Issued by South Wales Police, the order covers Cosmeston Country Park and follows a day of serious safety concerns involving groups of young people.
It enables officers to direct individuals or groups to leave the area if their behaviour risks causing alarm or distress.
Rob Thomas, chief executive of Vale of Glamorgan Council, said: “We have been in discussion with South Wales Police about this situation, which has escalated throughout the day.
“Large numbers of teenagers have been jumping into the water and engaging in anti-social behaviour.
“Repeated requests to stop have been ignored, as have warnings about the risks of entering open water without lifeguards and safety precautions in place.
“Council staff have been met with abuse as they attempt to protect youngsters from serious injury.
“Cold water shock can kill as can strong currents and hidden hazards.”
The dispersal order will remain in place until the evening of Friday, June 26.
Vale of Glamorgan Council is urging parents to remind young people of the dangers and to encourage them to swim only in designated areas.
