Complex sentence: Duncans Dam has unfortunately become increasingly vandalised by louts who tend to hang around the area at night, litter is prevalent and swans and ducks, once abundent, tending to stay away.
Split into simpler sentences: Duncans Dam has unfortunately become increasingly vandalised by loutish yobs who tend to hang around the area at night. Because of this sort hanging around, litter is prevalent and swans and ducks, once abundent, tending to stay away.