Scattering ashes

My last sister died suddenly earlier this year. She had asked me and also stated in her Will that her ashes be scattered on the cliffs of the small seaside town where we were all born and brought up. We all had some very happy memories of the place.
I have been told that you cannot do this as it is classed as Council property and also not on the sea shore as it would pollute the water.
The family is planning to go down late one evening next month and hoping no one will be around so we can quietly do this, and say goodbye to her.
Has anyone been in this situation and been able to do it quietly.