Youths are once again being warned to stay out of Horbury Lagoon after police patrols found life rings had been removed and thrown into the water.
Officers say the buoyancy aids have been used as water toys for youngsters who are playing in the former quarry.
A police spokesman said: “When will they learn? Total disregard shown by the youths towards other peoples safety.”
Several people have died in the lagoon, including a 32-year-old man who got into difficulties last year.