CRESSBROOK Dam remains closed for water activities until further notice while the Toowoomba Regional Council manages an outbreak of cyanobacteria, which is a form of blue green algae, that was detected in early February.

Councillor Joe Ramia said that while it was sad that Easter holiday makers couldn't enjoy recreational activities on the dam, it is a priority of the council to ensure public safety.

"You can still go to Cressbrook to camp or enjoy a picnic but water based activities are strictly prohibited," he said.

"The great news for holiday makers is that Cooby Dam is open to boating, fishing and picnics and camping at one of the private campgrounds.

"It is important to keep an eye on the council's website to view the current status of lakes and dams in the region."

Councillor Bill Cahill said the council would continue to conduct its regular testing regime to determine when the dam could re-open for regular water-based recreation pursuits.

"The cyano bacteria presents no risk to drinking water supplies as it is removed by the water treatment and disinfection process," he said.

"The council monitors the three dams on a weekly basis for algae and numerous microbiological parameters including E.coli. We also test chemical parameters such as iron, manganese, alkalinity, hardness, ammonia, nitrate, colour, turbidity and phosphate.

"The treatment process is also closely monitored daily. When the water leaves the treatment plant we conduct tests in the distribution system in accordance with our Drinking Water Quality Management Plans.

"These plans line up with the Water Supply Safety and Reliability Act 2008."

To view activities open or closed at the dams, please visit www.tr.qld.gov.au/damstatus.