A sign representing a community was sometimes a more effective deterrent than a official council sign.
Whangaruru School children made their own sign after a massive illegal dump was found in steep bush on Ngaiotonga Rd.
The sign reflected the pupils' concerns about their environment, Mr Alsop said.
In 2016 the Far North District Council spent $14,000 cleaning up that site.
Clean-ups at several sites cost WDC $200,000 in the last financial year.
A car body was among items cleared from dense native bush down a bank on unsealed Kaiikanui Rd, near Mimiwhangata last month.
Fridges, dryers, ovens, a TV, a bicycle, beds, household rubbish, recyclable items and more were in that pile.