not sudden surges of stormwater.

“Wet weather releases are heavily diluted by stormwater and used when necessary to prevent wastewater from backing up into homes, businesses and streets.”

Urban Utilities is required to notify Queensland’s Department of Environment of significant sewage releases, which are investigated.

Only one enforcement action against Urban Utilities relating to unauthorised sewage discharges into the Brisbane River in 2024 is on the public register.

A Department of Environment Media spokesman said: “We work closely with Urban Utilities to ensure it meets its obligations and that water quality information is published for community access and transparency”.

The Urban Utilities spokeswoman said $6.7bn would be spent on infrastructure over the next decade to upgrade the water and wastewater network.