Irresponsible youths are risking their lives by breaking into a Pendle construction site and causing a "nuisance" by playing near to a pond.
Police are warning the "disruptive" groups of youths to stay away from Seddon's new housing estate in Salterforth and the nearby deep cold water pond.
Officers are also urging parents to keep an eye on their children in the evenings and educating them about the dangers of playing on the site on Earby Road.
The move follows a recent incident where youths were spotted throwing life-saving equipment into the water.
A spokesman for Lancashire Police said: "Your local neighbourhood Police team are appealing to parents to warn their children about the dangers of being around the new pond on Seddon's new housing estate in Salterforth.
"This development contains deep cold water and the embankment is yet to stabilise and will be slippery when wet making it easy to fall in and difficult to get out.
"A neighbourhood watch in the area has identified this small group who after being disruptive around the estate then apparently threw a life-saving buoy into the water. The incident happened on Monday, March 25th, around 6 to 7-30pm.
"We are not seeking the identity of these children on this occasion, or pursuing any offences, however we would hope anyone identifying these people take it amongst themselves to prevent any further nuisance in the area by having the necessary conversation with them."
Barnoldswick councillor, David Whipp said: "I am aware of this issue and I have had contact with residents in the area.
"There are issues with young people behaving inappropriately all over the place - locally and beyond. The sad thing is that a lot of the positive initiatives such age groups could get involved into have been axed. We no longer have youth clubs that are open to all. I am not defending any anti-social behaviour, but there is a question mark as to how far services can be cut.
"Meanwhile, I agree with the police's message to parents to keep an eye on their children and always be aware of what they are up to."